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Human Evolution

Human Evolution. Also Known As… Please stop saying “We descended from chimps” or apes for that matter, because it is not true and if you write it on your test it’s only gonna get you a zero genius!. Leaving the Others Behind.

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Human Evolution

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  1. Human Evolution Also Known As… Please stop saying “We descended from chimps” or apes for that matter, because it is not true and if you write it on your test it’s only gonna get you a zero genius!

  2. Leaving the Others Behind • Humans did not evolve from chimps or apes – please make note of this right now! • The human ancestral lineage separated from the other mammals based on several characteristics that emerged around 60 million years ago… • Flattened molars for plant based diet. • Grasping hands and feet - hooray for the opposable thumb…Ask your dog to get the door for you and watch him suffer in silence. • Forward-directed eyes for binocular vision and better depth perception.

  3. Primate Phylogeny • Remember…we started becoming “human” about 60 million years ago. • Over the next 20-30 million years, a divergence occurred and the prosimian and anthropoid lineages arose. • Prosimian – Are now present-day lemurs and such. Characterized by very large eyes, a long tail and nocturnal activities. • Anthropoid – Are now present-day monkeys, apes and humans. Characterized by large brains, enhanced senses and social groupings.

  4. These are not the Anthropoids You’re Looking For! • The anthropoid lineage split about 25-30 million years ago into the Old World Monkeys, the New World Monkeys and the Hominoid lineage. • Old World Monkeys – Tree and ground dwelling species. Nostrils close together and tails that can not grasp things. • New World Monkeys – Exclusively in trees, widely flared nostrils and tails can grasp items. • Hominoids – Humans, chimps & apes (including the now extinct members of this clade).

  5. The Emergence of Humans • Humans evolved from an “ape-like” ancestor. This means we used to be like the apes – we did not evolve from the apes you see at the zoo – leave them out of this! • Humans form the hominid lineage. The beginning of this lineage began at the divergence of the ape-like ancestor – one side went human and the other went ape!

  6. Emergence of Humans • The current fossil record indicates the hominid clade has a wide degree of variety and many branching lineages. • Ardipithecus ramidus – about 5.2 to 5.8 million years ago. • Australopithecus – several species ranging back from 4.2 to 1.0 million years ago. • The Australopithecene line would have included A. afarensis and A. africanus who both walked on their knuckles. The move to being a bipedal and the increase in brain size would have eventually saw the rise of the Homo lineages.

  7. The Emergence of Homos! • Don’t laugh…we are the “homos” in question here. • The oldest Homo fossils date back to 2.4 to 1.6 million years ago. The earliest of these was Homo habilis whose features mirrored that of man more than ape. Stone tools were also thought to be introduced by H. habilis. • Homo erectus arose about 1.6 million years ago. Homo erectus also used tools and fire and had an even more pronounced human look about him. Scientists believe that they originated in Africa and spread to Europe and Asia. • Homo erectus is believed to have given rise to Homo neanderthalensis and Homo sapiens. Homo neanderthalensis is thought to have made complex tools, had burial ceremonies and made use of complex language.

  8. Where Did We Come From? • There are two competing theories that describe the most recent chapter of human evolution – the multiregional hypothesis and the monogenesis hypothesis. • Multiregional hypothesis – humans evolved in a number of locations including Africa, Europe, Asia and possibly Australia. • The differences in populations are thought to be in response to different selection pressures exerted by each environment. • Gene flow between neighboring populations would have occurred since they all remained within the same species.

  9. Out of Africa • Monogenesis hypothesis – proposes that Homo sapiens evolved only in Africa and then migrated to the other locations, displacing Neanderthal species along the way. • See figure 10 on page 620. • Molecular evidence (including the Human genome Project) favors the monogenesis hypothesis. In terms of genetic variation, there exists much more in Africa indicating it to be an older population than in other regions of the world. • Remember…we said that the greater the number of genetic differences there are the further back the split in the species. • Monogenesis receives more support from the scientific community.

  10. Just One More Reminder… • We evolved from a similar ancestor to the apes and chimps – we did not evolve from apes or chimps. • I will absolutely snap if you say, “Hey MacDonald, we evolved from chimps or apes.” • Instant zero for you Einstein! • Go ahead try it – I know places they’ll never find you…You will be part of the fossil record!

  11. FIN

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