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14 Cards in this Set
- Front
- Back
Earliest members of Homo
and the traits that are used to include them in this genus and distinguish them from australopiths (4) |
1) Homo habilis
2) Homo rudolfensis 3) Homo ergaster Traits: 1) inferred dexterity = skill in performing tasks → tools 2) smaller face and jaws 3) smaller teeth 4) encephalization |
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Homo ergaster appears when and where
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1.8 mya - 600 kya
lower Pleistocene Africa |
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Cranial morphology of Homo ergaster
pleisomorphic 2 apomorphic 4 unique 2 |
Pleisomorphic:
• postorbital constriction • no forehead Apomorphic: • shorter, less prognathic face • taller skull • larger cranial capacity 500 - 1000 cc (still small) • smaller jaws and posterior teeth Unique: • occipital torus • large supraorbital torus → related to diet? for better adaption to tearing and biting? |
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Postcranial morphology of Homo ergaster
4 |
• long legs
• narrow hips and shoulders • shorter arms • barrel-shaped chest → fully committed to terrestrial life, first species with ability to run long-distances |
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Factors behind increased height and cranial capacity in Homo ergaster fossils
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Change in climate impacted food supply → increased access to animal protein
→ led to physical and cerebral growth |
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Homo ergaster and speech
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• Probably no spoken language
• size of vertebral canal in thoracic region is indicative of innervation of muscles and diaphragm • H. ergaster's is smaller → less precise control over these muscles → lesser ability to control breathing associated with speech |
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Homo ergaster and maturation
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rate of tooth enamel growth is indicative of rate of development
→ ergaster developed slower than australopiths, but faster than humans |
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Homo ergaster and sexual dimorphism
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• reduced from ancestors, but more than humans
• males 20-30% larger than females |
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Homo ergaster and circumstantial evidence for meat eating
3 |
• hand axes good for butchering
• faunal remains with cutmarks • H. ergaster teeth more suited for biting/tearing than for chewing |
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Homo ergaster and direct evidence for meat eating
2 |
• Hypervitaminosis A: Vitamin A poisoning from eating the liver of a large animal
• Terminal hosts for tapeworms: humans are terming hosts for 2 species of tapeworms, which diverged 1.7 - 0.8 mya, before animals were domesticated → therefore, our ancestors ate meat before this divergence |
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First hominin to leave Africa and evidence of this
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Homo ergaster
• primitive forms of ergaster found at the Caucasus Mountains • appear more like H. habilis and the australopiths → implies that ergaster left Africa early on |
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Pleistocene environmental changes and impact on hominin evolution
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• There is a cooling trend, with variability in the middle
• glacial periods → expansive deserts → restricted migration limited east <-> west • interglacial periods → returning forests → increased migration out of Africa into Asia north <-> south • middle Pleistocene ergaster evolution towards modern humans • new environments = variability of genes/gene flow (no longer isolated) = adaptations = evolution |
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Homo ergaster vs. Homo erectus
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Ergaster → Africa
Erectus → Asia • no difference in cranial capacity • erectus less behaviorally flexible |
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Homo erectus and tool use
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• associated with mode 1 tools
• mode 2 appears while there was an apparent meteor strike in Bose Basin, destroying the bamboo forest • got rid of bamboo which they could have been making tools out of • absence of bamboo created a need for new tools • created open grasslands, in which hand axes may have been better suited → appearance of mode 2 tools • mode 2 disappears when forest grew back |