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NIS - BIOLOGY

NIS - BIOLOGY. Lecture 76 – Lecture 77 – Lecture 78 Human Ancestry Ozgur Unal. Have you ever heard anyone use the term “cave man” in an insulting way? Why would it be insulting?. The Genus Homo. The people who lived in caves 40,000 years ago were much like modern humans.

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NIS - BIOLOGY

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  1. NIS - BIOLOGY Lecture 76 – Lecture 77 – Lecture 78 Human Ancestry OzgurUnal

  2. Have you ever heard anyone use the term “cave man” in an insulting way? • Why would it be insulting? The Genus Homo • The people who lived in caves 40,000 years ago were much like modern humans. • Their art was beautiful and their tools were sophisticated.

  3. The African environment became considerably cooler between 3 and 2.5 mya. • Forests became smaller in size and the range of grasslands was extended. • The genus Homo, which includes living and extinct humans, first appeared during these years. • Although the fossil record is lacking fossils, many scientists infer that they evolved from an ancestor of the australopithecines. The Genus Homo • Homo species had bigger brains, lighter skeletons, flatter faces and smaller teeth. • They are also the first species known to control fire and to modify stones for tool use. • As they evolved, they developed language and culture.

  4. The earliest Homo species  Homo habilis • (2.4 – 1.4 mya) • Aka “handy man”, because of its association with primitive stone tools. • Check out Figure 16.17!! Homo habilis • H. Habilis possessed a brain averaging 650 cm3  20 % larger than that of the australopithecines • Homo species traits  smaller brow, reduced • jaw, flatter face, humanlike teeth • Austrlopithecines species traits  longer armed, • small

  5. Within about 500,000 years of appearance of H. Habilis, another homo species emerged with a larger brain. • H. Ergaster appeared only briefly in the fossil record (1.8 – 1.3 mya) • Taller and lighter than H habilis • Longer legs and shorter arms • 1000 cm3  average brain size • Rounded skull, reduced teeth • First human nose • They used carefully made hand axes • and other tools. • H. Ergaster appears to have been the first • African Homo species to migrate in large • numbers to Asia and possible Europe. Homo ergaster

  6. Homo erectus lived between 1.8 – 0.4 mya. • They appear to have evolved from H ergaster as it migrated out of Africa. • They adapted successfully to a variety of environments. • Famous fossil examples: Java man (1890s) and Peking man (1926) Homo erectus • In general, H erectus was larger than H habilis. • Larger brain (900 cm3 – 1100 cm3) • More humanlike teeth • As tall as H sapiens • But longer skull, lower forehead and thicker facial bones than H ergaster and H sapiens • Prominent browridge • H erectus used sophisticated tools, used fire and sometimes lived in caves.

  7. Homo erectus

  8. Most scientists believe that H erectus went extinct about 0.4 mya. • However, a set of fossils found in 2004 in Flores (Indonesia) suggest that descendants of H erectus remained on Earth until 12,000 years ago. • These fossils (18,000 years old) represent a species called Homo floresiensis  aka The Hobbit • Only 1 m tall when full grown • Check out Figure 16.20!! Homo floresiensis

  9. The transition from H ergaster to modern humans appears to have occured gradually. • Numerous transitional fossils have been found that display a mxiture or mosaic of H ergaster and H sapiens traits. • These fossils are often categorized as Homo heidelbergensis. • These humans generally had larger brains and thinner boned than H ergaster. • But they still had browridges • and receding chins. Homo heidelbergensis

  10. A distinct human species – Homo neanderthalensis (Neanderthals) – evolved exclusively in Europe and Asia about 200,000 years ago, likely from H erectus or a Homo intermedietary. • Neanderthals were shorter but had more muscle mass than most modern humans. • Their brains were sometimes even larger than the brains of modern humans. • They had thick skulls, bony browridges and large noses. • There is evidence that they used fire and • constructed complex shelters. • They hunted and skinned animals. • They possibly had basic language. • They cared for their sick and buried their dead. Homo neanderthalensis

  11. Neanderthals and humans overlapped in some regions for about 10,000 years. • Some scientists suggest that the two species interbred. • However, DNA tests on fossil bones suggest that Neanderthals were a distinct species that did not contribute to the modern human gene pool. • Neanderthals went extinct about 30,000 years ago. • The reasons why they went extinct are • not known. Homo neanderthalensis

  12. The species that displaced the Neanderthals  Homo sapiens • Characterized by a more slender appearance than all other Homo species • Thinner skeletons, rounder skulls and smaller faces with prominent chins • Brain capacity  1350 cm3 • Check out Table 16.2!! Emergence of Modern Humans • First appeared in the fossil record about 195,000 • years ago in Ethiopia • These early H sapiens made chipped hand axes • and other sophisticated stone tools. • At some point they began migrating out of Africa.

  13. Check out Figure 16.22!! • About 0.2 mya, which homo species coexisted? • Which homo species remain on Earth today? Emergence of Modern Humans • Some scientists suggest convergent evolution for different races of humans today  Multiregional evolution model • Most scientists explain the global dominance of modern humans with the African Replacement model  Out-of-Africa hypothesis • According to this hypothesis, • modern humans evolved only • once, in Africa, and then • migrated to all parts of the • world, eventually displacing • other hominins.

  14. The out-of-Africa hypothesis is supported by mitochondrial DNA analysis of contemporary humans in the early 1990s. • Mitochondrial DNA changes very little over time and humans living today have nearly identical mitochondrial DNA. • The population with the most variation should be the population that has had the longest time to accumulate • diversity. • This was found in the • mitochondrial DNA of Africans. • Because mitochondrial DNA is • inherited only from the mother, • this analysis suggested that • H sapiens emerged in Africa about • 200,000 years ago from a • hypothetical “Mitochondrial Eve”. Emergence of Modern Humans

  15. Later work by other scientists studying DNA sequences in the male Y chromosome yielded similar results. • While some scientists think that a single movement of only a few hundred modern humans ultimately gave rise to the world’s current population, • ....others think the process • occured in phases, with some • interbreeding among the • species that humans displaced. Emergence of Modern Humans

  16. The first evidence of complex human culture appeared in Europe only about 40,000 years ago  Shortly before the Neanderthals disappeared • Check out Figure 16.23!! • They developed sophisticated tools and weapons, including spears and bows and arrows. • They were the first to fish, the first to tailor clothing and first to domesticate animals. • Some people call these fully modern humans Cro-Magnons. • They represent the beginning of historic • hunter-gatherer societies. • How do you think these early modern humans • spread to all continents in the world? Emergence of Modern Humans

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