User:SLUEvolution/sandbox

Chapters:

1. Evolution Overview

2. Scientific Method

In science, words may have different meaning in comparison to how they are used colloquially. A prime example is the everyday use of the word “theory.” While a given person may use the “theory” to simply describe an idea or conjecture, a scientist uses the word “theory” to describe a hypothesis that has been thoroughly tested, demonstrated, and not falsified. The following terms have been taken from the Oxford and Merriam-Webster dictionaries: Hypothesis: a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation1

Theory: a plausible or scientifically acceptable general principle or body of principles offered to explain natural phenomena2

Law: a statement of fact, deduced from observation, to the effect that a particular natural or scientific phenomenon always occurs if certain conditions are present1

The laws of thermodynamics are important unifying principles of biology. These principles govern the chemical processes (metabolism) in all biological organisms.

The First Law of Thermodynamics, also know as the law of conservation of energy, states that energy can neither be created nor destroyed. It may change from one form to another, but the energy in a closed system remains constant.

Fact: a thing that is indisputably the case1

Science also takes a specific approach to logic and reasoning. There are two primary types of reasoning: inductive and deductive. Inductive arguments are either strong or weak, while deductive arguments allow for falsification. The latter is of particular importance; scientific hypotheses are generated with the goal of attempting to falsify them, as opposed to proving them.

The classic philosophical treatment of the problem of induction was given by the Scottish philosopher David Hume. Hume highlighted the fact that our everyday habits of mind depend on drawing uncertain conclusions from our relatively limited experiences rather than on deductively valid arguments. For example, we believe that bread will nourish us because it has done so in the past, despite no guarantee that it will do so. Hume argued that it is impossible to justify inductive reasoning: specifically, that it cannot be justified deductively, so our only option is to justify it inductively. Since this is circular he concluded that it is impossible to justify induction.3

However, Hume then stated that even if induction were proved unreliable, we would still have to rely on it. So instead of a position of severe skepticism, Hume advocated a practical skepticismbased on common sense, where the inevitability of induction is accepted.3 Inductive reasoning is also known as hypothesis construction because any conclusions made are based on educated predictions.[citation needed] As with deductive arguments, biases can distort the proper application of inductive argument, thereby preventing the reasoner from forming the most logical conclusion based on the clues. Examples of these biases include the availability heuristic, confirmation bias, and the predictable-world bias.

The availability heuristic causes the reasoner to depend primarily upon information that is readily available to him/her. People have a tendency to rely on information that is easily accessible in the world around them. For example, in surveys, when people are asked to estimate the percentage of people who died from various causes, most respondents would choose the causes that have been most prevalent in the media such as terrorism, and murders, and airplane accidents rather than causes such as disease and traffic accidents, which have been technically "less accessible" to the individual since they are not emphasized as heavily in the world around him/her.

The confirmation bias is based on the natural tendency to confirm rather than to deny a current hypothesis. Research has demonstrated that people are inclined to seek solutions to problems that are more consistent with known hypotheses rather than attempt to refute those hypotheses. Often, in experiments, subjects will ask questions that seek answers that fit established hypotheses, thus confirming these hypotheses. For example, if it is hypothesized that Sally is a sociable individual, subjects will naturally seek to confirm the premise by asking questions that would produce answers confirming that Sally is in fact a sociable individual.

The predictable-world bias revolves around the inclination to perceive order where it has not been proved to exist. A major aspect of this bias is superstition, which is derived from the inability to acknowledge that coincidences are merely coincidences. Gambling, for example, is one of the most obvious forms of predictable-world bias. Gamblers often begin to think that they see patterns in the outcomes and, therefore, believe that they are able to predict outcomes based upon what they have witnessed. In reality, however, the outcomes of these games are difficult, if not impossible to predict. The perception of order arises from wishful thinking. Since people constantly seek some type of order to explain or justify their beliefs and experiences, it is difficult for them to acknowledge that the perceived or assumed order may be entirely different from that they believe they are experiencing.4

Conversely, deductive reasoning, also called deductive logic, is the process of reasoning from one or more general statements regarding what is known to reach a logically certain conclusion.5 Deductive reasoning involves using given true premises to reach a conclusion that is also true. Deductive reasoning contrasts with inductive reasoning in that a specific conclusion is arrived at from a general principle. If the rules and logic of deduction are followed, this procedure ensures an accurate conclusion. An example of a deductive argument:

1.	All men are mortal.

2.	Socrates is a man.

3.	Therefore, Socrates is mortal.

The first premise states that all objects classified as "men" have the attribute "mortal.” The second premise states that "Socrates" is classified as a "man" – a member of the set "men.” The conclusion then states that "Socrates" must be "mortal" because he inherits this attribute from his classification as a "man.”

Deductive reasoning (also known as logical deduction) links premises with conclusions. If both premises are true, the terms are clear and the rules of deductive logic are followed, then the conclusion of the argument follows by logical necessity.

The law of detachment (also known as affirming the antecedent and Modus ponens) is the first form of deductive reasoning. A single conditional statement is made, and a hypothesis (P) is stated. The conclusion (Q) is then deduced from the statement and the hypothesis. The most basic form is listed below:

1.	P→Q (conditional statement)

2.	P (hypothesis stated)

3.	Q (conclusion deduced)

In deductive reasoning, we can conclude Q from P by using the law of detachment.6 However, if the conclusion (Q) is given instead of the hypothesis (P) then there is no valid conclusion.The following is an example of an argument using the law of detachment in the form of an if-then statement:

1.	If an angle A>90°, then A is an obtuse angle.

2.	A=120°

3.	A is an obtuse angle.

Since the measurement of angle A is greater than 90°, we can deduce that A is an obtuse angle.

The law of syllogism takes two conditional statements and forms a conclusion by combining the hypothesis of one statement with the conclusion of another. Here is the general form, with the true premise P:

1.	P→Q

2.	Q→R

3.	Therefore, P→R.

The following is an example:

1.	If Larry is sick, then he will be absent from school.

2.	If Larry is absent, then he will miss his classwork.

3.	If Larry is sick, then he will miss his classwork.

We deduced the final statement by combining the hypothesis of the first statement with the conclude that this could be a false statement. Deductive arguments are evaluated in terms of their validity and soundness. It is possible to have a deductive argument that is logically valid but is not sound. An argument is valid if it is impossible for its premises to be true while its conclusion is false. In other words, the conclusion must be true if the premises, whatever they may be, are true. An argument can be valid even though the premises are false. An argument is sound if it is valid and the premises are true. The following is an example of an argument that is valid, but not sound:

1.	Everyone who eats steak is a quarterback.

2.	John eats steak.

3.	Therefore, John is a quarterback.

The example's first premise is false – there are people who eat steak and are not quarterbacks – but the conclusion must be true, so long as the premises are true (i.e. it is impossible for the premises to be true and the conclusion false). Therefore the argument is valid, but not sound. In this example, the first statement uses categorical reasoning, saying that all steak-eaters are definitely quarterbacks. This theory of deductive reasoning – also known as term logic – was developed by Aristotle, but was superseded by propositional (sentential) logic and predicate logic.

Deductive reasoning can be contrasted with inductive reasoning, in regards to validity and soundness. In cases of inductive reasoning, even though the premises are true and the argument is "valid", it is possible for the conclusion to be false (determined to be false with a counterexample or other means). The scientific method uses inductive reasoning to generate hypotheses, while deductive reasoning is used to explain scientific results.

Scientific methodology has been practiced in some form for at least one thousand years and is the process by which science is carried out. Because science builds on previous knowledge, it consistently improves our understanding of the world. The scientific method also improves itself in the same way, meaning that it gradually becomes more effective at generating new knowledge. For example, the concept of falsification (first proposed in 1934) reduces confirmation bias by formalizing the attempt to disprove hypotheses rather than prove them.7

The overall process involves making conjectures (hypotheses), deriving predictions from them as logical consequences, and then carrying out experiments based on those predictions to determine whether the original conjecture was correct. There are difficulties in a formulaic statement of method, however. Though the scientific method is often presented as a fixed sequence of steps, they are better considered as general principles.8 Not all steps take place in every scientific inquiry (or to the same degree), and not always in the same order. As noted by William Whewell (1794–1866), "invention, sagacity, [and] genius" are required at every step9:

Formulate a question: The question can refer to the explanation of a specific observation, as in "Why is the sky blue?", but can also be open-ended, as in "Does sound travel faster in air than in water?" or "How can I design a drug to cure this particular disease?" This stage also involves looking up and evaluating previous evidence from other scientists, as well as considering one's own experience. If the answer is already known, a different question that builds on the previous evidence can be posed. When applying the scientific method to scientific research, determining a good question can be very difficult and affects the final outcome of the investigation.10

Hypothesis: Based on the knowledge obtained while formulating the question, a hypothesis is a conjecture that may explain the observed behavior of a part of our universe. The hypothesis might be very specific, e.g., Einstein's prediction of the orbit of Mercury, or it might be broad, e.g., unknown species of life will be discovered in the unexplored depths of the oceans. A statistical hypothesis is a conjecture about some population. For example, the population might be people with a particular disease. The conjecture might be that a new drug will cure the disease in some of those people. Terms commonly associated with statistical hypotheses are null hypothesis and alternative hypothesis. A null hypothesis is the conjecture that the statistical hypothesis is false, e.g., that the new drug does nothing and that any cures are due to chance effects. Researchers normally want to show that the null hypothesis is false. The alternative hypothesis is the desired outcome, e.g., that the drug does better than chance. A final point: a scientific hypothesis must be falsifiable, meaning that one can identify a possible outcome of an experiment that conflicts with predictions deduced from the hypothesis; otherwise, it cannot be meaningfully tested.

Prediction: This step involves determining the logical consequences of the hypothesis. One or more predictions are then selected for further testing. The less likely that the prediction would be correct simply by coincidence, the stronger evidence it would be if the prediction were fulfilled; evidence is also stronger if the answer to the prediction is not already known, due to the effects of hindsight bias (see also postdiction). Ideally, the prediction must also distinguish the hypothesis from likely alternatives; if two hypotheses make the same prediction, observing the prediction to be correct is not evidence for either one over the other. (These statements about the relative strength of evidence can be mathematically derived using Bayes' Theorem.)

Test: This is an investigation of whether the real world behaves as predicted by the hypothesis. Scientists (and other people) test hypotheses by conducting experiments. The purpose of an experiment is to determine whether observations of the real world agree with or conflict with the predictions derived from a hypothesis. If they agree, confidence in the hypothesis increases; otherwise, it decreases. Agreement does not assure that the hypothesis is true; future experiments may reveal problems. Karl Popper advised scientists to try to falsify hypotheses, i.e., to search for and test those experiments that seem most doubtful. Large numbers of successful confirmations are not convincing if they arise from experiments that avoid risk.11 Experiments should be designed to minimize possible errors, especially through the use of appropriate scientific controls. For example, tests of medical treatments are commonly run as double-blind tests. Test personnel, who might unwittingly reveal to test subjects which samples are the desired test drugs and which are placebos, are kept ignorant of which are which. Such hints can bias the responses of the test subjects. Failure of an experiment does not necessarily mean the hypothesis is false. Experiments always depend on several hypotheses, e.g., that the test equipment is working properly, and a failure may be a failure of one of the auxiliary hypotheses (see the Duhem-Quine thesis.) Experiments can be conducted in a college lab, on a kitchen table, at CERN's Large Hadron Collider, at the bottom of an ocean, on Mars (using one of the working rovers), and so on. Astronomers do experiments, searching for planets around distant stars. Finally, most individual experiments address highly specific topics for reasons of practicality. As a result, evidence about broader topics is usually accumulated gradually.

Analysis: This involves determining what the results of the experiment show and deciding on the next actions to take. The predictions of the hypothesis are compared to those of the null hypothesis, to determine which is better able to explain the data. In cases where an experiment is repeated many times, a statistical analysis such as a chi-squared test may be required. If the evidence has falsified the hypothesis, a new hypothesis is required; if the experiment supports the hypothesis but the evidence is not strong enough for high confidence, other predictions from the hypothesis must be tested. Once a hypothesis is strongly supported by evidence, a new question can be asked to provide further insight on the same topic. Evidence from other scientists and one's own experience can be incorporated at any stage in the process. Many iterations may be required to gather sufficient evidence to answer a question with confidence, or to build up many answers to highly specific questions in order to answer a single broader question. Therefore, science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.2

References:

1. Oxford Dictionary

2. Merriam-Webster Dictionary

3. Vickers, John. (2010). "The Problem of Induction" (Section 2). Stanford Encyclopedia of Philosophy.

4. Gray, Peter. (2011). Psychology. New York: Worth. Print.

5. Sternberg, R. J. (2009). Cognitive Psychology. Belmont, CA: Wadsworth. pp. 578. ISBN 978-0-495-50629-4.

6. Guide to Logic

7. Popper, Karl R. (1963). The Logic of Scientific Discovery.

8. Gauch, Hugh G., Jr. (2003). Scientific Method in Practice. Cambridge University Press, ISBN 0-521-01708-4.

9. History of Inductive Science (1837), and in Philosophy of Inductive Science (1840)

10. Schuster and Powers. (2005). Translational and Experimental Clinical Research.

11. Popper, Karl R. (2003). Conjectures and Refutations: The Growth of Scientific Knowledge, Routledge. ISBN 0-415-28594-1.

-EXAMPLE: scientific method applied to an evolutionary question

3. Historical Context of Evolutionary Thought (make chronological)

Anaximander - Ryan

Anaximander ( /əˌnæksɨˈmændər/; Greek: Ἀναξίμανδρος Anaximandros; c. 610 – c. 546 BC) was a pre-Socratic Greek philosopher who lived in Miletus, a city of Ionia; Milet in modern Turkey. He belonged to the Milesian school and learned the teachings of his master Thales. He succeeded Thales and became the second master of that school where he counted Anaximenes and arguably, Pythagoras amongst his pupils.

Among a multitude of other realms of science pondered, Anaximander speculated about the beginnings and origin of animal life. Taking into account the existence of fossils, he claimed that animals sprang out of the sea long ago. The first animals were born trapped in a spiny bark, but as they got older, the bark would dry up and break.[40] As the early humidity evaporated, dry land emerged and, in time, humankind had to adapt. The 3rd century Roman writer Censorinus reports: Anaximander of Miletus considered that from warmed up water and earth emerged either fish or entirely fishlike animals. Inside these animals, men took form and embryos were held prisoners until puberty; only then, after these animals burst open, could men and women come out, now able to feed themselves.[41] Anaximander put forward the idea that humans had to spend part of this transition inside the mouths of big fish to protect themselves from the Earth's climate until they could come out in open air and lose their scales.[42] He thought that, considering humans' extended infancy, we could not have survived in the primeval world in the same manner we do presently. Even though he had no theory of natural selection, some people consider him as evolution's most ancient proponent. (The theory of an aquatic descent of man was re-conceived centuries later as the aquatic ape hypothesis.) These pre-Darwinian concepts may seem strange, considering modern knowledge and scientific methods, because they present complete explanations of the universe while using bold and hard-to-demonstrate hypotheses. However, they illustrate the beginning of a phenomenon sometimes called the "Greek miracle": men try to explain the nature of the world, not with the aid of myths or religion, but with material principles. This is the very principle of scientific thought, which was later advanced further by improved research methods.

Aristotle - Craig

Aristotle (Ancient Greek: Ἀριστοτέλης, Aristotélēs) (384 BC – 322 BC)[1] was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings many subjects,including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology. Together with Plato and Socrates (Plato's teacher), Aristotle is one of the most important founding figures in Western philosophy. Aristotle's writings were the first to create a comprehensive system of Western philosophy, encompassing morality, aesthetics,logic, science, politics, and metaphysics.

Aristotle is the earliest natural historian whose work has survived in some detail. Aristotle certainly did research on the natural history of Lesbos, and the surrounding seas and neighbouring areas. The works that reflect this research, such as History of Animals, Generation of Animals, and Parts of Animals, contain some observations and interpretations, along with sundry myths and mistakes. The most striking passages are about the sea-life visible from observation on Lesbos and available from the catches of fishermen. His observations on catfish, electric fish (Torpedo) and angler-fish are detailed, as is his writing on cephalopods, namely, Octopus, Sepia (cuttlefish) and the paper nautilus (Argonauta argo). His description of the hectocotyl arm was about two thousand years ahead of its time, and widely disbelieved until its rediscovery in the 19th century. He separated the aquatic mammals from fish, and knew that sharks and rays were part of the group he called Selachē (selachians).2

Another good example of his methods comes from the Generation of Animals in which Aristotle describes breaking open fertilized chicken eggs at intervals to observe when visible organs were generated. He gave accurate descriptions of ruminants' four-chambered fore-stomachs, and of the ovoviviparous embryological development of the hound shark, Mustelus mustelus.3

Aristotle's classification of living things contains some elements which still existed in the 19th century. What the modern zoologist would call vertebrates and invertebrates, Aristotle called 'animals with blood' and 'animals without blood' (he was not to know that complex invertebrates do make use of hemoglobin, but of a different kind from vertebrates). Animals with blood were divided into live-bearing (humans and mammals), and egg-bearing (birds and fish). Invertebrates ('animals without blood') are insects, crustacea (divided into non-shelled – cephalopods – and shelled) and testacea (molluscs). In some respects, this incomplete classification is better than that of Linnaeus, who crowded the invertebrata together into two groups, Insecta and Vermes (worms).

For Charles Singer, "Nothing is more remarkable than [Aristotle's] efforts to [exhibit] the relationships of living things as a scala naturae."2 Aristotle's History of Animals classified organisms in relation to a hierarchical "Ladder of Life" (scala naturae), placing them according to complexity of structure and function so that higher organisms showed greater vitality and ability to move. Aristotle believed that intellectual purposes, i.e., final causes, guided all natural processes. Such a teleological view gave Aristotle cause to justify his observed data as an expression of formal design. Noting that "no animal has, at the same time, both tusks and horns," and "a single-hooved animal with two horns I have never seen," Aristotle suggested that Nature, giving no animal both horns and tusks, was staving off vanity, and giving creatures faculties only to such a degree as they are necessary. Noting that ruminants had multiple stomachs and weak teeth, he supposed the first was to compensate for the latter, with Nature trying to preserve a type of balance.4 In a similar fashion, Aristotle believed that creatures were arranged in a graded scale of perfection rising from plants on up to man, the scala naturae or Great Chain of Being.5 His system had eleven grades, arranged according "to the degree to which they are infected with potentiality,” expressed in their form at birth. The highest animals laid warm and wet creatures alive, the lowest bore theirs cold, dry, and in thick eggs.

Aristotle also held that the level of a creature's perfection was reflected in its form, but not preordained by that form. Ideas like this, and his ideas about souls, are not regarded as science at all in modern times.

He placed emphasis on the type(s) of soul an organism possessed, asserting that plants possess a vegetative soul, responsible for reproduction and growth, animals a vegetative and a sensitive soul, responsible for mobility and sensation, and humans a vegetative, a sensitive, and a rational soul, capable of thought and reflection.6

Aristotle, in contrast to earlier philosophers, but in accordance with the Egyptians, placed the rational soul in the heart, rather than the brain.4 Notable is Aristotle's division of sensation and thought, which generally went against previous philosophers, with the exception of Alcmaeon.7

References:

1. Düring, Ingemar. (1957). Aristotle in the Ancient Biographical Tradition. Göteborg, p. 253.

2. Singer, Charles. A short history of biology. Oxford 1931.

3. Kearns, Emily. (1996). "Animals, knowledge about," in Oxford Classical Dictionary, 3rd ed., p. 92.

4. Mason. A History of the Sciences. pp. 43–44.

5. Mayr. The Growth of Biological Thought. pp. 201–202.

6. Aristotle, De Anima II 3

7. Guthrie. A History of Greek Philosophy. Vol. 1, pp. 348.

John Ray - Jesse

John Ray (29 November 1627 – 17 January 1705) was an English naturalist, sometimes referred to as the father of English natural history. He published important works on botany, zoology, and natural theology. His classification of plants in his Historia Plantarum, was an important step towards modern taxonomy. Ray rejected the system of dichotomous division by which species were classified according to a pre-conceived, either/or type system, and instead classified plants according to similarities and differences that emerged from observation. Thus he advanced scientific empiricism against the deductive rationalism of the scholastics.

Ray was the first person to produce a biological definition of what a species is. This definition comes in the 1686 History of plants: "... no surer criterion for determining species has occurred to me than the distinguishing features that perpetuate themselves in propagation from seed. Thus, no matter what variations occur in the individuals or the species, if they spring from the seed of one and the same plant, they are accidental variations and not such as to distinguish a species... Animals likewise that differ specifically preserve their distinct species permanently; one species never springs from the seed of another nor vice versa".[7]

Ussher - Laura

James Ussher (sometimes spelled Usher, 4 January 1581 – 21 March 1656) was Church of Ireland Archbishop of Armagh and Primate of All Ireland between 1625 and 1656. He was a prolific scholar, who most famously published a chronology that purported to establish the time and date of the creation according to the proleptic Julian calendar.

He wrote his most famous work, Annales veteris testamenti, a prima mundi origine deducti ("Annals of the Old Testament, deduced from the first origins of the world"), in 1650, and published its continuation, Annalium pars postierior, in 1654. In this work, he calculated the date of the Creation to have been nightfall preceding 23 October 4004 BC. (Other scholars, such John Lightfoot, calculated their own dates for the Creation.) The Ussher chronology is sometimes associated with Young Earth Creationism, which holds that the universe was created only a few millennia ago by God as described in the first two chapters of the biblical book of Genesis. In Ussher's time, such a calculation was regarded as a great accomplishment, one previously attempted by many Post-Reformation scholars, such as Joseph Justus Scaliger and physicist Isaac Newton. Ussher's contribution to the long-running theological debate on the age of the Earth had been a major concern of many Christian scholars over the centuries.

Linnaeaus -Justin

Carl Linnaeus (Swedish original name Carl Nilsson Linnæus, 23 May 1707 – 10 January 1778), was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology.

The Linnaean system classified nature within a nested hierarchy, starting with three kingdoms. Kingdoms were divided into classes and they, in turn, into orders, and thence into genera (singular: genus), which were divided into Species (singular: species). Below the rank of species he sometimes recognized taxa of a lower (unnamed) rank; these have since acquired standardised names such as variety in botany and subspecies in zoology. Modern taxonomy includes a rank of family between order and genus that was not present in Linnaeus' original system.

Although the system now known as binomial nomenclature was partially developed by the Bauhin brothers (see Gaspard Bauhin and Johann Bauhin) almost 200 years earlier, Linnaeus was the first to use it consistently and may be said to have popularised it within the scientific community.

In it, the unwieldy names mostly used at the time, such as "Physalis annua ramosissima, ramis angulosis glabris, foliis dentato-serratis", were supplemented with concise and now familiar "binomials", composed of the generic name, followed by a specific epithet – in the case given, Physalis angulata

While the underlying details concerning what are considered to be scientifically valid "observable characteristics" have changed with expanding knowledge (for example, DNA sequencing, unavailable in Linnaeus' time, has proven to be a tool of considerable utility for classifying living organisms and establishing their evolutionary relationships), the fundamental principle remains sound.

In 1959, Carl Linnaeus was designated as the lectotype for Homo sapiens, which means that following the nomenclatural rules, Homo sapiens was validly defined as the animal species to which Linnaeus belonged.

Major publications Systema Naturae(1735), Species Plantarum(1737) , Genera Plantarum (1737), Philosophia Botanica(1751)

Buffon - Craig

Georges Louis Leclerc, Comte of Buffon (French pronunciation: [ʒɔʁʒ lwi ləklɛʁ kɔ̃t də byfɔ̃]; 7 September 1707 – 16 April 1788) was a French naturalist, mathematician, cosmologist, and encyclopedic author. His works influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier. Buffon published thirty-six quartovolumes of his Histoire naturelle during his lifetime; with additional volumes based on his notes and further research being published in the two decades following his death.1 According to Ernst Mayer, “Truly, Buffon was the father of all thought in natural history in the second half of the 18th century".2 In the course of his examination of the animal world, Buffon noted that despite similar environments, different regions have distinct plants and animals, a concept later known as Buffon's Law. This is considered to be the first principle of biogeography. He made the suggestion that species may have both "improved" and "degenerated" after dispersing from a center of creation. In volume 14 he argued that all the world's quadrupeds had developed from an original set of just thirty-eight quadrupeds.3 On this basis, he is sometimes considered a "transformist" and a precursor of Darwin. He also asserted that climate change may have facilitated the worldwide spread of species from their centers of origin. Still, interpreting his ideas on the subject is not simple, for he returned to topics many times in the course of his work.

Buffon considered the similarities between humans and apes, but ultimately rejected the possibility of a common descent. He debated with James Burnett, Lord Monboddo on the relationship of the primates to man, Monboddo insisting, against Buffon, on a close relationship.4

The paradox of Buffon is that, according to Ernst Mayr: “He was not an evolutionist, yet he was the father of evolutionism. He was the first person to discuss a large number of evolutionary problems, problems that before Buffon had not been raised by anybody.... he brought them to the attention of the scientific world. Except for Aristotle and Darwin, no other student of organisms [whole animals and plants] has had as far-reaching an influence.”

Buffon brought the idea of evolution into the realm of science. He developed a concept of the "unity of type", a precursor of comparative anatomy. More than anyone else, Buffon was responsible for the acceptance of a long-time scale for the history of the earth. He was the founder of biogeography, and yet, he hindered evolution by his frequent endorsement of the immutability of species. Buffon provided a criterion of species, fertility among members of a species, that was thought impregnable.2

References:

1. Farber, Paul. (2000). Finding Order in Nature. Baltimore: Johns Hopkins University Press. pp. 14.

2. Mayr, Ernst. (1981). The Growth of Biological Thought. Cambridge: Harvard. pp. 330.

3. Roger, Jacques. (1989). Buffon: un philosophe au Jardin du Roi. Paris: Fayard. pp. 434–435.

4. Cloyd, E.L. (1972). James Burnett, Lord Monboddo. Oxford: Clarendon Press.

Lamarck - Ryan

Jean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck (1 August 1744 – 18 December 1829), often known simply as Lamarck, was a French naturalist. He was a soldier, biologist, academic, and an early proponent of the idea that evolution occurred and proceeded in accordance with natural laws. Lamarck developed a particular interest in botany. He published a three-volume work Flore françoise. In 1801, he published Système des animaux sans vertèbres, a major work on the classification of invertebrates, a term he coined. In an 1802 publication, he became one of the first to use the term biology in its modern sense.[3][Note 1] Lamarck continued his work as a premier authority on invertebrate zoology.

In the modern era, Lamarck is widely remembered for a theory of inheritance of acquired characteristics, called soft inheritance, Lamarckism or use/disuse theory.[4] However, his idea of soft inheritance was, perhaps, a reflection of the folk wisdom of the time, accepted by many natural historians. Lamarck's contribution to evolutionary theory consisted of the first truly cohesive theory of evolution,[5] in which an alchemical complexifying force drove organisms up a ladder of complexity, and a second environmental force adapted them to local environments through use and disuse of characteristics, differentiating them from other organisms.[6]

Lamarck stressed two main themes in his biological work. The first was that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle. The second principle was that life was structured in an orderly manner and that many different parts of all bodies make it possible for the organic movements of animals.[14] Although he was not the first thinker to advocate organic evolution, he was the first to develop a truly coherent evolutionary theory.[6] He outlined his theories regarding evolution first in his Floreal lecture of 1800, and then in three later published works: Recherches sur l'organisation des corps vivants, 1802. Philosophie Zoologique, 1809. Histoire naturelle des animaux sans vertèbres, (in seven volumes, 1815–1822). Lamarck employed several mechanisms as drivers of evolution, drawn from the common knowledge of his day and from his own belief in chemistry pre-Lavoisier. He used these mechanisms to explain the two forces he saw as comprising evolution; a force driving animals from simple to complex forms, and a force adapting animals to their local environments and differentiating them from each other. He believed that these forces must be explained as a necessary consequence of basic physical principles, favoring a materialistic attitude toward biology.

Cuvier - Jesse

Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier (sources differ on his name) (August 23, 1769 – May 13, 1832), known as Georges Cuvier, was a French naturalist and zoologist. Cuvier was a major figure in natural sciences research in the early 19th century, and was instrumental in establishing the fields of comparative anatomy and paleontology through his work in comparing living animals with fossils. He is well known for establishing extinction as a fact, being the most influential proponent of catastrophism in geology in the early 19th century, and opposing the evolutionary theories of Jean-Baptiste de Lamarck and Geoffroy Saint-Hilaire.

Cuvier was critical of the evolutionary theories proposed by his contemporaries Lamarck and Geoffroy Saint-Hilaire, which involved the gradual transmutation of one form into another. He repeatedly emphasized that his extensive experience with fossil material indicated that one fossil form does not, as a rule, gradually change into a succeeding, distinct fossil form. The harshness of his criticism and the strength of his reputation continued to discourage naturalists from speculating about the gradual transmutation of species, right up until Charles Darwin published On the Origin of Species more than two decades after Cuvier's death

At the time Cuvier presented his 1796 paper on living and fossil elephants, it was still widely believed that no species of animal had ever become extinct. Authorities such as Buffon had claimed that fossils found in Europe of animals such as the woolly rhinoceros and mammoth were remains of animals still living in the tropics (i.e. rhinoceros and elephants), which had shifted out of Europe and Asia as the earth became cooler. Cuvier's early work demonstrated conclusively that this was not the case.[25]

Malthus - Laura

The Reverend[1] Thomas Robert Malthus FRS (13 or 14 February 1766 – 23 or 29 December 1834[2]) was an English scholar, influential in political economy, demography, and scientific thought.[3][4] Malthus has become widely known for his theories about population and its increase or decrease in response to various factors. Many of those whom subsequent centuries term evolutionary biologists read him,[13] notably Charles Darwin and Alfred Russel Wallace, for each of whom Malthusianism became an intellectual stepping-stone to the idea of natural selection.[14][15]

Malthus placed the longer-term stability of the economy above short-term expediency. The six editions of his An Essay on the Principle of Population, published from 1798 to 1826, observed that sooner or later population gets checked by famine and disease.

“... the increase of population is necessarily limited by the means of subsistence, That population does invariably increase when the means of subsistence increase, and, That the superior power of population is repressed, and the actual population kept equal to the means of subsistence, by misery and vice.[9]”

Partly influenced by An Essay on the Principle of Population by Thomas Robert Malthus, Darwin noted that population growth would lead to a "struggle for existence" where favorable variations could prevail as others perished. Each generation, many offspring fail to survive to an age of reproduction because of limited resources. This could explain the diversity of animals and plants from a common ancestry through the working of natural laws working the same for all types of thing.[28][29][30][31]

Hutton - Justin

James Hutton FRSE (Edinburgh, 3 June 1726 OS (14 June 1726 NS) – 26 March 1797) was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. His work helped to establish the basis of modern geology. His theories of geology and geologic time, also called deep time, came to be included in theories which were called plutonism and uniformitarianism. He is also credited as the first scientist to publicly express the Earth was alive and should be considered a superorganism.

Hutton proposed that the interior of the Earth was hot, and that this heat was the engine which drove the creation of new rock: land was eroded by air and water and deposited as layers in the sea; heat then consolidated the sediment into stone, and uplifted it into new lands. This theory was dubbed "Plutonist" in contrast to the flood-oriented theory.

Rather than accepting that the earth was no more than a few thousand years old, he maintained that the Earth must be much older, with a history extending indefinitely into the distant past. His main line of argument was that the tremendous displacements and changes he was seeing did not happen in a short period of time by means of catastrophe, but that processes still happening on the Earth in the present day had caused them. As these processes were very gradual, the Earth needed to be ancient, in order to allow time for the changes. Before long, scientific inquiries provoked by his claims had pushed back the age of the earth into the millions of years – still too short when compared with the accepted 4.6 billion year age in the 21st century, but a distinct improvement.

Hutton also advocated uniformitarianism for living creatures too – evolution, in a sense – and even suggested natural selection as a possible mechanism affecting them: "...if an organised body is not in the situation and circumstances best adapted to its sustenance and propagation, then, in conceiving an indefinite variety among the individuals of that species, we must be assured, that, on the one hand, those which depart most from the best adapted constitution, will be the most liable to perish, while, on the other hand, those organised bodies, which most approach to the best constitution for the present circumstances, will be best adapted to continue, in preserving themselves and multiplying the individuals of their race." – Investigation of the Principles of Knowledge, volume 2.

Though he saw his "principle of variation" as explaining the development of varieties, Hutton rejected the idea of evolution originating species as a "romantic fantasy". As a deist, he thought the mechanism allowed species to form varieties better adapted to particular conditions and was evidence of benevolent design in nature.

Lyell - Craig

Sir Charles Lyell, 1st Baronet, Kt FRS (14 November 1797 – 22 February 1875) was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by the same processes still in operation today. Lyell was a close and influential friend of Charles Darwin. Lyell was one of the first scientists to support On the Origin of Species, though he did not subscribe to all its contents. Lyell was also a friend of Darwin's closest colleagues, Hooker and Huxley, but unlike them he struggled to square his religious beliefs with evolution. This inner struggle has been much commented on. He had particular difficulty in believing in natural selection as the main motive force in evolution. 1,2,3

Lyell and Joseph Dalton Hooker were instrumental in arranging the peaceful co-publication of the theory of natural selection by Darwin and Alfred Russel Wallace in 1858: each had arrived at the theory independently. Lyell's data on stratigraphy were important because Darwin thought that populations of an organism changed slowly, requiring "geologic time".

References:

1. Bowler, P.J. 2003). Evolution: the history of an idea. 3rd ed, University of California Press. ISBN 0-520-23693-9 pp. 129–134, 215.

2. Mayr, E. (1982). The growth of biological thought. Harvard University Press. ISBN 0-674-36446-5 pp. 375–381, 404–408.

3. Bartholomew, M. (1973). Lyell and evolution: an account of Lyell's response to the prospect of an evolutionary ancestry for man. Brit J Hist Sci 6 (3): 261–303.

Darwin - Ryan

What happened to my Darwin section?!!!?

Charles Robert Darwin, FRS (12 February 1809 – 19 April 1882) was an English naturalist. He established that all species of life have descended over time from common ancestors, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin published his theory with compelling evidence for evolution in his 1859 book On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species. By the 1870s the scientific community and much of the general public had accepted evolution as a fact. However, many favoured competing explanations and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life. Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. Studies at the University of Cambridge encouraged his passion for natural science. His five-year voyage on HMS Beagle established him as an eminent geologist whose observations and theories supported Charles Lyell's uniformitarian ideas, and publication of his journal of the voyage made him famous as a popular author. Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin began detailed investigations and in 1838 conceived his theory of natural selection. Although he discussed his ideas with several naturalists, he needed time for extensive research and his geological work had priority. He was writing up his theory in 1858 when Alfred Russel Wallace sent him an essay which described the same idea, prompting immediate joint publication of both of their theories. Darwin's work established evolutionary descent with modification as the dominant scientific explanation of diversification in nature. In 1871 he examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals. His research on plants was published in a series of books, and in his final book, he examined earthworms and their effect on soil.

Wallace - Jesse

Alfred Russel Wallace, (8 January 1823 – 7 November 1913) was a British naturalist, explorer, geographer, anthropologist and biologist. He is best known for independently proposing a theory of evolution due to natural selection that prompted Charles Darwin to publish his own theory.

Wallace was strongly attracted to unconventional ideas. His advocacy of Spiritualism and his belief in a non-material origin for the higher mental faculties of humans strained his relationship with the scientific establishment, especially with other early proponents of evolution.

Unlike Darwin, Wallace began his career as a travelling naturalist already believing in the transmutation of species. The concept had been advocated by Jean-Baptiste Lamarck, Geoffroy Saint-Hilaire, Erasmus Darwin, and Robert Grant, among others.

Wallace deliberately planned some of his field work to test the hypothesis that under an evolutionary scenario closely related species should inhabit neighbouring territories.[46] During his work in the Amazon basin, he came to realise that geographical barriers—such as the Amazon and its major tributaries—often separated the ranges of closely allied species.

In February 1855, while working in the state of Sarawak on the island of Borneo, Wallace wrote "On the Law which has Regulated the Introduction of New Species". In this paper, he discussed observations regarding the geographic and geologic distribution of both living and fossil species, what would become known as biogeography. His conclusion that "Every species has come into existence coincident both in space and time with a closely allied species" has come to be known as the "Sarawak Law".

Wallace trusted Darwin's opinion on the matter and sent him his February 1858 essay, "On the Tendency of Varieties to Depart Indefinitely From the Original Type", with the request that Darwin would review it and pass it on to Charles Lyell if he thought it worthwhile

While Wallace's essay did not employ Darwin's term "natural selection", it did outline the mechanics of an evolutionary divergence of species from similar ones due to environmental pressures. Darwin emphasised competition between individuals of the same species to survive and reproduce, whereas Wallace emphasised environmental pressures on varieties and species forcing them to become adapted to their local environment.

After the publication of Darwin’s On the Origin of Species, Wallace became one of its staunchest defenders.

In many accounts of the development of evolutionary theory, Wallace is mentioned only in passing as simply being the stimulus to the publication of Darwin's own theory.[96] In reality, Wallace developed his own distinct evolutionary views which diverged from Darwin's, and was considered by many (especially Darwin) to be a leading thinker on evolution in his day, whose ideas could not be ignored

Huxely - Justin

Thomas Henry Huxley PC FRS (4 May 1825 – 29 June 1895) was an English biologist (anatomist), known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution.

Huxley's detailed anatomical work was first-rate and productive. His work on fossil fish shows his distinctive approach: whereas pre-Darwinian naturalists collected, identified and classified, Huxley worked mainly to reveal the evolutionary relationships between groups.

The tendency has been for this fine anatomical work to be overshadowed by his energetic and controversial activity in favour of evolution, and by his extensive public work on scientific education, both of which had significant effects on society in Britain and elsewhere.

Huxley was originally not persuaded of 'development theory' as evolution was once called. Huxley's reservations on natural selection were of the type "until selection and breeding can be seen to give rise to varieties which are infertile with each other, natural selection cannot be proved". Huxley's position on selection was agnostic; yet he gave no credence to any other theory.

The publication of Charles Darwin's The Origin of Species in 1859 completely convinced Huxley of evolution and it was this and no doubt his admiration of Darwin's way of amassing and using evidence that formed the basis of his support for Darwin in the debates that followed the book's publication. "I am Darwin's bulldog" said Huxley, and it is apt; the second half of Darwin's life was lived mainly within his family, and the younger, combative Huxley operated mainly out in the world at large.

He was the leading person amongst those who reformed the Royal Society, persuaded government about science, and established scientific education in British schools and universities. Before him, science was mostly a gentleman's occupation; after him, science was a profession.

In 1869 Huxley coined the term 'agnostic' to describe his own views on theology, a term whose use has continued to the present day.

Pastuer - Laura

Louis Pasteur ( /ˈluːi pæˈstɜr/, French: [lwi pastœʁ]; December 27, 1822 – September 28, 1895) was a French chemist and microbiologist who was one of the most important founders of medical microbiology. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases, and is credited with developing pasteurization and the law of biogenesis. The law of biogenesis is the observation that living things come only from other living things, by reproduction (e.g. a spider lays eggs, which develop into spiders). In 1864, Pasteur demonstrated through a series of experiments that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is not due to spontaneous generation,[2] but rather to biogenesis (Omne vivum ex vivo- "all life is from life"). Pasteur's results showing that life does not arise from non-living material was influential in changing a widely accepted biological paradigm of the time.

Mendel - Justin

Gregor Johann Mendel (July 20, 1822 – January 6, 1884) was a scientist and Augustinian friar who gained posthumous fame as the founder of the new science of genetics. Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance. Although the significance of Mendel's work was not recognized until the turn of the 20th century, the independent rediscovery of these laws formed the foundation of the modern science of genetics.

Between 1856 and 1863 Mendel cultivated and tested some 29,000 pea plants (i.e., Pisum sativum). This study showed that one in four pea plants had purebred recessive alleles, two out of four were hybrid and one out of four were purebred dominant. His experiments led him to make two generalizations, the Law of Segregation and the Law of Independent Assortment, which later became known as Mendel's Laws of Inheritance.

Mendel's work was rejected at first, and was not widely accepted until after he died. During his own lifetime, most biologists held the idea that all characteristics were passed to the next generation through blending inheritance, in which the traits from each parent are averaged together. Instances of this phenomenon are now explained by the action of multiple genes with quantitative effects. Charles Darwin tried unsuccessfully to explain inheritance through a theory of pangenesis. It was not until the early 20th century that the importance of Mendel's ideas was realized.

The combination, in the 1930s and 1940s, of Mendelian genetics with Darwin's theory of natural selection resulted in the modern synthesis of evolutionary biology.

Modern Synthesis

Weismann - Laura

Friedrich Leopold August Weismann (17 January 1834 – 5 November 1914) was a German evolutionary biologist.[1] His major contribution was the germ plasm theory, according to which (in a multicellular organism) inheritance only takes place by means of the germ cells—the gametes such as egg cells and sperm cells. Other cells of the body—somatic cells—do not function as agents of heredity. The Weismann barrier, a term referring to the inability of genetic information to pass from soma to germ plasm and on to the next generation, refutes the inheritance of acquired characteristics as proposed by Jean-Baptiste Lamarck. The idea of the Weismann barrier is central to the Modern evolutionary synthesis, though it is not expressed today in the same terms.

Weismann was one of the first biologists to deny such ideas as Lamarckism, that an organism can pass on characteristics that it acquired during its lifetime to its offspring. By 1883, Weismann viewed the largely random process of mutation, which must occur in the gametes (or stem cells that make them), as the only source of change on which natural selection can work. [4] The idea that germ cells are not influenced by environmental influences, learning, or morphological changes that happen during the lifetime of an organism was illuminated and explained by the rediscovery of Gregor Mendel's work in the early years of the 20th century.

In a famous experiment, Weismann removed the tails of 68 white mice over 5 generations. He reported no mice subsequently born without tails or shortened tails. Weismann performed the experiment in response to many claims of animals inheriting mutilations, including claims of Jews born without foreskins. None of these claims, Weismann concluded, were reliably supported by evidence of mutilation inflicted on the parent, leaving the possibility that the modified offspring were the result of a mutated gene. These results were also consistent with germ plasm theory.

Beyond germ plasm theory, Weismann can be credited with the insight that two cell divisions are necessary to transform one diploid cell into four haploid cells in order to maintain the number of chromosomes. Additionally, he wrote extensively on creationism and evolutionary theory, concluding that many biological facts can be seamlessly accommodated within evolutionary theory, but remain puzzling if considered the result of acts of creation.

De Vries - Jesse

Hugo Marie de Vries (February 16, 1848, Haarlem – May 21, 1935, Lunteren) was a Dutch botanist and one of the first geneticists. He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation theory of evolution.

In 1889, De Vries published his book Intracellular Pangenesis,[4] in which, based on a modified version of Charles Darwin's theory of Pangenesis of 1868, he postulated that different characters have different hereditary carriers. He specifically postulated that inheritance of specific traits in organisms comes in particles. He called these units pangenes, a term 20 years later to be shortened to genes by Wilhelm Johannsen.

To support his theory of pangenes, which was not widely noticed at the time, De Vries conducted a series of experiments hybridising varieties of multiple plant species in the 1890s. Unaware of Mendel's work, De Vries used the laws of dominance and recessiveness, segregation, and independent assortment to explain the 3:1 ratio of phenotypes in the second generation

In his own time, De Vries was best known for his mutation theory. In 1886 he had discovered new forms among a display of the evening primrose (Oenothera lamarckiana) growing wild in a meadow. Taking seeds from these, he found that they produced many new varieties in his experimental gardens; he introduced the term mutations for these suddenly appearing variations. In his two-volume publication The Mutation Theory (1900–1903) he postulated that evolution, especially the origin of species, might occur more frequently with such large-scale changes than via Darwinian gradualism, basically suggesting a form of saltationism. De Vries's theory was one of the chief contenders for the explanation of how evolution worked, leading, for example,Thomas Hunt Morgan to study mutations in the fruit fly, until the modern evolutionary synthesis became the dominant model in the 1930s

Fisher - Craig

Sir Ronald Aylmer Fisher FRS (17 February 1890 – 29 July 1962) was an English statistician, evolutionary biologist, eugenicist and geneticist. Among other things, Fisher is well known for his contributions to statistics by creating Fisher's exact test and Fisher's equation. Anders Hald called him "a genius who almost single-handedly created the foundations for modern statistical science"1 while Richard Dawkins named him "the greatest biologist since Darwin".2

Fisher’s work on the theory of population genetics made him one of the three great figures of that field, together with Sewall Wright and J.B.S. Haldane, and as such was one of the founders of the neo-Darwinian modern evolutionary synthesis. In addition to founding modern quantitative genetics with his 1918 paper, he was the first to use diffusion equations to attempt to calculate the distribution of gene frequencies among populations. He pioneered the estimation of genetic linkage and gene frequencies by maximum likelihood methods, and wrote early papers on the wave of advance of advantageous genes and on clines of gene frequency. His 1950 paper, Gene Frequencies in a Cline Determined by Selection and Diffusion, is notable as the first application of a computer, the EDSAC, to biology. Fisher had a long and successful collaboration with E.B. Ford in the field of ecological genetics. The outcome of this work was the general recognition that the force of natural selection was often much stronger than had been appreciated before, and that many ecogenetic situations (such as polymorphism) were not selectively neutral, but were maintained by the force of selection. Fisher was the original author of the idea of heterozygote advantage, which was later found to play a frequent role in genetic polymorphism.3 The discovery of indisputable cases of natural selection in nature was one of the main strands in the modern evolutionary synthesis.

References:

1. Hald, Anders. (1998). A History of Mathematical Statistics. New York: Wiley. ISBN 0-471-17912-4.

2. Dawkins, R. (2010). WHO IS THE GREATEST BIOLOGIST SINCE DARWIN? WHY? Edge.

3. Fisher R. 1930. The Genetical Theory of Natural Selection.

Haldane - Ryan

John Burdon Sanderson Haldane FRS (5 November 1892 – 1 December 1964[1]), known as Jack (but who used 'J.B.S.' in his printed works), was a British-born geneticist and evolutionary biologist generally credited with a central role in the development of neo-Darwinian thinking. He was also one of the founders (along with Ronald Fisher and Sewall Wright) of population genetics. Haldane made many contributions to human genetics. His greatest contribution was in a series of ten papers on "A Mathematical Theory of Natural and Artificial Selection", which was a major series of papers on the mathematical theory of natural selection. It treated many major cases for the first time, showing the direction and rates of changes of gene frequencies. It also pioneered in investigating the interaction of natural selection with mutation and with migration. Haldane's book, The Causes of Evolution (1932) was a component of what came to be known as the "modern evolutionary synthesis", re-establishing natural selection as the premier mechanism of evolution by explaining it in terms of the mathematical consequences of Mendelian genetics. His contributions to theoretical population genetics and statistical human genetics included the first methods using maximum likelihood for estimation of human linkage maps, and pioneering methods for estimating human mutation rates. His was the first to calculate the mutational load caused by recurring mutations at a gene locus, and to introduce the idea of a "cost of natural selection".

He is famous for the (possibly apocryphal) response that he gave when some theologians asked him what could be inferred about the mind of the Creator from the works of His Creation: "An inordinate fondness for beetles."[12] This is in reference to there being over 400,000 known species of beetles in the world, and that this represents 40% of all known insect species (at the time of the statement, it was over half of all known insect species)

Wright - Jesse

Sewall Green Wright (December 21, 1889 – March 3, 1988) was an American geneticist known for his influential work on evolutionary theory. With R. A. Fisher and J.B.S. Haldane, he was a founder of theoretical population genetics. He is the discoverer of the inbreeding coefficient and of methods of computing it in pedigrees. He extended this work to populations, computing the amount of inbreeding of members of populations as a result of random genetic drift, and he and Fisher pioneered methods for computing the distribution of gene frequencies among populations as a result of the interaction of natural selection, mutation, migration and genetic drift.

His papers on inbreeding, mating systems, and genetic drift make him a principal founder of theoretical population genetics. Wright was the inventor/discoverer of the inbreeding coefficient and F-statistics, standard tools in population genetics. He was the chief developer of the mathematical theory of genetic drift, which is sometimes known as the Sewall Wright effect, cumulative stochastic changes in gene frequencies that arise from random births, deaths, and Mendelian segregations in reproduction. In this work he also introduced the concept of effective population size. Wright was convinced that the interaction of genetic drift and the other evolutionary forces was important in the process of adaptation.

He described the relationship between genotype or phenotype and fitness as fitness surfaces or fitness landscapes. On these landscapes mean population fitness was the height, plotted against horizontal axes representing the allele frequencies or the average phenotypes of the population. Natural selection would lead to a population climbing the nearest peak, while genetic drift would cause random wandering.

Wright's explanation for stasis was that organisms come to occupy adaptive peaks. In order to evolve to another, higher peak, the species would first have to pass through a valley of maladaptive intermediate stages. This could happen by genetic drift if the population is small enough. If a species was divided into small populations, some could find higher peaks. If there was some gene flow between the populations, these adaptations could spread to the rest of the species. This was Wright's shifting balance theory of evolution. There has been much skepticism among evolutionary biologists as to whether these rather delicate conditions hold often in natural populations. Wright had a long standing and bitter debate about this with R. A. Fisher, who felt that most populations in nature were too large for these effects of genetic drift to be important.

Wright and Fisher, along with J.B.S. Haldane, were the key figures in the modern synthesis that brought genetics and evolution together. Their work was essential to the contributions of Dobzhansky, Mayr, Simpson, Julian Huxley, and Stebbins. The modern synthesis was the most important development in evolutionary biology after Darwin.

Stebbins - Laura

George Ledyard Stebbins, Jr. (January 6, 1906 – January 19, 2000) was an American botanist and geneticist who is widely regarded as one of the leading evolutionary biologists of the 20th century. His work on the genetic evolution of plant species and association with other influential evolutionary biologists led him to develop a comprehensive synthesis of plant evolution incorporating genetics.

Stebbins’ most important publication was Variation and Evolution in Plants. Published in 1950, the work combined genetics and Darwin's theory of natural selection to describe plant speciation. It is regarded as one of the main publications which formed the core of the modern evolutionary synthesis and still provides the conceptual framework for research in plant evolutionary biology. In the book, Stebbins argued that evolution needed to be studied as a dynamic problem and that must be considered on three levels: first, that of individual variation within an interbreeding population; second, that of the distribution and frequency of this variation; and third, that of the separation and divergence of populations as the result of the building up of isolating mechanisms leading to the formation of species.[13] He also demonstrated that it was possible to distinguish between genotypic and phenotypic variation—that is, genetically identical plants could have different phenotypes in different environments. One of the book's most original chapters showed that genetic systems like hybridization and polyploidy were also subject to selection.

Additionally, Stebbins researched and wrote extensively on the role of hybridization and polyploidy in speciation and plant evolution. Together with E.B. Babcock, Stebbins described the concept of the polyploid complex and its role in plant evolution. Based on observation and experimentation, they proposed that polyploids formed through hybridization have a greater potential to exploit varied environments, because they inherit all traits from both parents. They also showed that hybridization in the polyploid complex could provide a mechanism for genetic exchange between diploid species that were otherwise unable to breed. Their observations offered insight into species formation and knowledge of how all these complex processes could provide information on the history of a genus.

In 1954, Stebbins continued his work on the importance of hybridization in plant adaptation to new environments with Edgar Anderson. They proposed novel adaptations would facilitate the invasion of habitats not utilized previously by either parent and that novel adaptations may facilitate the formation of stabilized hybrid species.[18]Following this paper, Stebbins developed the first model of adaptive radiation.[19][20] He proposed that a high degree of genetic variability was necessary for major evolutionary advances, that because of slow mutation rates, genetic recombination was the most likely source of this variation, and that variation could be maximized through hybridization. As of 2006, research is ongoing regarding whether hybridization is an accidental consequence of evolution or if it is necessary for the creation and evolution of plant species;[21] it has been argued that contemporary studies are part of an intellectual lineage that started with the work of Stebbins and Anderson. Dobzhansky - Justin

Theodosius Grygorovych Dobzhansky ForMemRS (Ukrainian: Теодосій Григорович Добжанський; January 24, 1900 - December 18, 1975) was a prominent geneticist and evolutionary biologist, and a central figure in the field of evolutionary biology for his work in shaping the unifying modern evolutionary synthesis.

Through his work on Drosophila pseudoobscura he was able to identify that some populations of this species did not have identical sets of genes. Dobzhansky used experimental breeding in laboratories and gardens, and also surveys related to species in nature to help support the aspects of organic evolution.

In 1937, he published one of the major works of the modern evolutionary synthesis, the synthesis of evolutionary biology with genetics, entitled Genetics and the Origin of Species, which amongst other things, defined evolution as "a change in the frequency of an allele within a gene pool". The book popularized the work of population genetics to other biologists, and influenced their appreciation for the genetic basis of evolution. Dobzhansky's work was instrumental in spreading the idea that it is through mutations in genes that natural selection takes place.

Mayr - Craig

Ernst Walter Mayr (July 5, 1904 – February 3, 2005)1 was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, and historian of science.2 His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.

Neither Charles Darwin nor anyone else in his time knew the answer to the species problem: how multiple species could evolve from a single common ancestor. Ernst Mayr approached the problem with a new definition for the concept of species. In his book Systematics and the Origin of Species (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become isolated by geography, feeding strategy, mate selection, or other means, they may start to differ from other populations through genetic drift and natural selection, and over time may evolve into new species. The most significant and rapid genetic reorganization occurs in extremely small populations that have been isolated (as on islands).

His theory of peripatric speciation (a more precise form of allopatric speciation which he advanced), based on his work on birds, is still considered a leading mode of speciation, and was the theoretical underpinning for the theory of punctuated equilibrium, proposed by Niles Eldredge and Stephen Jay Gould. Mayr is sometimes credited with inventing modern philosophy of biology, particularly the part related to evolutionary biology, which he distinguished from physics due to its introduction of (natural) history into science.

References:

1. Meyer, A. (2005). On the Importance of Being Ernst Mayr. PLoS Biology 3(5): e152. doi:10.1371/journal.pbio.0030152.

2. Rennie, J. (1994). Profile: Ernst Mayr – Darwin's Current Bulldog. Scientific American. 271(2), pp. 24-25.

Simpson - Ryan

George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern evolutionary synthesis, contributing Tempo and mode in evolution (1944), The meaning of evolution (1949) and The major features of evolution (1953).

Simpson's Tempo and Mode attempted to draw out several distinct generalizations: That evolution's tempo can impart information about its mode. That multiple tempos can be found in the fossil record (bradytelic, tachytelic, horotelic). That the facts of paleontology are consistent with the genetical theory of natural selection. Moreover, that theories such as orthogenesis, Lamarckism, mutation pressures, and macromutations are either false or play little to no role. Most evolution—"nine-tenths"—occurs by the steady phyletic transformation of whole lineages (anagenesis). In contrast to Ernst Mayr's interpretation of speciation by splitting, particularly allopatric and peripatric speciation. The lack of evidence for evolutionary transitions in the fossil record is best accounted for, first, by the poorness of the geological record, and secondly as a consequence of quantum evolution (which is responsible for "the origin taxonomic units of relatively high rank, such as families, orders, and classes."). Quantum evolution built upon Sewall Wright's theory of random genetic drift.