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Origins of Genus Homo

Origins of Genus Homo. From Africa to the World. Early Hominids. Australopithicines splitting into 2 groups: Robust – A. aethiopicus , A. boisei , A. robustus Large teeth and jaws, some with pronounced sagittal crest. Evolutionary dead end .

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Origins of Genus Homo

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  1. Origins of Genus Homo From Africa to the World

  2. Early Hominids • Australopithicines splitting into 2 groups: • Robust – A. aethiopicus, A. boisei, A. robustus • Large teeth and jaws, some with pronounced sagittal crest. • Evolutionary dead end. • Gracile - A. anamensis, A. africanus, A. afarensis, A. garhi • Smaller stature, reduced teeth and jaw size, slighter larger brains. • Led to genus Homo.

  3. Advent of Bipedalism Required anatomical shifts occur during evolution of genus Australopithecus. Changes include: Position of foramen magnum Orientation of leg bones Pelvis changes

  4. Why Bipedalism? • Cons: • more visible to predators. • Less biomechanically efficient. • Damage to 1 of 2 legs is lethal, 1 of 4 is not. • Pros: • Transport of items in hands • Better reconnaissance • Carry infants • Reduce heat stresses • Upright postures reduce heat loads by up to 60%

  5. Why else Bipedalism? • Brain and body temps coupled in hominids. • Brain can only grow as large as cooling allows. • Bipedalism reduces heat load on body, combined with better ‘plumbing; allows for increase in brain size. • Hair loss on body may allow for more effective sweating • Hair on head may allow for solar radiation shield. • Reflectance of hair is coded by same gene responsible for some putative IQ determinants. (Look into this Thorp).

  6. Homo habilis • ‘Handy man’ • Bipedal as evidenced by foot bone alignment. • Either highly sexually dimorphic or 2 subspecies exist. • Brain size larger than Australopithecines but still smallish at ~600-700cc. • Brain cooling was markedly different from Australopithecines. • Possessed small openings in skull for veins to bring cooled blood from face and scalp into brain. • Teeth reduced in size from Australo. • Oldowan tool tradition.

  7. Homo erectus origins • Alternate naming conventions include: • Homo ergaster (African Homo erectus species, H. erectus reserved for Asian specimens). • Homo antecessor (possible Spanish subgroup) • Homo heidelbergensis (named for German fossil find, used by some to designate all European Homo erectus fossils from 500,000ya to appearance of Neanderthals. • Found outside of Africa • Result of single or multiple migrations.

  8. Homo erectus characteristics • Larger stature, more heavily muscled. • Possible decreased sexual dimorphism. • Skull possesses mixed set of attributes: • Prominent browridges • Increased cranial capacity (see next slide) • Brain development is similar to that of modern humans, suggests increased cognitive ability and speech.

  9. Homo neanderthalensis • Stocky muscular build • Large skull, large cranial capacity and occipital bun. • Midface projects outwards, large nasal area. • Sophisticated tools – Mousterian tradition • Evidence of tool kits containing specialized implements. • Allowed for improved clothing, shelter, hunting, etc. • Tool making skills used in artistic endeavors? • Ritual burial?

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