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Anthro Lecture 2-14

Anthro Lecture 2-14 - Anthro Lecture 2/14 I...

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Anthro Lecture 2/14 I. Australopithecines grew up quickly a. In humans, crown of canine is fully developed before first premolar b. In chimps, crown of canine not fully developed until after first premolar c. Examine teeth of A. africanus child d. Compare age estimates based on different teeth using human and chimp development pattern e. Data fit chimp development better f. Australopithecines grew up more quickly than humans II. Estimates of body size a. Suggest strong sexual dimorphism b. Males 4’8 to 5’, 90-110 pounds c. Females 3’6 to 3’11, 66-77 pounds d. Males weigh 30-50% more than females e. Not pair-bonded III. Australopithecine brains and faces a. Ape-like b. Lower part of face protrudes (prognathic), though less so in later species c. Most Australopithecine species brain are about 400-500 cc d. Extant chimps about 370 cc e. Modern human brains average 1400-1500 cc (range: 1200-1700) f. Note smaller canines and front teeth in Australopithecus compared to chimp g. Some trend to brain enlargement i. About 2.4 MYA, larger brained australopithecines appeared ii. Brain = 775 cc (25% increase) iii. Teeth and jaws more like modern humans
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iv. Very little known about body size; relative brain size may be only slightly larger IV.Paranthropines a. Bipedal apes with very large molars b. Jaw and skull reorganized for heavy chewing i. Sagittal crest enlarges attachment surface for temporalis muscle that works jaw ii. Very large molars iii. Cheekbones flared out to make room for enlarged temporalis iv. The paranthropus jaw required massive musculature c. What are the big teeth good for? i. Animals that eat tough plant material often have big molars and small anterior teeth ii. Wear patterns on teeth suggest they ate hard things, like seeds and nuts iii. Chemical analyses of fossils suggest they might have eaten meat too d. Kenyanthropus platyops i.
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Anthro Lecture 2-14 - Anthro Lecture 2/14 I...

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