Wikipedia:Reference desk/Archives/Science/2022 May 21

= May 21 =

Chain of human ancestors
Beginning with modern humans and walking backwards, how close-grained do we know the chain of all our ancestors? It's modern humans <<< homo erectus (?) <<< what are the known links here? <<< LUCA? --Bumptump (talk) 17:53, 21 May 2022 (UTC)
 * The farther you go back, the harder it is to ascertain that a fossil find is part of the chain of species, and not a node on a nearby side branch. The main reason is the increasing sparsity of the fossil record and the very incomplete preservation of ancient finds, making it often very uncertain whether two specimens are co-specifics or merely close relatives. The best scientists have been able to do can be found pieced together in Timeline of human evolution. Using the assumption that the average life span of a species (from emergence to extinction) is 5–10 My and that multicellular life has existed for 600 My, there should be some 80 nodes on the multicellular part of the chain. Not only does it fall far short of that, but most nodes do not indicate a concrete species, but rather the emergence of a clade. I don’t know if even Homo erectus can be identified with reasonable certainty as an ancestor species of Homo sapiens. --Lambiam 18:47, 21 May 2022 (UTC)
 * Our article on Homo is also pretty detailed in this respect. Shantavira|feed me 18:49, 21 May 2022 (UTC)
 * The Homo article does not go back further than 20.4 My. That leaves a gap of some 3 to 4 billion years to LUCA. --Lambiam 04:27, 22 May 2022 (UTC)
 * There's going to be variation in populations too, you might find Homo Neanderthalis ancestry in some people, Homo Floresiensis in others etc... It's fringe afaik but it's reckoned some of the Paracas (i think, maybe later Nazca) people could have descended from another Homo species with non-artificially elongated heads that were a higher caste if you will so people in later generations bound their children's heads in order to mirror the appearance of those high status people Zindor (talk) 19:55, 21 May 2022 (UTC)
 * I can strongly recommend The Ancestor's Tale by by Richard Dawkins and Yan Wong. It cover exactly this question. —  Wasell ( T ) 🌻 09:27, 23 May 2022 (UTC)