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Published byMarsha Caldwell Modified over 8 years ago
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Hominid Evolution
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Physical features that define humans as primates: grasping limbs with opposable thumb strong mobile arms/shoulders stereoscopic vision on flattened face skull modified for upright posture
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Correlation between change in hominid diet and increase in brain size in well under 3 million years the brain tripled in size and evolved a cortex that accounts for a staggering 70 to 80 per cent of brain volume among living primates, the relative proportion of metabolic energy allocated to the brain is positively correlated with dietary quality. scavenging and hunting coincided with the emergence of the genus Homo. unlike their robust Australopithecine cousins, they scavenged meat and they used stone tools to do so. Scavenging and hunting capacitated survival in ecologies without the ancestral plants of the African tropics. H. habilis was certainly a scavenger, and possibly a hunter. Eating meat enabled a significant dispersal in more northerly latitudes and into new ecological niches. the first hominid tools provided a technology that added a first stage to digestion, preprocessing foods and giving early hominids access to a wider range of nutritional resources, imparting a survival advantage
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Early human-like fossils – there are many gaps in the hominid fossil record and it is far from clear how humans evolved. The Australopithecine Line (4.5 – 1mya) 1-1.5m tall walked upright human like teeth possibly hunted with weapons cranial capacity of 450-650cc
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Species: –Australopithecus afarensis: 4-2.5 mya, Southern or Eastern Africa. “Lucy” –A. africanus: 3-2.5 mya, Southern or Eastern Africa –A. robustus: 2-1 mya, Southern or Eastern Africa
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The Human Line (2.4 mya – 40,000 ya) similar to char. of Australopithecine line ave. cranial capacity of 656cc or greater many species existed at the same time Species: –Homo habilis: 2.4-1.6 mya, Southern or Eastern Africa –H. erectus: 1.7-1.8 mya, Eastern Africa and also in Asia (probably migrated there) –H. neanderthalensis: 500K – 40K ya, Europe –H. sapiens: 100K – present, many parts of the world
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H. neanderthalensis
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Trends illustrated by these two lines starting with Australopithecus afarensis and ending with Homo sapiens. jaw starts as tall and thick, becomes much smaller projecting face to flatter large to smaller molars larger brow ridges to no brow ridges increasing adaptation to bipedalism increasing brain size
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Possible ecology of Australopithecus and Homo Africa became drier, forest was replaced by clearings and grasslands –may have prompted bipedalism instead of arboreal life May have hunted with tools and used fire in order to colonize colder habitat and survive ice ages
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Adaptaions/Consequences of Bipedalsim foramen magnum (hole which spinal cord enters) moved forward arms became shorter and less powerful legs became longer and stronger (gluteus maximus) foot became rigid, shorter toes that became non-opposable made collecting food easier, can carry water, infants, tools, weapons...
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Cultural Evolution methods, customs, inventions, religion, language... are passed down generations important in human evolution and allowed more rapid change than genetic evolution our increased ability may be due to heritage of human experience, not more intelligence.
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