From Africa to the World 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. Gracile - A. anamensis, A. africanus, A. afarensis, A. garhi Smaller stature, reduced teeth and jaw size, slighter larger brains. Led to genus Homo.

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

Why Bipedalism? Cons: Pros: 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%

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).

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.

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.

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.

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?