Human Evolution

When do the first fossils with some primate characteristics appear?

60mya, in the Palaeocene era

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Which primate today is thought to be the closest living relative of these fossils?

Tree shrews

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What are the characteristics of primates?

Prominent scapula and clavicle- mobile shoulder joint, 5 functional digits on limb & opposable thumbs, reduced snout, enlarged brain, forward pointing eyes, reduced number of teeth, reduction tending to 2 mammary glands, one young per pregnancy

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What is facultative bipedalism?

The capability to walk on 2 legs

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What are prosimians?

(Lemurs, lorises, tarsiers, bush babies) Mostly small, solitary, nocturnal, arboreal (live in trees), insectivores, long snouts, relatively small brains

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Anthropoids

Monkeys and apes (split into Platyrrihini and catarrhini)

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Platyrrihini

Broad nosed, new world monkeys, 30mya developed

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Catarrhini

Narrow nosed, old world monkeys and apes, around 23mya developed

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Describe an anthropoid

Larger, with relatively larger brains, frugivorous (feeds on fruit), diurnal (active in daytime), complex group organisations

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Hominoidea

Apes, flatter torso, wider shoulders, thorax and hips, long clavicle, dorsal and scapula, no tail

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Hominid

Humans, arched palate, bow-shaped dental arcade, reduced canines, thicker enamel, foramen magnum under skull rather than posterior, implying upright stance, loss of curvature in toes, flat footed walking rather than grasping

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When did hominids diverge?

Around 6mya from chimps and 8-10myz from gorillas

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What is Lucy?

40% complete skeleton dating from 3.2mya in Ethiopia

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What did Mary Leaky find?

Similar remains to Lucy and 3 sets of bipedal walking footprints (suggesting striding rather than ape-like waddling)

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Homo Habilis

East African fossil fragments, 2.4-1.6mya, larger cranial capacity, in association with stone tools and animal bones with cut marks

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Homo erectus

Smaller teeth, jaws and arm bones, height 1.85cm, delayed tooth-eruption in young, implying childhood

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Neanderthal

First found in western Germany, cranial capacity similar to H.sapiens but occipital rather than temporal, bifaces tools but no spears or arrows, ritualised burials

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Homo sapiens

Earliest specimen 195ka in Ethiopia, restricted to Africa till reached Middle East, 2nd separate and later costal dispersal

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Hypothesis 1 for explaining dispersal from Africa

Intellectual/ cultural revolution 50-100ka facilitated emigration (but cranial capacity, relative to body size, had already stopped growing >200ka

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Hypothesis 2

Climate change prompted exploitation of grasslands and their herbivores in what is now Sahara, then costal/ wetland resource exploitation opening routes to Europe Asia and Australia

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Why did neanderthals go extinct?

Occurred in Europe through a period of repeated ice ages, swamped by hybridisation with humans? Population fragmentation may have increased extinction risk, however humans faced same conditions and survived?

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What features make us human?

Flattened feet, no opposable big toe, upright stance for predator detection in grassland and reduced exposure to sunlight, athletic capacity for avoiding predators, reduced sexual dimorphism

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Human Evolution

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