Early Hominins Anth 1001
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This 2 page Class Notes was uploaded by Aafreen Afzal on Wednesday March 30, 2016. The Class Notes belongs to Anth 1001 at George Washington University taught by Shannon C. McFarlin in Spring 2016. Since its upload, it has received 13 views. For similar materials see Biological Anthropology in anthropology, evolution, sphr at George Washington University.
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Date Created: 03/30/16
Early Hominins Lecture March 30th 2016 Human-like primates Miocene: Age of apes, earliest human ancestors Possible location may have been Ethiopia, Chad, Kenya. East and central Africa East African Rift System had been a good location for these ancestors to thrive What makes a Hominin? 1. Bipedal walking 2. Characteristics of dentition 3. Elaboration of material culture 4. Significant increase in brain size 5. Long developmental period and lifespan Locomotion of ancestors ● Some believe that we had non-knuckle walking ancestors ● Most believed is that we had knuckle walking ancestors Adaptive explanations for the origin of bipedalism ● Social factors ○ Ability to provide for the family in context of the evolution of monogamous systems (carry tools, children, etc) ○ Moving across forested patches with higher energetic efficiency ○ Finding food and spotting predators Earliest evidence of bipedalism: Sahelanthropus tchadensis, Chad 7-6 mya ● Digitally reconstructed -> more vertical face, higher skull vault ● Smaller canines, no C-P3 honing complex ● Biped? - position of foramen magnum ● But primitive in other respects (brain size, U-shaped dental arcade) Orrorin tugenensis , Kenya 6 mya ● Fragmentary cranial and postcranial remains ● Femoral morphology is indicative of bipedal locomotion ● Dental morphology is apelike Ardipithecus ramidus and Ar. k adaba, Ethiopia 5.8-4.4 mya ● Intermediate canine size between apes and later hominins ● Relative small brain, prognathism as in apes ● More forwardly placed foramen magnum, consistent with bipedalism ● Reduced canine size ● Loss of C-P3 honing ● Minimal sexual dimorphism ● Mosaic of characters for both bipedalism and climbing ● Short and broad ilium (unlike chimps) ● Ischial surface is primitive ● Foot retains a divergent big toe, but lacked other features for suspension, vertical climbing and knuckle walking seen in apes ● Combination of primitive and derived traits. Evidence of its ancestral position as being an early ape or an evolutionary side branch for others (partially arboreal, facultative biped, feminized canine, woodland omnivore) Lovejoy’s model for the origins of bipedality Bipedalism -> Vested provisioning Vested provisioning -> Loss of honing canine, reduced intrasexual agonism (male- male competition) and increased social adhesion, ovulatory crypsis