Talk:History of life/Archive 1

July 2007
The page is currently under construction. it is requested to discuss before making any changes. Sushant gupta 09:24, 18 July 2007 (UTC)

Problem with article history
Hi there, there is a problem with the article as it stands. Much of the text appears to have been copied and pasted from other articles without linking the articles concerned in the edit summary. Please read Merging_and_moving_pages as a guide to do this in the future. Tim Vickers 17:17, 31 August 2007 (UTC)


 * I asked about how to deal with this at the help desk and they said we have to list the source articles here and in the edit history. I recognize the text I wrote in the Evolution article, where else was material copied from? Tim Vickers 19:29, 31 August 2007 (UTC)


 * the main articles mentioned above each section except some of them are the links i followed in order to write this article. I also took some of the content from the page Evolution. thanks, Sushant gupta 11:57, 1 September 2007 (UTC)


 * This doesn't need to be deleted, I just need to cite the articles used in the edit history of this article and on the talk page. Since this will be much easier for you to do than me, could you put a list here? Thanks Tim Vickers 13:45, 1 September 2007 (UTC)


 * That's great, I've added them to the edit history as well, so this article is now fully GFDL compliant. Tim Vickers 03:15, 2 September 2007 (UTC)

List of links followed in order to generate this article-
 * Early signs of life
 * Evolution
 * Precambrian
 * Paleozoic
 * Mesozoic
 * Cenozoic
 * Cambrian explosion
 * Ordovician-Silurian extinction events
 * Permian-Triassic extinction event
 * Late Devonian extinction
 * Triassic-Jurassic extinction event
 * Cretaceous–Tertiary extinction event
 * Holocene extinction event
 * Prokaryote
 * Eukaryote
 * Archaea
 * Symmetry (biology)
 * Evolution of sex

Images

 * ✅ Can Image:Dna-split.png be replaced by Image:DNA_replication_split.svg?

Early signs of life

 * ✅ Why are so many words in quotes? That doesn't seem necessary. Panspermia, error, food, and successful, in particular. Strains also seems odd unless they weren't actually strains but something similar.
 * ✅ Why is genetic code italicized?
 * ✅ "The first simple, sea dwelling organic structures appeared about 3,400 million years ago." - How do you know?
 * ✅"It is considered that they may have formed when certain chemical (organic) molecules joined together." - Considered by whom?
 * truely speaking i don't know who considered it but i have added ref to it. Sushant gupta 14:14, 9 October 2007 (UTC)

Evolution of life

 * ✅ "Amphibians first appeared around 300 million years ago, followed by early amniotes, then mammals around 200 million years ago and birds around 100 million years ago (both from "reptile"-like lineages)." - How do we know?

Life before Cambrian

 * ✅ "but carbon in 3800 million year old", "3460 million years" - Shouldn't those be 3.8 billion and 3.46 or 3.5 billion?
 * ✅ "Excepting a few contested reports of much older forms from Texas and India, the first complex multicelled life forms seem to have appeared roughly 600 Ma." - A reference about the contested reports would be good. The rest of this section could also use referencing.


 * Mesozoic life
 * ✅ This section is completely unreferenced.


 * Cenozoic life
 * ✅ Why is "age of new life" emboldened?


 * Late Devonian extinction
 * ✅ This section needs additional references.
 * ✅The (McGhee 1666) needs to be footnoted.


 * Triassic-Jurassic extinction event
 * ✅ This section lacks citation.


 * Holocene extinction event
 * ✅ Why is "Sixth Extinction" emboldened?
 * ✅ Additional citation needed in second half.


 * Prokaryote
 * ✅ Why is "protobionts" emboldened?
 * ✅ Needs citation.
 * ✅ Why more emboldened terms?


 * Eukaryote
 * ✅ "Knoll (1992)" - That needs to be footnoted and expanded.
 * This is still in the body. It shouldn't be. And there's nothing in the references to explain what Knoll (1992) refers to.

Evolution of asymmetry

 * ✅ Lacks citation.
 * Deleted. Tim Vickers 18:53, 7 October 2007 (UTC)

Section headers
✅ For the subsections that are emboldened with  rather than subsectioned with   or , is there any reason for this? I think it would be more appropriate to make headers so that the article is more easily editable with tabs for each of these sections. I have to leave off here for now. I'll return later.  Lara Love  19:27, 28 September 2007 (UTC)

GA on hold
Sorry for the break. As I completed the article, I added more issues above. I've noticed there are a lot of sections missing citation. One per paragraph is kind of what's preferred as a minimum, although there's no set number or anything like that. Without citation it reads like original reseach. Normally, I would fail an article for having this many citation issues, however, because the article was on hold for so long, I'm inclined to cut a break here. Hold periods are for seven days, do you think all of these issues can be corrected in that time?  Lara  ❤  Love  16:12, 4 October 2007 (UTC)

I'd also like to add that I just looked over the FAC discussion and while the article still needs some work, it is obvious that a lot of hard work has gone into it and that's something to be proud of. Keep up the good work!  Lara  ❤  Love  16:16, 4 October 2007 (UTC)


 * There's only a few small things left. I went through and did a little more tweaking. Very good article. Just fix the few ref issues and that's it. I'll list it. :) Regards,  Lara  ❤  Love  19:02, 8 October 2007 (UTC)

GA pass
This article has been listed at WP:GA. Thank you for all of your hard work. In improving this article, you have improved Wikipedia. Regards,  Lara  ❤  Love  14:29, 11 October 2007 (UTC)

Structure and questions
Hi, a couple of comments on this article. Firstly, the structure strikes me as very odd! Why not introduce the important concepts, then lay things out chronologically? It seems odd that the "three domain system" and "evolution of sex" are placed at the end of this "history". Wouldn't it make more sense to introduce them earlier? I'm not really sure where the "Three domain system" fits into the scope of this article, either. I'd consider either linking it in better, or removing it entirely.

Also, Funisia ought surely to be mentioned in the "Evolution of Sex" section. The opinion that selection pressures can act on levels above the individual (i.e. the "clade") does not, as I understand it, hold much popularity. It's probably worth providing an indication of this in the article (and some citations backing up the suggestion of "group selection").

There are a few other little things I'd have addressed before offering this article for GA status: for example, the inconsistent introduction of mya (why introduce it half way through the article, then not use it again? Better to use Ma, the first time "Million years ago" is used, or just write it out in full each time.) Maybe offer a date for all 6 extinction events? And, the Cambrian explosion was certainly NOT an extinction event! Worth mentioning, of course. But could you make it fit better into the article, rather than just copying the lede of the Cambrian explosion article?

Thanks

Verisimilus  T  17:33, 18 April 2008 (UTC)

I'll be more direct that Verisimilus - I'm puzzled about how this article got to be a GA. A few glaring errors (there may be more): trilobites were the first animals with hard exoskeletons; Edicaran period began 1000 MYA. There are also omissions or only superficial comments relating to: Dealing adequately with these points will make the article a lot longer. I suspect the only way to keep the length within reasonable bounds is to limit its scope to: The first step(s) would have to be sketching out the new structure in a fairly detaile dmanner, so that we can see that it all hangs together. Philcha (talk) 18:43, 8 July 2008 (UTC)
 * Abiogenesis. It omits or deals only very sketchily with:
 * RNA world hypothesis and supporting theories such as Cairns-Smith's suggestion that clays acted as the first replicators and thus provided "templates" for RNA-based replicators.
 * Possibility that lipid membranes "evolved" separately, and then somehow "combined" with RNA replicators to makle the first cells.
 * Date of the Last Universal Common Ancestor needs to be discussed. Geochemical evidence from rocks at Issua that life started almost as soon as the Hadean ended. Suggestions that the LUCA was an extremophile that descended from earlier froms and survived the final rounds of the Heavy Bombardment by living a long way below the surface.
 * Pre-Cambrian life.
 * The problem of the origins of triploblastic bilaterian animals.
 * The evolution of plants and fungi. This article is too animal-centric, and needs contributions from paleobotanists and paleomycologists.
 * The transition from water to land, for both animals and plants.
 * Deals ony with cellular life, omitting viruses, plasmids and other non-metabolising replicators.
 * Evidence for common descent.
 * When and in what conditions the first life arose. This will get into the question of the earth's atmosphere, and possibly why the early earth was not an ice-house (the sun's energy output increases by 10% per billion years, so it was about 40% lower when life arose).
 * Abiogenesis.
 * The three domains (prokaryotes, archea, eukaryotes)
 * Animal evolution up to the Cambrian.
 * Plant evolution up to the colonisation of land by plants (Devonian).
 * Evolution of land animals - tetrapods, insects, etc. This implies skipping from the Cambrian straight to the Devonian.
 * A note on mass extinctions.

General

 * (Peripatus) Major Events in the History of Life - survey w refs
 * - don't use his classification scheme, it isn't widely accepted, but good as a broad survey.

Earliest signs

 * J. William Schopf (April 1993) Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life Science: Vol. 260. no. 5108, pp. 640 - 646; DOI: 10.1126/science.260.5108.640 - 3465 MYA; thinks they're cyanobacteria
 * S. J. Mojzsis, G. Arrhenius, K. D. McKeegan, T. M. Harrison, A. P. Nutman & C. R. L. Friend (November 1996) Evidence for life on Earth before 3,800 million years ago; Nature 384, 55 - 59 (07 November 1996); doi:10.1038/384055a0 - Isua
 * Christopher M. Fedo, Martin J. Whitehouse Metasomatic Origin of Quartz-Pyroxene Rock, Akilia, Greenland, and Implications for Earth's Earliest Life; Science 24 May 2002: Vol. 296. no. 5572, pp. 1448 - 1452 DOI: 10.1126/science.1070336 - criticism re Isua
 * Mark A. van Zuilen, Aivo Lepland & Gustaf Arrhenius (2002) Reassessing the evidence for the earliest traces of life; Nature 418 627–630 - criticism / retraction(!) re Isua
 * Richard Corfield (2002) Fossil feuds Chemistry fuels debate on Earth's oldest inhabitants; Chemistry in Britain, 38 (9) pp 29-31 - reports the "traditional" evidence and questioning of it
 * Debating evidence for early life Geotimes (Nov 200) - debate over recent evidence.
 * Aivo Lepland, Mark A. van Zuilen, Gustaf Arrhenius, Martin J. Whitehouse and Christopher M. Fedo (January 2005) Questioning the evidence for Earth's earliest life—Akilia revisited; Geology; v. 33; no. 1; p. 77-79; DOI: 10.1130/G20890.1 - questions the most recent evidence
 * Grotzinger, J. P. & Rothman,D. H. 1996 An abiotic model for stomatolite morphogenesis. Nature 383, 423–425. (doi:10. 1038/383423a0)
 * van Zuilen, Mark A.; Lepland, Alvo; Arrhenius, Gustaf 2002: Reassessing the evidence for the earliest traces of life. Nature 418: 627-630.
 * Martin Brasier, Nicola McLoughlin, Owen Green, David Wacey (June 29, 2006) A fresh look at the fossil evidence for early Archaean cellular life; Phil. Trans. R. Soc. B Volume 361, Number 1470 pages=887-902 DOI=10.1098/rstb.2006.1835 - possible evidence at 3.4Gyr Strelley Pool Chert; I've found no sign yet that this is disputed.

Environment of first life

 * Karl O. Stetter, Hyperthermophiles in the History of Life in "Ciba Foundation Symposium 202 - Evolution of Hydrothermal Ecosystems on Earth (And Mars)?" (Editor: Gregoy R. Bock, Jamie A. Goode), Wiley, ~Sept 2007, Print ISBN: 9780471965091 - Growth demands of hyperthermophiles fit the scenario of a hot volcanism-dominated primitive Earth; need only active volcanism and liquid water
 * Sydney Leach, Ian W.M Smith, and Charles S Cockell (2006) Introduction: conditions for the emergence of life on the early Earth; Philos Trans R Soc Lond B Biol Sci. 2006 October 29; 361(1474): 1675–1679. doi: 10.1098/rstb.2006.1895 - intro/ index to a "survey"

Common descent

 * Orgel THE ORIGIN OF LIFE ON THE EARTH; Sci. Am 1994 (also as PDF - some common biochemistry.

Three domains

 * Joel Cracraft, Michael J. Donoghue (book, 2004) the Tree of Life another bacteria-archaea-eucaryote cladogram, animals & fungi closer to each other than to plants
 * Norman R. Pace (Jan 2008) The Molecular Tree of Life Changes How We See, Teach Microbial Diversity Microbe Magazine Volume 3, Number 1, - also web page summary - "procaryote" imprecise; 2 phylogenies of eucaryotes; bacteria-archaea-eucaryote cladogram

LUCA

 * Woese 1998 The universal ancestor; PNAS  June 9, 1998   vol. 95  no. 12  6854-6859 - LUCA not very sophisticated or efficient; it only had to  be better than its competitors.
 * Nicolas Glansdorff, Ying Xuand Bernard Labedan (2008) The Last Universal Common Ancestor: emergence, constitution and genetic legacy of an elusive forerunner; Biology Direct 2008, 3:29doi:10.1186/1745-6150-3-29 - LUCA a eucaryote w much genetic redundancy, eubacteria and archaea more specialised offshoots that evolved by "slimming down".

RNA World

 * Hugo Hoenigsberg Evolution without speciation but with selection: LUCA, the Last Universal Common Ancestor in Gilbert’s RNA world;Genet. Mol. Res. 2 (4): 366-375 (2003) (also PDF - direct competion between indiv RNA replicators/enzymes, w/o modern-stlye support form proteins, lipids etc.
 * Woese (2002) On the evolution of cells; PNAS  June 25, 2002  vol. 99  no. 13  8742-8747 doi: 10.1073/pnas.132266999 - frequent HGT until "a critical point is reached where a more integrated cellular organization emerges and vertically generated novelty can and does assume greater importance."

Microbial mats

 * - abstract with link to free full content (PDF) - oygenic photosyntheses; microbial mats as "nursery" of eucaryotes; lots more
 * other good citations at Microbial mat - but be careful w Krumbein et all, which is over-enthusiastic and makes some questionable claims.
 * John M. Olson, & Robert E. Blankenship (2004) Thinking about the evolution of photosynthesis; Photosynthesis Research 80: 373–386, 2004.

Diversification of eucaryotes

 * Sabrina D. Dyall, Mark T. Brown, Patricia J. Johnson (April 2004) Ancient Invasions: From Endosymbionts to Organelles; Science Vol. 304. no. 5668, pp. 253 - 257 DOI: 10.1126/science.1094884 - "endosymbionts lost the bulk of their genomes, necessitating the evolution of elaborate mechanisms for organelle biogenesis and metabolite exchange ... "
 * Fedonkin (2003) The origin of the Metazoa in the light of the Proterozoic fossil record Paleontological Research, vol. 7, no. 1, pp. 9-41, March 31, 2003 - impact of changes in air and ocean chemistry, some caused by geological processes and some by life itself; early metazoans; survey of mol phylo analyses; development of multicellularity possibly convergent, possibly very fast once started; cyanobacteria may have inhibited early animal evolution; late Proterozoic "Snowball Earth" episodes may have favoured eucaryotes
 * Joel Cracraft, Michael J. Donoghue (book, 2004) the Tree of Life another bacteria-archaea-eucaryote cladogram, animals & fungi closer to each other than to plants
 * S L Baldauf and J D Palmer (December 15, 1993) Animals and fungi are each other's closest relatives: congruent evidence from multiple proteins, PNAS vol. 90 no. 24  11558-11562
 * Palaeos Eukarya: Contents leads to lot of material and refs
 * Palaeos Eukarya: Contents leads to lot of material and refs

Evolution of atmosphere

 * get refs from Tetrapoda: Acanthostega] on enzyme rubisco.
 * The Plant Kingdom's sloth: Protein Spotlight article on the "slothful" enzyme Rubisco

Emergence of multicellularity

 * - simple explanation of many grades of multicellularity, w beautiful diagrams.
 * range of organisms in which multicellularity evolved independently
 * - starts with good def of "multicellular", which would still include Volvox; lot of other good stuff.
 * - impact of changes in air and ocean chemistry, some caused by geological processes and some by life itself; early metazoans; survey of mol phylo analyses; development of multicellularity possibly convergent, possibly very fast once started; cyanobacteria may have inhibited early animal evolution; late Proterozoic "Snowball Earth" episodes may have favoured eucaryotes

Sexual reproduction

 * Funisia?
 * Nicholas J. Butterfield (Sep 2000) Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes; Paleobiology; September 2000; v. 26; no. 3; p. 386-404; DOI: 10.1666/0094-8373(2000)026<0386:BPNGNS>2.0.CO;2 - sexual repro 1200 MYA

Animals

 * GONZALO GIRIBET, CASEY W. DUNN, GREGORY D. EDGECOMBE, GREG W. ROUSE A modern look at the Animal Tree of Life; Zootaxa 1668: 61–79 (2007)

Cambrian explosion

 * Andrew H. Knoll and Sean B. Carrol Early Animal Evolution: Emerging Views from Comparative Biology and Geology; Science 25 June 1999: Vol. 284. no. 5423, pp. 2129 - 2137 DOI: 10.1126/science.284.5423.2129 - overview (Ediacaran-Cambrian)
 * Retallack, G.; Freakes, C.R. 1987: Trace Fossil Evidence for Late Ordovician Animals on Land. Science 235: 61-63.

Plants

 * Paul Kenrick & Peter R. Crane, The origin and early evolution of plants on land; Nature vol 389 Sept 1997 - review of current research
 * Taylor TN, Osborn JM. 1996. The importance of fungi in shaping the paleoecosystem. Review of Paleobotany and Palynology 90: 249–262; DOI: 10.1016/0034-6667(95)00086-0
 * Daniel S. Heckman et al, Molecular Evidence for the Early Colonization of Land by Fungi and Plants, Science 10 August 2001, Vol. 293. no. 5532, pp. 1129 - 1133 DOI: 10.1126/science.1061457 - 700 MYA
 * - fungi colonised land in Cambrian
 * Kenrick, Paul; Crane, Peter R. 1997: The origin and early evolution of plants on land. Nature 389: 33-39.
 * get refs from Tetrapoda: Acanthostega] on Devonian wood crisis
 * get refs from Tetrapoda: Acanthostega] on Devonian wood crisis

Vertebrates

 * Fish Out of Water (Devonian Times) has useful-looking refs
 * Clack, J. A. 1989."Discovery of the Earliest-Known Tetrapod Stapes," Nature, 342:424-427.
 * Clack, J. A. 2002. "An Early Tetrapod from 'Romer's Gap'. Nature, 418:72-76
 * Coates M. I. and J. A. Clack, 1990.. "Polydactyly in the earliest Known Tetrapod Limbs," Nature, 347: 66-67
 * Coates and Clack, "Fish-like Gills and breathing in the earliest known Tetrapod," Nature, 352, July 18, 1991, p. 234-236
 * Coates,M.I., 1994. "The Origin of Vertebrate Limbs," Development 1994 Supplement, 169-180, p. 174
 * Ahlberg,P. E. 1991, "Tetrapod or Near-tetrapod fossils from the Upper Devonian of Scotland," Nature, 354:298-301.
 * Ahlberg, P.E. and Andrew R.Milner, 1994"The Origin and Early Diversification of Tetrapods," Nature April 7, 1994.

Hominid evolution
-- Philcha (talk) 13:18, 6 September 2008 (UTC)
 * Michael J. Benton and Philip C. J. Donoghue (January 2007 ) Paleontological Evidence to Date the Tree of Life; Molecular Biology and Evolution 2007 24(1):26-53; doi:10.1093/molbev/msl150 - dates for early hominines; may be able to build cladograms from it; and for other important divergences

Outline for possible rewrite
Biologists generally avoid the question. Schrödinger's definition as local violation of entropy. Body and trace fossils. Geochemical. Molecular. Panspermia. Abiogenesis. RNA world & "clay world". "Metabolism first". "Membranes first". Darwin's "Warm little pond". Hydrothermal vents. Gold's "hot, deep bioshpere". Earliest atmosphere. Fatal levels of cyanide. Reduction in geological inputs. Shift away from "bicarbonate" oceans. Oxygenic photosynthesis. Main divisions of eucaryotes. Symbiotic theory of origin, possibly "catalysed" by microbial mats. Procaryotes may have inhibited spread and diversification of eucaryotes. Protists, algae Undifferentiated: Porifera. Tissue-grade: Cnidaria (diploblasts). Bilaterian / triploblastic: acoelomate, pseudocoelomate, protostome, deuterostome. -- Philcha (talk) 08:37, 26 August 2008 (UTC)
 * Definition of life
 * Types of evidence
 * Common descent:
 * Darwin suggested it. Proof from molecular biology - too may shared mechanisms: amino acids & proteins, DNA for "recording", RNA for "reading" DNA and making proteins, ATP, etc.
 * Three domains:Short description. No consensus on their phylogenetic relationship - LUCA problem. Horizontal gene transfer - and was it necessary?
 * LUCA (Woese 1998 The universal ancestor)
 * Origin of life on Earth - note "cross-fertilization" (half-witty!) w exobiology / astrobiology
 * Fossil evidence. Right at end of Late Heavy Bombardment. Geochemical evidence at Issua. Fossils in Astralia & S. Africa.
 * Possible processes
 * Environment
 * Before eucaryotes became significant.
 * Changing environment
 * Earliest ecosystemsAll "procaryote" (? explain briefly why term out of fashion). Microbial mats most productive, and nurseries of evolution. Mats still the dominant life on Earth?
 * Rise of eucaryotes:
 * Early single-celled eucaryotes
 * Early animals:
 * Major types
 * Early history Body and trace fossils. Indirect evidence, e.g. decline of stromatolites. Ediacarans. Cambrian explosion.
 * Early plants
 * Early fungi
 * Colonization of land.


 * Such a re-write is long overdue. The only things I'd add to your list would be life elsewhere (worth looking at 10.1017/S1473550408004175 for a nice overview of "Life on Mars"), and Early algae, which you perhaps tag into "plants". And I wonder whether Evolution of fungi might benefit from a bit of attention in the crossfire? Martin  (Smith609 – Talk)  11:57, 27 August 2008 (UTC)


 * Re algae, I've added "Early single-celled eucaryotes".
 * Thanks for the refs re Life on Mars, but I suspect this article will become pretty large w/o getting into exobiology / astrobiology / whatever - Drake equation, Fermi paradox, Lonely Earth hypothesis, exotic biochemistries, stellar habitable zone, galactic habitable zone, etc. Yes, my other life-long addiction is science fiction!
 * Re Evolution of fungi, I only have enough info for a brief section in Evolutionary history of life - and my impression is that there may not be a whole lot more. Besides, there's plenty to do at WP:CEX and I have a pipeline of chess articles to polish up for GA. -- Philcha (talk) 12:10, 27 August 2008 (UTC)


 * On second thoughts, it would be good to note, and no more than that, "cross-fertilization" (half-witty, before anyone says it!) w exobiology / astrobiology. -- Philcha (talk) 12:48, 27 August 2008 (UTC)


 * Watch out for the "large, fierce bias" - animals may be quite interesting to look at but prokaryotes have always dominated life on earth. If you can get hold of a copy of Gould's Full House: The Spread of Excellence from Plato to Darwin. Tim Vickers (talk) 23:15, 3 September 2008 (UTC)


 * Tim, the bigger danger was that I might include too much from Microbial mat, which I wrote. Woese's arguments for a simpler LUCA imply that the big moments in bacterial and archaeal evolution were well back in the Proterozioc, and and a Schopf article I haven't used commnets what he considers a genuine increase in the pace of evolution. OTOH a quick survey of the modern ecosphere might be good, just before the closing "Evolution continues" which I mentioned in my message to you. Do you have anything on e.g. the relative contributions of cyanobacteria and rainforests to total oxygenic photosynthesis?
 * BTW I've read Gould's "batting average" essay and the one about "the complexity distribution is bounded at one side". The Crucible of Creation and The Major Transitions in Evolution might have something to say on the other side.
 * I'm beginning to think the last few sections should be:
 * increase in the pace of evolution (or trends generally, per The Major Transitions in Evolution).
 * survey of the modern ecosphere
 * evolution continues-- Philcha (talk) 00:14, 4 September 2008 (UTC)


 * That is covered in this article, which suggests total primary production is split evenly between land and ocean. I think most of the oceanic production is due to algae. Tim Vickers (talk) 18:34, 13 September 2008 (UTC)


 * Thanks, Tim! -- Philcha (talk) 20:24, 13 September 2008 (UTC)

Work in progress
I think the current content about LUCA is fairly good, but it's far too long and the article should address other theories - those focussed on metabolism, those focussed on cell membranes and even panspermia.

I will transfer the current LUCA material to other articles when I'm happy with the summary of "Origins of life on Earth", summarising a wide range of hypotheses. Do not delete, move or shrink it. OTOH i fyou have good material to add, please do so. --


 * My intention wasn't to expand the "evidence of earliest life" section but to improve the reading style a little - It felt like I'd trimmed it, if anything. Although I do think a very brief note of whether the earliest evidence is a fossil or geochemistry would be helpful.
 * In other news I'm not sure that panspermia is dealt with appropriately at the moment. The impression I get is that if life began on another planet, that's a suitable explanation for how life began.  The section that was called "Origin on Earth" could apply just as well to any other rocky body.  Perhaps a rethink would be helpful? Martin  (Smith609 – Talk)  19:08, 1 September 2008 (UTC)


 * Re "Evidence", you removed an item about a report (2006, IIRC) of geochem evidence for . Has that been refuted?


 * I think panspermia's for wimps, but could't find a ref for that. More seriously, panspermia: only moves the problem; does not make sense if the source is elsewhere in our solar system, as Earth has always been overwhelmingly the most life-friendly planet; does not make sense from outside the solar system unless you beleive it was a deliberate act by very advanced aliens, because sub-light interstellar trips take 10s of thousands of years - but no refs for that either. The problem is that, apart from what I cited, it seems only fringe journals (by WP standards) and over-eager / imperialistic astronomers mention it, and they seem keen on the idea. That'w why I cited the "25 years on" Crick & Orgel paper.


 * "Origin on Earth" could apply just as well to any other rocky body - no, to any very Earth-like rocky body (by biologists' standards, not astronomers'!), and the only known one and by far the nearest is ... Earth. -- Philcha (talk) 19:43, 1 September 2008 (UTC)


 * Got some refs re panspermia >-) -- Philcha (talk) 09:31, 2 September 2008 (UTC)

---

i have re-structured the article. now the article has a good flow. i have clubbed the diversification of eucaryotes section with three domain system. hope so now it looks good. Sushant gupta (talk) 12:02, 3 September 2008 (UTC)

Some problems
This article has been much improved but I think there are now some undue weight issues most of which involve giving new "cutting edge" hypothesis more attention than older but still more widely accepted ideas. Here are some examples:


 * The section on the evolution of sex doesn't even mention the Red Queen hypothesis, which says sex evolved primarily as a way to combat rapidly evolving parasites by maintaining genetic divirsity. This despite the fact that (as the evolution of sexual reproduction article points out this is still the most widely held theory.
 * The section on the evolution of social insects spends more space on recent criticisms of the kin selection theory of eusociality than it does on explaining that theory even though that theory is still far more accepted than the proposed alternatives. The eusociality article has a fairer balance, although in my opinion it is a little unbalanced in favor of the newer ideas as well.

This sort of bias can creep into a scientific (especially an article on a large topic such as this one) from a couple of sources. One is over reliance on recent technical literature (scientific papers) that focus on new ideas (or challanges to existing established ideas) at the expense of using more general sources (such as text books) that provide a more balanced evaluation of different ideas. Another source of this kind of bias is editors who are reasonably knowledgeable in an area and are excited by new ideas (or challanges to old ideas) and who forget that the typical reader of an encyclopedia article won't be as familiar with the established ideas as the editor is. I think a "big topic" article like this should primarily emphasise the most established ideas and leave it to more specific articles to which it links to explain newer developments/challanges to the established ideas. I think not respecting this principle has contributed to another problem this article has, which is that it is probagbly 20-25% too long now. I am willing to help with edits to address these problems, but I thought it was worth discussing on the talk page first. Rusty Cashman (talk) 20:06, 9 September 2008 (UTC)


 * Thanks for the comments. The article's not complete yet. I'm glad you think it's going in the right direction (mainly).When I've done the first draft I'll leave for a week and then try to read it with fresh eyes. Keep on commenting!
 * Re specifics:
 * I'm not happy with the bit about the origins of sex, which I more or less imported from the "main" article". I'll look for more material. OTOH I think the Red Queen hypothesis (I've got Ridley's book) works better for multi-celled organisms, but Butterfield's argument is that sexual reproduction is a prerequisite for multicellularity, i.e. he implies it evolved in unicellular organisms. I can't see cellular parasites making a good living form unicellular organisms, but parasitic replicators are another matter – but the bit on origins of sex covers that (sort of).
 * I'll also see if I can find more on eusociality. But E.O. Wilson is huge in the study of social insects. -- Philcha (talk) 20:30, 9 September 2008 (UTC)


 * I've realised I omitted the fact that termites are diploid and have workers of both sexes. In the 1980s someone proposed that a complicated re-shuffle found in the termite genome could create the same effect as haplodiploidy - see The Evolution of Eusociality in Termites: A Haplodiploid Analogy? and A Haplodiploid Analogy in the Evolution of Termite Eusociality? Reply to Lacy. However if the re-shuffle is responsible for termite eusociality, the sex-linked nature of the re-shuffle would imply that workers should give preferential treatment to infants of their own sex, and this is not corroborated by observations - see A test of the haplodiploid analogy hypothesis in the termite Reticulitermes speratus. In addition eusocialy is not an on-off condition, there are degrees. For example in some bumble bees there are are tensions between the queen and her "princess" daughters, and the "princesses" generally kill the queen in late summer. AFAIK all wasps are haplodiploid, but: the majority of species are solitary; power-struggles are common in wasp nests.
 * However I'm no insectologist, and would welcome further input. -- Philcha (talk) 08:43, 11 September 2008 (UTC)


 * You're doing a really great job on this article, Philcha – I couldn't believe how much it had come on since I last looked! On a stylistic note, the "scientists believe" phrasing in the age of the earth stuff is a bit of an oddball; either it should be used throughout or (my preference) removed.  Content-wise, I think the current length and balance between topics is very good, but there are a couple of things that could be addressed; firstly the colonisation of land focusses on animals in much more depth than plants.  My suggestion would be to trim the vertebrates rather than expand the plants, but I think that one or other should be done.  It would also be nice to mention in passing why things took place when they did, especially the evolution of large size – a quick nod to increasing oxygen levels seems essential in an article of this nature. Martin  (Smith609 – Talk)  00:45, 11 September 2008 (UTC)


 * Thanks for the encouragement. Specifically:
 * In general I agree about "scientists believe". But I wrote ""scientists believe" twice in "Earliest history of Earth" for specific reasons: the evidence for 4.6 BYA is extremely circumstantial; the idea that Earth's surface stayed molten for 800 MY is obsolete but memorialised in "Hadean era".
 * I'd like more on colonisation of land by bacteria, plants & fungi. I asked a WP mycologist to see if he he could get a paleabotanist and or paleomycologist to have a look, but so far no respnse. I'll try the Wikiprojects. I can reduce the details of Acanthostega by 1-2 sentences, but the turn-round it caused on the forces behind the evolution of land vertebrates is important. There will still be old text books, especially in public libraries, that present the old view. Likewise I think the bit about the vegetated streams is important to illustrate the impact of ecological factors in evolution, which the old article omitted.
 * Keep on commentin' -- Philcha (talk) 08:15, 11 September 2008 (UTC)
 * Re. palaeobotany: I guess you've seen Evolutionary_history_of_plants? Martin  (Smith609 – Talk)  00:06, 14 September 2008 (UTC)
 * Rusty Cashman's comments on eusociality and the evolution of sex are quite valid. There is indeed a tendency for many un-overhauled articles to tend towards accumulating recent material with a lack of historical perspective. Regarding "scientists believe", the preference should be for something like "evidence suggests" which is more objective, cautious and less divisive. I came here from arthropod talk so - the land (invertebrate) arthropod section should include material on the declining connection between water and the organism, the hardening of the shell, appendages, flight, herbivory and the competition/coevolution with angiosperms. Shyamal (talk) 12:24, 11 September 2008 (UTC)


 * Hi, Shyamal, thanks for the input. Looks like the arthropod bits are going to generate some discussion. The general problem of an article with such huge scope is the need to be brief. Re the details:
 * The haplodiploidy / kin selection hypothesis about eusociality has some problems: termites are diploid and have workers of both sexes; there are degrees of eusociality, which haplodiploidy does not explain, and in fact most wasp species are solitary although haplodiploid. See The Evolution of Eusociality in Termites: A Haplodiploid Analogy?, A Haplodiploid Analogy in the Evolution of Termite Eusociality? Reply to Lacy and A test of the haplodiploid analogy hypothesis in the termite Reticulitermes speratus. If there are good explanations for these difficulties which can be summarised in a sentence, please let me know.
 * As I said, I deliberately wrote "scientists believe" twice in the same section for specific reasons. Otherwise I usually avoid it it (I think).
 * Re the "land invertebrate" section, factors wich affect all organisms including plants are in the containing section while those that are animal- / plant-specific are in the sub-sections. I hoped I'd covered them adequately.
 * Re hardening of the shell and appendages, that actually happened in the Cambrian seas - trilobites, crustacea, chelicerates. So arthros were pre-adapted for life on land. But I have to draw the line somewhere in an overview article. If you can supply a short sentence w ref about arthros' pre-adaptation for life on land, I'd be happy because that would highlight another evolutionary principle, something I've tried to weave into the mainly chronological account.
 * I also thought I'd covered coevolution of insects & angiosperms.
 * Look forward to hearing from you. -- Philcha (talk) 13:35, 11 September 2008 (UTC)

Lead
I'm happy enough that the lead summarises the main text well. WP:LEAD says 4 paragraphs max, but I don't think that fits the range of time, subjects and scientific disciplines that this article covers. I think that combining the topics into fewer paras would confuse newbie readers. And the last para is meant to be arresting.

Comments / suggestions, please. -- Philcha (talk) 18:20, 13 September 2008 (UTC)


 * Tricky one. Difficult to keep it short without reducing it to a list of dates.  One comment; some paragraphs of the lede are barely shorter than the equivalent text in the article, whereas some article sections are summed on in a mere sentence. Also, some "facts" in the lede are only weakly supported in the text.  Martin  21:33, 13 September 2008 (UTC)


 * You don't need to tell me it's tricky! The need for brevity is the problem, in both text and lead. Sometimes I've got the main text as brief as I can manage without obscurity (I fondly hope). Can you please identify specific problem areas.
 * Any thoughts on number of paras in lead.? -- Philcha (talk) 21:43, 13 September 2008 (UTC)


 * Well, I'd disapprove of paragraph counting simply to fulfil WP:LEAD. The guideline is meant, I think, to give an indication of a sensible length for the lead; in my opinion, it's currently about twice as long as it should be.  I think the difficulty arises because the lead is trying to sum up a summary article.  There are a lot of one-line facts, all of which are equally significant.  What I'm going to do is to try a different approach, focussing on the concepts rather than trying to match the article structure paragraph for section.  Give me 30 minutes and see what you think! Martin  (Smith609 – Talk)  23:05, 13 September 2008 (UTC)


 * Grr. Chrome lost all my work (so much for that browser...), so my frustrated re-write is not as finely constructed as the first version. But I think it tells a more coherent story and is now a good length.  How does it grab you? Martin  (Smith609 – Talk)  23:53, 13 September 2008 (UTC)


 * You're not having much luck with browsers lately, are you? I remember you cussing FF recently.
 * It's easy for me to give you 30 mins, as we're now in time zones over 5 hours apart.
 * I hate to be an ungrateful git, but I much preferred the previous lead, spare tyre and all:
 * " appears that life evolved on Earth practically as soon as the planet had cooled enough for liquid water to be present" is dubious, sinc ethe may have een oceans.
 * I notice netiher yours nor mine mentions common descent!
 * "Whether the first organisms originated on Earth or hitch-hiked in on a meteorite, there are a number of plausible hypotheses for how inert molecules first became self-replicating and gained the other characteristics of living organisms" has a few holes:
 * "hitch-hiked in on a meteorite" is not the only version of panspermia.
 * Looks like "whether A or B, there are a number of plausible hypotheses for how A"
 * No mention of age of evidence for life
 * Decomposition not mentioned in text as food source for bottom layers of mats.
 * No mention of eucaryotes.
 * "Sexual reproduction allows for more rapid evolution" sounds like a theory of the origin of sexual reproduction per se, and one that is not mentioned in the text. The ext follows Butterfield's argument that sexual reproduction, however it arose, is a prereq for differentiated multicellular organisms.
 * "forests of land plants changed Earth's environment sufficiently to trigger one of the five largest extinction events" is not an accutate summary of what the text says about the Late Dev Wood Crisis.
 * "Following this catastrophe (presumably P-Tr), vertebrates such as the dinosaurs rose to become the dominant large land animals" makes it sound almost as if dinos were the first vertebrates.
 * No suggestion in text that social insects' evolution directly linked to flowering plants - and false, in case of termites.
 * "The extinction of the dinosaurs 65.5 million years ago, and a subsequent warm spell, allowed mammals to radiate" ?? "subsequent warm spell" not in text. If it's the PETM, it's linked to a minor mass extinction.
 * "The brains of one lineage of upright primates began to increase in size after about 3 million years ago" is AFAIK true, but not what the text says. The source covers brain sizes from an dsays nothing abut earlier.
 * "... gain sufficient intelligence to use tools and inflict new evolutionary pressures on the biosphere. Consequently, evolution is today running at its fastest ever rate as organisms struggle to adapt to a rapidly changing environment before they are rendered extinct" looks too enviro-preachy and does not reflect the text. " evolution is today running at its fastest ever rate"??
 * I suggest we both create sandbox versions, work on them for a few days,and then compare. -- Philcha (talk) 03:31, 14 September 2008 (UTC)


 * As a brief response, I feel that it's best to avoid both unfamiliar terms and controversial statements in the lead, as both need backing up with space-filling explanations. And things that I've mentioned in the lead that aren't in the text should perhaps be in the text, although I'm aware of the problem with article-bloat. I'll try to find time later to respond in more depth where necessary... Martin  (Smith609 – Talk)  03:59, 14 September 2008 (UTC)

Points flagged up
For about 2,000 million years microbial mats, multi-layered colonies of different types of bacteria, were the dominant life on Earth. Are there good sources for early plankton? A priori I'd suspect not, as atmosphere oxygenated around - there's a nice juicy target for you!

oxygen was stable from about - ????? was it radioactive or explosive before?

a development that may have started with their capturing oxygen-powered bacteria as endosymbionts. I hoped "capturing" would help. Is "internal symbionts" any better? If not can you thnik of a brief explanation that fits?

The earliest evidence of complex eucaryotes with organelles (" organs" within a cell) dates from. Well go on, suggest one that fits. Conclusion of GA reviews of Kimberella and Opabinia was that jargon gets w-linked but not explained in lead - perhaps just cut the explanation.

Budd (2008) (The earliest fossil record of the animals and its significance - I think the key passage is: "Despite the obvious uncertainties, the most reasonable interpretation of the data thus is that embryoforming animals of some sort had evolved by just after Marinoan time, and that sponges and presumed other animals had started to emerge by 580 Myr ago at the latest, and that the Ediacaran biotas are likely to be a little younger than the Doushantuo embryos...with an inferred documented fossil origin of the entire clade being datable to just after 635 Myr ago." He clearly agrees animals were around by, but picks sponges rather cnidarians. I dont' understand "inferred documented fossil origin" - to my simple mind they're either fossils or inferred. My text went with Chen, Oliveret lots of al (2002) Is there any other recent good stuff on earliest animals? NB the lead omits the debate over Horodyskia - wisely,IMO. I should have written "earliest widely-accepted evidence", but now you've made that difficult.

The lineage that produced land animals evolved later Should have said "produced land vertebrates".

the Permian–Triassic extinction event came very close to wiping out complex life. Inferred species extinction rates, Benton's "Day Life Nearly Died". Admittedly inferred rates for taxa below family are questionable.

Fossil evidence indicates that flowering plants appeared and rapidly diversified in the Early Cretaceous, between  and  I chose this phrasing because the apparently sudden appearance and dominance of angiosperms remains an "abominable mystery" (Darwin; Crepet 2000).

There is a long-running debate about whether modern humans evolved all over the world from existing advanced hominines I think you've over-reached yourself. AFAIK "paraphyletic" refers to a set of species, and fertility of mixed-race humans indicates we are 1 species.

-- Philcha (talk) 04:31, 14 September 2008 (UTC)

Edit undone
The folowing edit was undone:
 * Reasonably complete vertebrate fossils are very rare, most extinct vertebrates are represented only by partial fossils (thought this sometimes happens to invertebrates as well), and complete fossils are rarest in the oldest rocks. So paleontologists have mistakenly assigned parts of the same organism to different genera which were often defined solely to accommodate these finds – the story of Anomalocaris is an example of this. The risk of this mistake is higher for older fossils because these are often unlike parts of any living organism. Many of the "superfluous" genera are represented by fragments which are not found again and the "superfluous" genera appear to become extinct very quickly.

The point is that most fossils are invertebrates, mainly molluscs. -- Philcha (talk) 06:11, 28 September 2008 (UTC)

Article name
Technically, the period of history begins with the invention of writing 5000 years ago. History typically refers to recorded information. How, then can this article be entitled "evolutionary history of life"Shambalala (talk) 06:04, 16 October 2008 (UTC)


 * Words don't have fixed meanings. The original Greek word simply meant "inquiry" or investigaton", and that is preserved in the English phrase "natural history" referring to the study of living organisms, mainly in their own environment. Phrases like "history of Earth" or "history of the universe" are common. The problem may be that most people are familiar with the term "history" only from what they were taught at school, which is mostly restricted to humans since the invention of writing. Even in that limited context it's ambiguous, since it means both "what happened to humans since the invention of writing" and "the study of what happened to humans since the invention of writing." In general "history" means "what happened in the past" or "the study of what happened in the past."
 * "Evolutionary history of earth" does refer to recorded information - it's recorded in rocks and in genes, although scientists only learned how to read genes in the 1990s. -- Philcha (talk) 07:18, 16 October 2008 (UTC)


 * Quoting "history" from the OED:


 * A relation of incidents (in early use, either true or imaginary; later only of those professedly true); a narrative, tale, story. Obs. (exc. as applied to a story or tale so long and full of detail, as to resemble a history in sense 2.)
 * A written narrative constituting a continuous methodical record, in order of time, of important or public events, esp. those connected with a particular country, people, individual, etc.
 * That branch of knowledge which deals with past events, as recorded in writings or otherwise ascertained; the formal record of the past
 * A series of events (of which the story is or may be told)
 * Martin  (Smith609 – Talk)  12:45, 16 October 2008 (UTC)
 * Isn't there some redundancy in the name, the article could simply be titled "history of life" or "evolution of life". Shambalala (talk) 01:57, 17 October 2008 (UTC)
 * "Evolution of life" implies the origin of life; history of life doesn't place a focus on evolution. And those pages probably redirect here anyway so is it worth worrying about? Martin  (Smith609 – Talk)  04:29, 17 October 2008 (UTC)

Panspermia?
Is this really worthy of mention in the first paragraph, especially since it only a very small section of the overall article? Not to say that it shouldn't be included, but wouldnt it be better to say "The dominant theory is..., though several alternative theories have been proposed." Robogymnast (talk) 20:23, 21 October 2008 (UTC)


 * The problem is that I haven't worked out a good lead section yet, as my drafts are rather long. I'd apprecaite it if you could have a look at these and comment here. -- Philcha (talk) 21:18, 21 October 2008 (UTC)


 * It's possibly premature to list the article for GA before writing a good lead for it. I'll try to rehash my version of it later today. Martin  (Smith609 – Talk)  16:53, 8 November 2008 (UTC)

Mesozoic too small in graphical timeline
On the graphical timeline the box for the Mesozoic is too small and that for the Cenozoic is too big and you can't read the Mesozoic label. I don't understand how this thing is constructed so I can't fix it myself. Mikenorton (talk) 09:58, 16 November 2008 (UTC)


 * The real problem is that no single timeline can comfortably accommodate both the whole 4.6 billion years and the mere 543 MY since the start of the Cambrian. One of the article's objectives is to make it clear how little of the history of life well-known critters like dinosaurs and trilobites account for, and how many of the important steps happened before the Cambrian. Another timeline, e.g. Ediacaran-present, might be nice, but there isn't room as it would displace other illustrations which give important information about other topics. The actual proportions are calculated from the internationally agreed dates given to the template that draws the timeline, and are as right as they can be at the compressed scale: Paleozoic ~= Mesozoic + Cenozoic; Cenozoic is a little over 1/3 of Mesozoic. --Philcha (talk) 10:50, 16 November 2008 (UTC)


 * Philcha, the sizes as I see them (using Internet Explorer) are more like Paleozoic ~= Cenozoic = ca. 450 Ma, Mesozoic = ca. 100 Ma. The Mesozoic is so thin that the text doesn't appear. I presume that this is an issue with the template and the browser. I'm not expecting the thicknesses to be precise, but roughly proportional would be nice, if it's possible. Mikenorton (talk) 15:11, 16 November 2008 (UTC)


 * I just checked in IE 7 under Win XP SP 2 (reluctantly, as IE is a bug-ridden security hazard), and it looks identical to the px. No problems in IE or Firefox (get it now!) when I tried increasing the text size by silly %s. What IE and Win are you using? --Philcha (talk) 16:46, 16 November 2008 (UTC)
 * My IE version is 6.028 working with NT 2000 OS (OK I know that I'm long in need of an upgrade), so maybe it really is just me that has the problem. Thanks for looking at it anyway Philcha. Mikenorton (talk) 16:53, 16 November 2008 (UTC)

lead
The statement "However even the simplest modern organisms are too complex to have emerged directly from non-living materials." is somewhat misleading maybe even contradictory. The statement seems to be supportive of panspermia. I don't think there should be any opinions in the lead. My understanding is that people who believe in abiogenesis, think that complex life did emerge from non-living materials. Wapondaponda (talk) 19:52, 9 January 2009 (UTC)


 * AFAIK it's generally agreed that the simplest modern organisms are too complex to have emerged directly from non-living materials - see section "Origins of life on Earth" and the citation there, and also the first para of "Replication first: RNA world". Panspermia is not taken seriously by most biologists and paleontologists, and the search is on for simpler initial stages of life, as described in the sub-sections of "Origins of life on Earth". If you think the current wording of the lead is unclear, please propose an alternative, but remember that it has to be brief (like everything in this huge article). --Philcha (talk) 21:37, 9 January 2009 (UTC)
 * The section that you mention,origins of life on earth has a clearer explanation:
 * "However the earliest organisms for which fossil evidence is available are bacteria, which are far too complex to have arisen directly from non-living materials".
 * A side note to this is that viruses are simpler than all bacteria, since they lack a cellular structures. They can also exist in non-living crystalline form as was the case with the tobacco mosaic virus. Thus the debate on whether viruses are alive or not. I propose editing the lead to include something like the above sentence. Wapondaponda (talk) 23:03, 9 January 2009 (UTC)


 * To clarify, the key word here is "directly". People who believe in abiogenesis think that complex life emerged from non-living materials via a series of simpler stages, but not directly.  Back in the 1700s, many people thought that if you put the right nutrients into a jar and shook it up, you would automatically get life in a day or so.  No serious scientist believes that any more. Looie496 (talk) 22:31, 9 January 2009 (UTC)
 * Agreed on that. I do think that modern organisms aren't so relevant to the origins of life, since they are "modern". I think that the section that specifies fossil evidence is more relevant and less ambiguous in its connotations. In fact what you have mentioned about the simpler stages, is what is needed rather than the current sentence which seemingly, though maybe not intentionally, implies panspermia. Wapondaponda (talk) 23:14, 9 January 2009 (UTC)


 * The problem is that the lead is supposed to be briefer than the main content - which is already pretty brief,a s the artcile spans 4.6 billion years! At present "the simplest modern organisms are too complex to have emerged directly from non-living materials" looks OK to me provided the reader picks up modern and directly --Philcha (talk) 23:42, 9 January 2009 (UTC)
 * No problems with brevity. The sentence maybe OK to someone who frequently reads this article. But when I read it for the first time, I was confused. The previous sentence states:"All present-day organisms use the same large set of complex chemical reactions, which indicates that all modern organisms share a common ancestor". The next sentence starts with "however" which should relate to the previous sentence, but "however" introduces the new idea of the origins of life:"However even the simplest modern organisms are too complex to have emerged directly from non-living materials." This flows right into the next sentence about life being seeded from outer space. There are some grammatical issues that need to be resolved to make the meaning of the paragraph less ambiguous.Wapondaponda (talk) 01:19, 10 January 2009 (UTC)

Suggestion for GA
I'm considering undertaking a Good Article review for this article, but skimming through I notice one (I think) serious set of problems, related to the present-day situation that would need to be addressed before it's GA material. The end of the mass extinction section mentions the expansion of diversity in the wake of mass extinctions, with the last extending "from 200 million years ago to the present". In paleontology terms, where 10,000 years ago is pretty much the present, that may be true, but it's widely acknowledged that the rise of human civilization has caused widespread loss of biodiversity, most notably the extinction of many large land animals, and that industrialization has greatly accelerated the extinction rate (the figure that gets thrown around is that half of all species could go extinct by 2100). I would expect more coverage of the ongoing mass extinction.

Similarly, the discussion of the evolutionary trends that are underway today is underdeveloped; I would expect discussion of the systemic trends of many species evolving to deal with the impact of humans on the environment, as well as the coevolution (especially via artificial selection, and to a lesser extent genetic engineering) of many species upon which humans are directly dependent.--ragesoss (talk) 03:54, 7 December 2008 (UTC)


 * In terms of GA criteria, I don't think this article meets the requirements for 'completeness'; it doesn't really mention the Great Ordovician Biodiversification Event (GOBE) or the Mesozoic Marine Revolution. The importance of these is second only to the Cambrian Explosion itself and they deserve more coverage both here and on their own articles. Martin  (Smith609 – Talk)  20:08, 12 December 2008 (UTC)


 * Evolutionary history of life is already 59.7 KB of prose (excluding images, refs, etc.) - see this analysis script. So I think it has to focus mainly on how the organisms that readers are familiar with came to be here, giving more space to the parts of the process with which non-specialist readers are less familiar, e.g. abiogenesis, oxygenation of the atmosphere, and the rise of multicellular life with specialised tissues.
 * Correct me if I'm wrong, but AFAIK the Great Ordovician Biodiversification Event and the Mesozoic Marine Revolution didn't introduce any new types of organism (except possibly bryozoa), although they may have changed ecosytems significantly. I think it would be better to produce decent articles on Great Ordovician Biodiversification Event and the Mesozoic Marine Revolution and then see if they are significant enough to warrant reducing the coverage of other topics in Evolutionary history of life.
 * Likewise mass extinctions in general are only a part of the process, and even the P-Tr extinction (the "mother of all extinctions") and the K-T extinction, which opened the way for the evolution of modern mammals including humans, only get mentioned in a sentence each, within the same section. There's already a good package of articles about mass extinctions.--Philcha (talk) 00:30, 13 December 2008 (UTC)

I have noted at WP:GAC that I'll do a review of this article. It's an important topic and has languished for too long. I should have a thorough review to you within a week (at most). Thank you, Steven Walling (talk) 02:10, 14 December 2008 (UTC)


 * Might be redundant but I'll note a few things that I spotted in reading through:


 * 1) The "Evolution of sex" section is weak and perhaps isn't needed in this article.
 * 2) I think there ought to be a mention of snowball earth before the Ediacaran section, since it gives the best explanation of why the proliferation occurred at that time.
 * 3) The line "Anapsids; whether turtles belong here is debated" in the bird figure isn't quite right. There is no question that turtles are anapsids, the question is whether the anapsid line is slotted into the tree in the right place.
 * On the whole, this is quite a good job on a very extensive topic. Looie496 (talk) 05:12, 22 December 2008 (UTC)


 * Hi, Looie496, thanks for the comments
 * I think "Evolution of sex" is needed because: it's near-universal in eucaryotes (see citation in article); if, as Butterfield suggests (see citation in article), it's a prerequisite for complex multicellular organisms, it really does need explanation; it's included in The Major Transitions in Evolution. However you're right, it was the weakest section in the article. I've had a go at improving it, please let me know what you think.
 * There's a big debate about when metazoa appeared, with mol phylo research generally suggesting dates hundreds of MY before the earliest known fossils. That's too big a topic for this article, which is already a monster. If the first metazoa appeared after the last snowball earth episode (or slushball or whatever), these glaciations are probably irrelevant. If the first metazoa appeared earlier, there's a further debate about whether these glaciations retarded or accelerated evolution of metazoa. I think this is yet another topic that doesn't make the cut.
 * Re "Anapsids; whether turtles belong here is debated", the problem is that "anapsid" is itself ambiguous. We know that the earliest and presumably basal sauropsids (Late Carboniferous) had anapsid skulls, and that's the sense in which the diagram uses "anapsid". Turtles have anapsid-like skulls, but the earliest known fossils are Triassic (Odontochelys, with teeth and a plastron but no carapace; as of this year Proganochelys is no longer the earliest known), and there is a debate about whether they are descendants of the Permian anapsids (procolophonids, millerettids, protorothyrids, pareiasaurs, etc.) or of a diapsid lineage that secondarily lost the fenestrae. Because of this debate, it would be out of order to give turtles a specific place in the cladogram, but equally wrong to omit them. "Anapsids; whether turtles belong here is debated" is the best solution I could come up with for this dilemma. If you can suggest alternatives I'd be interested. --Philcha (talk) 12:08, 22 December 2008 (UTC)

Early sponges
There's an interesting paper in the latest Nature, Fossil steroids record the appearance of Demospongiae during the Cryogenian period, reporting evidence for sponges dating back 635 Mya, which would make it by a substantial margin the earliest evidence for animal life. I wonder whether this is solid enough to go into the article? Looie496 (talk) 17:16, 5 February 2009 (UTC)


 * The claim in the title is about as solid as an unset jello. See the commentary for reasons to treat its conclusions with a rather hefty pinch of salt. [Although there are some interesting aspects to the paper, as said commentary mentions] Martin  (Smith609 – Talk)  19:46, 5 February 2009 (UTC)

History of the Earth
As the article is already too long, a large section about the history of the Earth is quite unnecessary here. I have been bold enough to remove it. --Sir48 (talk) 16:02, 17 March 2009 (UTC)


 * And I've done the 2nd part of WP:BRD, reverted the removal. The Earth's age and when it became habitable are important, e.g.: if someone claimed signs of life before when the Earth is thouhg to have become habitable or before astronomical evidence indicates it was formed, one would know something was wrong (this is not totally ridiculous, in the 1990s the estimated ages of some stars were older than most estimates of the age of the universe!); if the earliest convincing evidence of life is 3 BYA (and possibly 3.4 BYA, it he most recent claim cited is correct) and the Earth finally became habitable abouit 3.8 BYA, the emergence of life cannot have been a very improbable process while if the Earth was thought to be habitable e.g. 10 BYA either the emergence of life is very improbable or we need new hypotheses about how life may have arisen. The GA reviewer had no problem at all with the article's inclusion of a brief history of the pre-biotic Earth. --Philcha (talk) 20:11, 17 March 2009 (UTC)
 * Why would the age of the oldest rocks, the formation of the Moon, the late heavy bombardment etc. - topics that are covered fully in history of the Earth, Age of the Earth, and many other articles - be of interest here? That unnecessary section had better be dropped, especially since the article is already much too long. Two lines or so about the age of the Earth and a link to these articles would be sufficient.
 * I've noticed that I mistakenly removed the timeline also. That should stay, of course, and it could be positioned nicely in the empty space to the right of the TOC. --Sir48 (talk) 20:59, 17 March 2009 (UTC)
 * I agree with Philcha that some coverage of this is needed, but I'm sympathetic to the notion that it could be tightened up a bit. It would help if the section would more explicitly state why it is relevant. Looie496 (talk) 22:08, 17 March 2009 (UTC)


 * I disagree with "Two lines or so about the age of the Earth and a link to these articles would be sufficient" because many books still talk of a "Hadean era" in the literal meaning of the phrase - in fact I thought of the surface as bombarded and often largey molten for most of the first 800 MY (4.6 BYA to 3.8 BYA) until I started researching. One fundamental problem is the extreme uncertainties about what happened. For example IIRC it's been suggested that life may have first arisen not long (geologically) after the first atmosphere and oceans formed about 4.4 BYA. If so, either the Late Heavy Bombardment exterminated it or hyperthermophile organisms living deep in rocks (possibly archea) may have survived and some of these may have been ancestors of all modern life. Making the section shorter would give a false impression of certainty. Even the impact that formed the Moon is relevant if you know a bit of astrobiology - see e.g. Rare Earth hypothesis - which concentrates too much on axial tilt and omits the consequences of knocking 70% of the continental crust into space: room for the oceans to form, otherwise the Earth would have been almost entirely covered by shallow seas; possibly necessary for plate tectonics and thus for the carbon cycle, without which life as we know it would be impossible because all the CO2 would eventually be locked up in carbonate rocks.
 * "if the section would more explicitly state why it is relevant" it would about double in size, because it would have to go into the possibilities outlined above.
 * In the GA review we discussed the possibility of splitting the article chronologically, but concluded someone would then want an overview article, and we'd be back to square 1. Considering it covers 4.6 BY it's really quite brief.
 * In the longer term we need to consider what the overall package of linked articles should be that explains how the world we know came into existence. The chemical evolution of the oceans and atmosphere alone is a huge topic - and unfortunately one in which views have long been liable to rapid changes.
 * Perhaps one of you would like to draft a suggested new version of the section "Earliest history of Earth" at e.g. a sub-page of this Talk page and then invite discussion when you're ready. --Philcha (talk) 23:40, 17 March 2009 (UTC)

--Philcha (talk) 23:40, 17 March 2009 (UTC)
 * Dear all, I would like to make some comments on what is said above:
 * The surface of the Earth (and its mantle) can never have been completely molten, unless a giant impact is postulated. In fact, the composition of some of the oldest rocks from the Moon (a very primitive composition) can only be explained when the Moon was at one stage completely molten. This is, in its turn, seen as evidence for a giant impact!
 * Life in whatever form would not have survived such an impact, so the first life on Earth must have lived after the impact, probably when the oceans and (second) crust and atmosphere were formed. (source needed...)
 * By "oceans and (second) crust and atmosphere" do you mean before or after the presumed imapct that created thwe Moon? If after, what's the evidence that oceans, crust and atmosphere existed before the (presumed) impact? And if these existed, would their composition have supported anythign we'd recognise as life? --Philcha (talk) 11:14, 18 March 2009 (UTC)
 * I meant after the impact. It is known from the isotopic composition of the atmosphere that it formed sometime after the formation of the Earth itself (it is a secondary feature - which is in itself again evidence for an impact). There are several reasons why it is assumed the Earth had a primary atmosphere as well. Some of these arguments are: 1) the composition of the inner Solar Nebula (there were enough gases that would have been attracted to the proto-Earth); 2) the fact that Venus and Mars have a (supposedly primary) atmosphere.
 * Before the impact, the Earth cannot have been completely molten since that would require an enormous amount of free energy. So it must have had a (probably basaltic) crust. The question if life could have existed before the impact, is a scientifically difficult one. It depends on what and how long life needs to form, develop, etc. Things about which very little is known for certain. Interestingly, if life formed on the proto-Earth, there is no reason why it couldn't have formed on early Venus and Mars as well. These planets are thought to have been very similar environments just after the formation of the Solar System (though they are hostile to all Earthly life now). Woodwalker (talk) 17:34, 18 March 2009 (UTC)
 * I doubt if it is necessary to mention the impact in this article, I think mentioning that the Earth was supposedly completely molten at one stage suffices: life on Earth was at that stage not possible.
 * The Late Heavy Bombardment is seen as a major influence on the earliest evolution of life (source needed...), therefore I think it should be mentioned.
 * Geochemists all agree that by the time of the impact (less than 100 Ma after the formation of the Solar System) the chemical differentiation between crust and mantle was largely non-existent. "knocking 70% of the continental crust into space" was impossible, because no continental crust existed in those times.
 * Sources I've read (but never bookmarked or noted in any of my sub-pages, silly me) have suggested that the relative paucity of Earth's contintental crust leave basins for the oceans, and that without these Earth would be mainly shallow seas - which might be OK for life but not for technology, as mastery of fire would be near impossible. These sources said that the paucity of contintental crust is a result of the impact. Have I got that right, and are there other important views? --Philcha (talk) 11:14, 18 March 2009 (UTC)
 * I never read about this hypothesis and I am interested in your sources. The formation of continental crust and its timing is an interesting problem in Archaean geology. As far as I know, most authors seem now to agree that continental crust began to be more common at the end of the Archaean eon (from about 3.4 Ga), more than a billion years after the formation of the Earth. This is because the formation of continental lithosphere (unlike the formation of oceanic lithosphere) is by no means a simple process. It requires multiple phases of partial melting and probably a lot of time. The high heat flow and fast mantle convection of the Archaean Earth may have prevented it, with the exceptions of several small Archaean cratons that go back to about 3.8 Ga. So, in the Archaean the Earth would have had small and few continents - according to current scientific consensus.
 * That wouldn't necessarily mean the whole planet was covered in a shallow ocean. Basaltic oceanic crust can have significant differences in density and therefore in relief (that's why mid-oceanic ridges are higher than oceanic basins). One paper I read (de Wit, 1998) suggested the mid-oceanic ridges could have been above the water in the beginning. Which in its turn would have prevented continental crust to form (hydrated oceanic crust is needed in the process, that's supposedly why Venus has little continental crust). Woodwalker (talk) 17:34, 18 March 2009 (UTC)
 * As I recall it, the moon is pretty much completely composed of crust material (feldspars etc) and very little mantle material (olivine etc), for what it's worth. Martin  (Smith609 – Talk)  21:28, 18 March 2009 (UTC)
 * The bulk Moon composition is assumed to be similar to the primitive mantle (= Earth's crust + mantle without core). There was no chemical differentiation between the crust and mantle at the time of the giant impact. Woodwalker (talk) 21:54, 18 March 2009 (UTC)
 * (EC)OK, either I misunderstood or what I read was way out-of-date. And my concern with continents is rather anthropocentric, as life on Earth appears to have been entirely marine for at least 5/6 of its history :-)
 * IIRC the Moon is important in other ways: its creation of tides created the opportunity for gradual adaptation to life on land (mre anthropocentrism!); and it's said to stabilise the axial tilt (I don't know the mechanism). An unstable axis would lead to chnages in the pattern of seasons - in the worst case the axis might tilt close to the plane of the Earth's orbit, like that of Uranus, giving most of the earth 6-month "days" and 6-month "nights". This suggests the Moon's stabilising influence may be quite imprtant for the evoltion of life here. Can anyone provide further info, with sources? --Philcha (talk) 21:35, 18 March 2009 (UTC)


 * Plate tectonics is not a prerequisite for large scale volcanism and influx of CO2 into the atmosphere (see Venus for a volcanically active planet without plate tectonics).
 * My understanding (possibly wrong) is that the sustainability of the carbon cycle depends on subduction of carbonates created by weathering, and subsequent recycling of CO2 via volcanoes - otherwise CO2 would be depleted as reserves ran down, photosynthesis woudl bewcome more difficult, and ice ages would become increasingly common as the greenhouse effect weakened. Have I understood this correctly? --Philcha (talk) 11:14, 18 March 2009 (UTC)
 * I don't know enough about geochemistry to exclude this hypothesis. I know degassing of the mantle is a major flux of CO2 to the atmosphere, so volcanic recycling by plate tectonics is not the only flux. There may also be other mechanisms beside plate tectonics by which carbonates can be molten or degassed and carbon be recycled into the atmosphere. Some carbonate minerals are stable at very high pressures though. Woodwalker (talk) 17:34, 18 March 2009 (UTC)
 * About the general structure of the article: I'd say the current hybrid structure is excellent. The article describes processes and mechanisms and at the same time it treats the main developments in a chronological order. Actually, my handbook on Earth history (Stanley) is split in two: it has general chapters first, then chronological chapters which treat the main developments of each age. Regards, Woodwalker (talk) 10:37, 18 March 2009 (UTC)


 * Hi, Woodwalker, I know you're strong on geology, so if you can clarify things, with sources, that would be great. Then we can see how much of that should go in this article, assuming that the detailed version should be in History of the Earth. I've posted some questions under items in your bullet list. --Philcha (talk) 11:14, 18 March 2009 (UTC)
 * Hi Philcha, I answered your questions. For more definite information, good sources are needed. I will try to find some later on, when I'm in the library here. Woodwalker (talk) 17:34, 18 March 2009 (UTC)

These are all very interesting subjects and intriguing details that I enjoy reading. My point is, however, that they do belong to other articles. Since this article is about the evolution of life (an enormous subject in itself and otherwise excellently described here imho), too much emphasis is given to the origin of life. The starting point should be the fact that life had already somehow originated (and similarly that the Earth existed).

Theories about the origin of life and the prevailing conditions in Hadean are covered by the article abiogenesis and the section about Earth's early history is covered by History of the Earth, Geological history of Earth, and other articles.

This is the reason why I propose that section 1: Earliest history of Earth should be left out entirely (leaving only a reference to the main article), and that section 3: Origins of life on Earth should be reduced considerably by mostly summarizing the abiogenesis article. This would improve the focus of this article, which is evolution rather than origin, and also the division of subjects between articles. --Sir48 (talk) 12:29, 19 March 2009 (UTC)


 * For what it's worth, I am another person who likes the article the way it is. In a perfect world, the diagram "History of Earth and its life" would fit within the "Earliest history of Earth" section, but it's fine, as is. A reader can easily skip the section, but I suspect most would return to it as soon as they started reading the next section about when the earliest life is thought to have occurred. Johnuniq (talk) 10:41, 20 March 2009 (UTC)

Article disgusts me...
For one, it automatically assumes evolution is true... --208.126.51.56 (talk) 09:38, 11 May 2009 (UTC)

I shall attempt to fix it.

Bless all.


 * Please bear in mind that there is also a Wikipedia article on Creationism. If you can find suitable published references you could create a new article called something like Creationist history of life, but this article on Evolutionary history of life 'assumes evolution is true' because it is about an aspect of the scientific theory of evolution. And that in turn is entirely evidence-based. --Chris Jefferies (talk) 13:10, 11 May 2009 (UTC)


 * See Talk:Evolution/FAQ. Tim Vickers (talk) 16:00, 11 May 2009 (UTC)


 * (I have removed a useless inflammatory comment that was added here. People who really want to see it can look at the page history.) Looie496 (talk) 16:39, 17 May 2009 (UTC)

Photosynthetic efficiency
This edit adds a w-link to Photosynthetic efficiency in "Life on land required plants to become internally more complex and specialized: photosynthesis was most efficient at the top; roots were required ...". I think the lnk is irrelevant because: I am therefore undoing the edit. ---Philcha (talk) 06:11, 18 June 2009 (UTC)
 * Photosynthetic efficiency is about the % of solar energy received that is converted to biochemical energy.
 * "... photosynthesis was most efficient at the top ..." is about easier and more secure access to light at the the top. The relevant measure of efficiency here is the energy gained in relation to the energy spent in building leaves.

Evolution of sex
The current text reads:
 * 1) The Red Queen Hypothesis suggests that sexual reproduction provides protection against parasites, because it is easier for parasites to evolve means of overcoming the defenses of genetically identical clones than those of sexual species that present moving targets, and there is some experimental evidence for this.
 * 2) However there is still doubt about whether it would explain the survival of sexual species if multiple similar clone species were present, as one of the clones may survive the attacks of parasites for long enough to out-breed the sexual species

In which 1 and 2 combined are presented as a dilemma. It seems the first sexually reproducing eucaryotes had a disadvantage because of their slower breeding rate, so how could they evolve at all? However, many "primitive" eucaryotes (protists) reproduce themselves in two ways: sexually and asexually. Suppose the first sexual organisms were also capable of cloning themselves like their ancestors. The supposed dilemma did not exist: the first population to reproduce sexually had a bigger fittness than its neighbours: not only did it possess the breeding advantage, once in a while it could increase its genetic variation and thus increase its defence against parasites. Woodwalker (talk) 15:45, 27 July 2009 (UTC)


 * This is not the right article to go into this in detail - the article is already quite long, and e.g Sexual reproduction would be a better place for greater detail. You're quite right that there are many intermediate options between entirely asexual and entirely sexual reproduction, and they are not limited to sigle-celled eucaryotes - for some example I remember reading that many aphid species reproduce asexually in summer, as this is the fastest way to reproduce during the good times, but sexually in early autumn, as the greater variation will improve the chances that some of a lineage will survive the hardships of winter. --Philcha (talk) 15:57, 27 July 2009 (UTC)
 * Hi Philcha, thanks for your quick answer. I think you misunderstood me. I don't want more details, if something is done I'd rather propose to delete a sentence or so. I noticed the current text is misleading in presenting a dillema which doesn't exist. I didn't know about the reasons for seasonal sexual behaviour in aphids, it's interesting! Best regards, Woodwalker (talk) 12:40, 28 July 2009 (UTC)
 * Hi, Woodwalker, the dilemma does exist, according to the sources. To take this from the top: sexual repro is dominant in all multi-celled taxa above species level, despite the fact that they have slower reproduction than clones (that's the real dilemma); single-factor explanations of the emergence and dominance of sexual repro have never quite made their case; the Red Queen Hypothesis comes very close to succeeding, but has a loophole - parasites may kill off a single competing clone lineage, but may be unable to kill all of several simultaneous clone lineages before the clones outbreed the sexual lineage. --Philcha (talk) 13:22, 28 July 2009 (UTC)
 * Hi Philcha, I appreciate your WP:NOR, but I don't think the sources say there is a paradox. For example, Otto & Gerstein (2006, one of the two references used in this section that are more than just a source for a fact) present the paradox, then go on explaining why it is an apparent paradox. My own book on evolutionary biology, Freeman & Herron (2003, 3rd ed.) begin by mentioning the aphids:
 * ...Why not avoid all the trouble and risk and simply reproduce asexually instead? This question sounds odd to human ears, because we have no choice: We inherited from our ancestors the inability to reproduce by any other mean than sex. But maby organisms do have a choice, at least in a physiological sense: They are capable of both sexual and asexual reproduction and regularly switch between the two. Most aphid species, for example, have spring and summer populations composed entirely of asexual females.... In the fall, aphids change modes, producing males and sexual females...
 * I wonder if they used this passage for the same reason I mentioned organisms that reproduce in more than one mode. They continue with explaining John Maynard Smith's simple mathematical model presents us with a "mathematical paradox of sexual reproduction". The model is based on two presumptions: 1) A female's reproductive mode doesn't affect the number of offspring she can make; 2) A female's reproductive mode doesn't affect the probability that her offspring will survive. But, unlike this article, Freeman and Herron continue their discussion:
 * Obviously, sex must confer benefits that allow it to persist in spite of the strong reproductive advantage offered by parthenogenesis. But what are these benefits? The mathematical logic of Maynard Smith's model is correct, so the benefits of sex must lie in a violation of one or both of the assumptions... The first assumption... is violated in species in which the fathers provide resources or other forms of parental care essential for producing young... Species in which female reproductive success is limited by male parental care certainly exist. However, species with male parental care are in the minority... A general advantage to sex is thus more likely to be found in the violation of the second assumption...
 * Prove for this last sentence is then offered by giving the results of an experiment by Dunbrack et al. (1995). The discussion continues:
 * The next question is: Why? The only inherent difference between offspring that a female makes sexually versus asexually is that asexual offsrping are genetically identical to their mother and to each other, whereas sexual offspring are genetically different from their mother and from each other.
 * Freeman & Herron give two potential answers to this question, the first involving genetic drift, the second involving natural selection.
 * I am sure you have read this (or a similar discussion in another book/paper). My reason for showing you is that the current text is not a good abstract of current biological knowledge. It just gives the reader the first half of the discussion and leaves the second half out. In this way it presents the reader with a dilemma, that can in fact be solved. I hope you see what I mean! :-) Best regards, Woodwalker (talk) 10:45, 30 July 2009 (UTC)

Back on the lead again
Looking through the talk page there's been quite a lot of discussion on the lead in the past, but it doesn't seem like much has been done to rectify the problems. I'd like to bring it to attention again. I suggest replacing the first paragraph with the following:

''The evolutionary history of life on Earth traces the processes by which living and fossil organisms evolved. It stretches from the origin of life on Earth, thought to be around 3.5 Ga (billion years) ago, to the present day. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species have diverged through the process of evolution .''

Thoughts? I'll offer some of my reasoning to back up the changes. Firstly, the discussion of abiogenesis and panspermia seems out of place here - I think it's hard to argue that it is even relevant to the topic - let alone should be given such significance in the article. Secondly, I believe a broad statement relating to the similarities between organisms is more appropriate in the lead than talking specifically about chemical processes - this is more along the lines of summaries in other evolution articles. Lastly, the structure doesn't really make sense as is, particularly "which indicates that all modern organisms share a common ancestor. However even the simplest modern organisms are too complex to have emerged directly from non-living materials" - the second sentence isn't a refutation of the first so the however seems inappropriate and without it, I don't see how the point is relevant.

Grateful for any feedback, thanks.Cubathy (talk) 14:55, 4 December 2009 (UTC)
 * I agree with all of your reasons and the proposal seems an improvement to me. The reference to Futuyma's book is super, it's exactly the type of source you'd expect for an article like this. Woodwalker (talk) 12:27, 10 December 2009 (UTC)

Amniote cladogram
I've reverted these 2 edits about turtles. The cladogram was already large, and the changes made the cladogram wider, sqeezing the text uncomfortably. The major difficult in working this article is to be concise, as it covers 4.6 billion years. If you can add max 10 words about turtles in the text that would be good. --Philcha (talk) 05:41, 28 December 2009 (UTC)

Problem
If carbon dating relies on an assumption, how can it be accurate? Several trees on Mt St Helens were knocked into a pond - trees that man had watched grow from saplings to trees, watched fall into this pond. Carbon dating said they were a few million years dead. Anyone can argue with me, but if you're looking for a belief based in fact, Christianity is the one absolute truth. I know many people delete this type of comment, or say it's silly or wrong or biased, but I know it is true. —Preceding unsigned comment added by Ork rule1 (talk • contribs) 15:00, 30 August 2010 (UTC)

Another problem: This article is stated blatantly as the one and only truth. This is biased and Wikipedia doesn't allow for bias. —Preceding unsigned comment added by Ork rule1 (talk • contribs) 15:10, 30 August 2010 (UTC)


 * This comment (in additional to being false) has nothing to do with improving the article. Please comment on other forums, and leave Wikipedia alone, unless you are willing to follow Wikipedia policies.  — Arthur Rubin  (talk) 15:14, 30 August 2010 (UTC)

So you are telling me to follow Wikipedia policies, when this article is biased and you are keeping it that way? Ork rule1 (talk) 15:25, 30 August 2010 (UTC)
 * If you can provide some reliable sources that confirm that Christianity is the one absolute truth, please cite them. Otherwise Conservapedia might be more your bag.  ...  disco spinster   talk  15:30, 30 August 2010 (UTC)

Evolution of the Genetic Code
It is more one topic for this article?

There are many theories, and some of the more cited are about mathematical models and symmetry hypothesis (broken symmetry approximately 1 billion years ago)... See:
 * Phys. Rev. Lett. 71, 4401–4404 (1993) "Algebraic model for the evolution of the genetic code". Abstracts at http://prl.aps.org/abstract/PRL/v71/i26/p4401_1
 * S. Osawa,Evolution of the Genetic Code (Oxford University Press, 1995)
 * ... —Preceding unsigned comment added by 189.18.228.11 (talk) 16:47, 22 October 2010 (UTC)


 * Hi, Evolutionary history of life is already a long article which includes may of sub-topics. Have you considered looking at articles and discussions (Talk) about genetics? --Philcha (talk) 15:34, 23 October 2010 (UTC)


 * Genetic code has a "theories on the origin" section that could be expanded, or if somebody wanted to write a really thorough account, a separate Evolution of the genetic code article would be a nice thing to have. Looie496 (talk) 18:07, 23 October 2010 (UTC)

Thousand million
Why does this article use "thousand million"? Is the word "billion" too difficult to understand?76.17.118.157 (talk) 00:39, 25 November 2010 (UTC)
 * The answer is yes, actually. See long and short scales.  In British English, a billion is a million million. Looie496 (talk) 01:50, 25 November 2010 (UTC)

Edits by 96.227.161.79
I removed the following additions from the article. Someone might want to rework the article accordingly. --Fama Clamosa (talk) 11:16, 3 December 2010 (UTC)


 * The printed version of this article has annoying http annotations attached to all geological dates -- Charles Parsons
 * Printed version of "One possible family tree ..." diagram is half missing. -- Charles Parsons

- Here is an example of what Mr. Parsons is talking about, I believe:
 * The evolutionary history of life on Earth traces the processes by which living and fossil organisms evolved. It stretches from the origin of life on Earth, thought to be over 3,500 (http://toolserver.org/~verisimilus/Timeline/Timeline.php?Ma=3,500) million years ago, to the present day. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species have diverged through the process of evolution.[1]

That link seems to come from the template. It will take someone with stronger wiki-fu than me to sort this out. __ Just plain Bill (talk) 15:08, 3 December 2010 (UTC)
 * I have asked about this at WP:VPT. Johnuniq (talk) 03:19, 4 December 2010 (UTC)
 * That was quick. Gadget850 has fixed the problem, as can be seen at printable version.
 * Re the other problem (half diagram missing), I have not looked at that matter, but (if precise information including browser version is provided), the people at WP:VPT are very helpful. However, my guess is that not all problems are fixable in practice, given the wide range of browsers and page complexities. Johnuniq (talk) 07:28, 4 December 2010 (UTC)

2011
i swear the dates are wrong on this article. the article claims that the earth is 4,500 million years old, when its realy 4.5 billion years old. how could these errors have gone without fixing? —Preceding unsigned comment added by 144.62.230.86 (talk) 18:23, 14 February 2011 (UTC)
 * As explained above (in the section), it's unclear what "billion" even means. Based on your US IP, it's a bit concerning you don't know that 4 thousand million is the same as 4 billion in normal American-style counting. But if that's not your usual counting style, no problem--now you know there are two different ones. And it means you've apparently been misled by some other sources you have read...the first few cited in our article actually do talk in "thousand million" specifically to avoid confusion, even if popular-press newspapers use "billion" (without explicitly defining that means). DMacks (talk) 18:33, 14 February 2011 (UTC)
 * Whether or not they know what it means, "thousand million" is going to be very weird to most Americans. — Preceding unsigned comment added by 142.176.114.76 (talk) 22:37, 19 March 2014 (UTC)
 * Good thing this isn't "Americanopedia" or something like that then. ;) Swedra (talk) 21:51, 19 September 2015 (UTC)

Concerns about the new section: Evolution of terrestrial antioxidants
A new section was added today. My take is that the material is highly speculative and in any case not at a level suitable for this article -- I am inclined to remove it. Any other opinions? (The edit was made from a dynamic IP address, so there is no way to notify the editor of this discussion.) Looie496 (talk) 13:39, 5 October 2011 (UTC)


 * It looks interesting, but has some problems:
 * No citation in the 1st para. --Philcha (talk) 14:30, 5 October 2011 (UTC)
 * Too much about oxidants in general. --Philcha (talk) 14:30, 5 October 2011 (UTC)
 * Some parts are about the appearance of angiosperm plants, much later. --Philcha (talk) 14:30, 5 October 2011 (UTC)


 * Isn't it disproportionately long for an article on the history of life in general? And I also wonder whether the evidence given is adequate for all that is said. How about paring it down drastically in this article, moving most of it to another article (such as creating a subheading for evolutionary history in the article Antioxidant}, or even a completely new article Evolution of antioxidants)? It looks interesting, but I'm not at all familiar with this topic. TomS TDotO (talk) 10:58, 7 October 2011 (UTC)

Millions vs billions of years
I noticed that years are always referred to in millions instead of billions in this article. For example, the Earth formed 4,500 million years ago instead of 4.5 billion years ago. I find this quite annoying as every other article always uses billions of years. I am going to change everything that has thousands of millions of years and change it to billions. Cadiomals (talk) 19:07, 19 November 2011 (UTC)
 * The reason I'm making a big deal of this is because no other article about the history of earth uses thousands of millions of years, and I think this one should adhere to the status quo to make things less confusing. The person has previously argued that million million is the way it is used in Britain, but even articles that use British English have billions of years.
 * This is a painstaking process since its throughout the entire article, so you are welcome to help me if you spot any I missed.
 * As addressed above, the use of 'Billion' can cause confusion. It may be used in other articles, but that doesn't really make it the correct usage.  If you are wanting to get this article up-to-date, I suggest using Ga and Ma.  Those SI units are understood in any English variation.
 * Seems fair. You're right, Ga and Ma units are more up-to-date. I just did the tedious work of converting all the "billions of years" ones to Ga. Would you be willing to help me by converting the "millions of years" ones to Ma to even it out? If not, I'll have to do it a bit later because I'm too lazy to do it all in one sitting. Cadiomals (talk) 19:53, 19 November 2011 (UTC)
 * I made an effort to update all of the Millions, and updated the templates to continue to point into the timeline. I also added period names so we could turn on the ±error option if wanted.  I'll have to look at the template:ma a little closer though, as some didn't seem to work.  Please review again yourself and see if I missed any. Tgeairn (talk) 21:10, 19 November 2011 (UTC)
 * Thank you for your work. I'm glad we could come to an agreement on which units to use. Everything looks fine. Thanks! Cadiomals (talk) 23:59, 19 November 2011 (UTC)
 * Would most people really know what GA is? — Preceding unsigned comment added by 142.176.114.76 (talk) 22:39, 19 March 2014 (UTC)

Sorry to be pedantic but in strict British English, 1000 million is a milliard (ie 10E9), and a billion is a million million (10E12). However the American English billion (10E9) has now almost entirely replaced the milliard, and most people wouldn't know a milliard if it leapt up and bit them, to paraphrase P G Wodehouse...185.12.191.170 (talk) 13:18, 12 March 2015 (UTC)

Problem with Origins of life on earth section
Hi, what is with the statements made in the "Origins of life on earth" section. Specifically the statements that read "cells far too complex to have not been made by god." Why is this even in there? Those statements shouldn't be in there as if they are FACTS. They should be re-worded to show that they are in fact purely religious as they currently stand. "Cells far too complex to have arisen directly from non-living materials." Basically means that the cells arose from either living materials, which is nonsense. Or a god or gods, which is just as preposterous. 142.161.62.185 (talk) 03:55, 20 June 2012 (UTC) Barry J French
 * I'm sure the intent was not to convey a religious message. The point that the sentence is trying to make is that bacteria could not have arisen by simple forms of organic chemicals clumping together or anything like that -- the immediate precursors must also have been very complex.  I agree that the idea could be expressed better.  And I don't know where you get "cells far too complex not to have been made by god" -- you put that in quotation marks, but I can't find it in the article. Looie496 (talk) 04:44, 20 June 2012 (UTC)

Panspermia statement
The article contains the following statement:
 * There are three main versions of the "seeded from elsewhere" hypothesis: from elsewhere in our Solar System via fragments knocked into space by a large meteor impact, in which case the only credible source is Mars...

However, multiple publications suggest that microbiota may have been transported from Venus, which was not always so inhospitable having likely had oceans for 600 million to several billion years. Regards, RJH (talk) 20:11, 26 June 2012 (UTC)
 * I think you should feel free to alter the statement, using the best of your sources as a reference. Looie496 (talk) 03:52, 28 June 2012 (UTC)
 * Okay I've updated the article per your suggestion. Thank you for the response. Regards, RJH (talk) 23:44, 1 July 2012 (UTC)

Late evolution of oceanic life
Where this article seems perhaps a little weak is in its coverage of later sea-based life forms. There's a fairly strong land-based bias in the latter half of the article, and fish are barely mentioned except in the context of evolution into land dwellers. Regards, RJH (talk) 20:05, 10 July 2012 (UTC)

Evolutionary editors sort it out, if you can avoid Creationist baiting
Hi folks. Look, I don't really give a damn about ideological warfare, or the need for people to engage in baiting behaviour. I took care of the "contradictory" tag in a good faith edit. As they say in some countries, Blind Freddy can see that it was a non-issue, and that what was driving the tag was ideology. Hell, I saw all this crap circa late 1980s through mid 1990s: it's not new. Someone who is a regular here should simply add an appropriate caveat to the lede (as I did), and take out the "contradictory" tag. I have to tell you it's not a difficult task, and it's no big deal that evidence for X post period y is more reliable than evidence for x prior to period y: like this is standard stuff man.

We need to be extremely clear here. Certain ideological persuasions are NOT amenable to rational evidence, period. So don't get side-tracked. Sort it out if you can. Wotnow (talk) 02:38, 24 November 2012 (UTC)

Recent changes in the beginning of Humans section and Present
I believe as this is a article about evolution that Darwin, Wallace, and Chambers all need to be mentioned, and I decided to add it to the section labeled Humans as it alludes to humans evolving from apes I thought it seemed appropriate.

I also added an example of modern evolution in the present section as it is a example of how a population of a species can evolve differently in different enviroments. — Preceding unsigned comment added by RandomEditPro (talk • contribs) 23:41, 22 October 2013 (UTC)

Recent edits in the Humans section
The following has been added at the beginning of Evolutionary history of life.


 * The idea that, along with other life forms, modern-day humans evolved from a ancient, common ancestor was proposed by Robert Chambers in 1844 and taken up by Charles Darwin in 1871.

I think that this information properly belongs only in History of evolutionary thought; it is out of place in an article otherwise devoted to biology proper. History of evolutionary thought does need to be augmented to mention Chambers and the fact that Darwin did not discuss humans until The Descent of Man in 1871, but the material does not belong in Evolutionary history of life. The manner in which the hatnotes in Evolutionary history of life point to History of evolutionary thought needs some improvement. Peter Brown (talk) 15:06, 21 October 2013 (UTC)

Changes In The Present Section
I feel as though the section on the present is very loosely put together and seems to ramble. What is the goal of this section? Presenting examples of evolution in modern times? Pointing out recent studies? I am going to remove this section as it has no clear thesis or purpose, but I am welcome to ways to improve this article if the community can justify why it should stay, and would be glad to help. RandomEditPro (talk) 01:22, 22 November 2013 (UTC)

Change In Intro Paragraph
The paragraph states that until "recently" the oldest rocks were believed to date 3.8 billion years ago. I added a citation specifying the exact date the discovery was made dating the oldest rocks to over 4 billion years. — Preceding unsigned comment added by RandomEditPro (talk • contribs) 00:17, 1 November 2013 (UTC)

Recent edits by Venturi Seba


I removed the above because of sourcing issues. User: Venturi Seba appears to be citing his own work, which constitutes a WP:COI. However, I would like other editors to review this section. --Harizotoh9 (talk) 07:15, 18 March 2014 (UTC)

Stupid cladograms

 * Sigh* Is it really that hard to find a proper phylogeny? If your confused, this article uses two of what I call "Linnean cladograms". One is in the "Early land vertebrates" section, the other in the "Dinosaurs, birds, and mammals. The former treats "labyrinthodonts" as valid (As does the text!), and anthracosaurs as sister to amniotes, when amniotes is within anthracosauria. The latter is even worse, with no less then 4 examples; FOUR. They are: A)Synapsids are a mess; Pelecosauria as a valid grouping (The "extinct pelecosaurs" label.), and a similar situation happens with the "extinct therapsids" label, finally, mammalia is within mammliaformes; B)"Lizards and snakes", snakes are derived lizards; C) The croc-line archosaurs have a similar situation to synapsida, seriously, why not just say crurotarsa and makes the two one ? ;D)(Byfar the worst.), Birds as sister to "other theropods", when avialae is the mot derived of those "other theropods" ; there is no excuse for separating avialae (Birds) from "other theropods" in 2014, and yet multiple Wikipedia articles do this.142.176.114.76 (talk) 22:58, 19 March 2014 (UTC)

Weight given to Panspermia
I've checked that the structure of the article have been like this for years but isn't this header hierarchy a bit UNDUE-y?


 * Origins of life on Earth
 * Life "seeded" from elsewhere (Panspermia)
 * Independent emergence on Earth (Abiogenesis)
 * (rest of the article)

Why are they both given the same level header as though they're equally valid and can even be compared like this? I plan to restructure it. Ugog Nizdast (talk) 17:50, 5 December 2016 (UTC)


 * Done. Also removed an unsourced statement implying it's equally valid. Ugog Nizdast (talk) 07:44, 14 December 2016 (UTC)

Oldest evidence of life
"The oldest undisputed evidence dates to 3 Ga." mentioned here seems to contradict the main article. See Talk:Abiogenesis. Ugog Nizdast (talk) 02:58, 10 December 2016 (UTC)

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Human evolution
Strictly speaking, humans are pretty irrelevant in the history of life. As such, I'm thinking the article gives too much weight to humanity in proportion to the rest of the article. Maybe trim the human section, remove the human outline, and then expand the rest of the article. Harizotoh9 (talk) 02:50, 2 March 2017 (UTC)

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Stromatolite
An argument which refutes the 2016 study, regarding the 3.7 billion years old Stromatolite. 112.165.80.174 (talk) 00:32, 19 October 2018 (UTC)

Should the "Humans" section become a subsection of "Dinosaurs, birds and mammals"?
Apokrif (talk) 21:01, 22 July 2019 (UTC)


 * I'm ambivalent: it technically could, on the other hand I also don't mind if it's a separate section, since the encyclopedia is for humans and so much has been written about humans independently... — Paleo  Neonate  – 01:48, 23 July 2019 (UTC)

Rename to "History of life"
I think we should make the title of this article a little more succinct, and simply call it "History of life". Many sources use the term "History of life". Very few use the term "Evolutionary history of life". Seems like there are compelling WP:PRECISE/WP:CONCISE and WP:COMMONNAME arguments. NickCT (talk) 15:55, 3 December 2020 (UTC)


 * Agree. Peter Brown (talk) 01:43, 4 December 2020 (UTC)