2011-24_Huma - EVOLUTION (11:704-486) HUMAN EVOLUTION...

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EVOLUTION (11:704-486) HUMAN EVOLUTION SMOUSE SPRING - 2011 1 H UMAN E VOLUTION Phylogenetic Relationships: Let me start our discussion of human evolution with the observation that although Darwin had little to say about the subject in his Origin of Species , it had already become obvious that if humans had taxonomic relatives, they were to be found among the great apes. The taxonomy that followed had humans as a separate family: Great Apes include the Orangutan, the Gorilla, the Chimp, and this was thought to be the closest family to humans. The gibbon was placed in its own family, as was the human lineage. For a long time, it got left that way, but even Linnaeus had his doubts, which he expressed privately, in letters to friends. Prosim NWM OWM Gi O Go C H With modern molecular evidence, and a better understanding of the anatomical details for these various species, it now seems far more likely that humans should be grouped with Gorillas and Chimpanzees, a tad closer to the latter, with the Orangutan in another family. If we ignore all the other taxa, we have something more like: Gi O Go C B H The gibbon is in one family, Hylobatideae, all the others in a single family, Hominidae, with the orang in one subfamily (Ponginae), and with the gorilla, common chimp and pygmy chimp (Bonobo) and humans in another (Homoninae). Gorilla, chimps and humans are placed in three different genera. Voluminous evidence now places humans closest to chimps. The Fossil Record – If you look at the fossil record for the great apes and humans, it seems to go back about 6 Mya, when the Gorilla lineage split off from what was then the chimp-human lineage. About 4.6-5.0 Mya, hominids split off from chimps, as nearly as we can tell. It has to Note addition of the Bonobo (pygmy chimp), which Linneaus did not know about, but which we now do.
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EVOLUTION (11:704-486) HUMAN EVOLUTION SMOUSE SPRING - 2011 2 be said that the ancestor of chimps and humans was probably more like chimps and gorillas, since many of the ancestral characters for the great apes are retained in both species. We don’t really seem to have a decent fossil record for chimps or gorillas, both of which live in tropical rainforest, which – as I pointed out, is not ideal habitat for preserving fossils. Still, I suspect we have been looking a lot harder for the human ancestors than for the great ape ancestors. They may yet turn up, once we start looking a little harder. The earliest fossil hominids are classified as Australopithecus ( southern ape man ), dating to about 4.4 Mya. There have been a whole series of finds, showing that different features developed at different rates. Australopithecus was already bipedal, but still had long arms & was a climber, as are chimps today. I’ll just give you the series, as a figure from
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2011-24_Huma - EVOLUTION (11:704-486) HUMAN EVOLUTION...

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