Origins of Modern Humans

http://www.pbs.org/wgbh/nova/evolution/building-fossils-faces.html

Terms Anatomically Modern Humans (AMH) Early Modern Humans (EMH) The modern form of the human species, Homo sapiens, dates back to 200,000 years ago.

Carl Sagan’s Cosmic Calendar

Homo sapiens Likely evolved from Homo heidelbergensis. Earliest evidence for H. sapiens is found in Africa, dating to ~200,000 years ago. The Omo site, in Ethiopia: 195,000 years ago.

Omo 1 skull Well rounded occipital High skull Chin

Anatomically modern humans in Africa Have been found at a number of sites (Border Cave in southeast Africa, Klasies River Mouth in South Africa) These show a presence of anatomically modern humans in Africa between 100,000 and 200,000 years ago.

Anatomically Modern Humans In the Middle East: sites in Israel date to 92,000 years ago. In Australia: 60,000 – 46,000 years ago. East Asia: roughly 60,000 years ago. Europe: 46,000 -- 41,000 years ago.

Physical Characteristics of Anatomically Modern Human Skulls Vaulted cranium. No occipital bun. Back of the skull is very rounded. Reduced prognathism (face doesn’t protrude much). Mental eminence (chin). No prominent brow ridges. More gracile than earlier Homo species. One of the most well-known examples of early Homo Sapiens is from Cro-Magnon, France.

Cro-Magnon One of the most well-known examples of early Homo Sapiens is from Cro-Magnon, France. Discovered in 1868 (road construction revealed a rock shelter within a limestone cliff).

Homo Floresiensis “The Hobbit.” 94,000 to 12,000 years ago. Liang Bua Cave on the island of Flores, Indonesia. Adult: 3.5 ft; cc = 417 Evidence for use of fire and group hunting.

Island Dwarfism The process by which natural selection favors smaller body size on an island with limited resources, which leads to dwarfed species. This leads to species which are much smaller than their ancestors. Is H. floresiensis a dwarf species of H. erectus? (Stone tools dating to 840,000 years ago.)

Homo Floresiensis Flores: The island is separated from the rest of Indonesia by a deep ocean trench, so deep that even at times of lower sea levels, it would have been unable to cross unless by some type of ‘raft.’

Homo Floresiensis Island Dwarfism of H. erectus New species Arguments: the remains could be exhibiting some kind of pathology which made them small (microephalic [small headed]) But though no other skulls have been found thus far, other remains of multiple individuals have, and they support the hypothesis that the Hobbit is a species not suffering from a pathology.

Homo Floresiensis Most anthropologists agree this is a different species, however the origin is less clear: Virtual endocasts have been made and show that the H. floresiensis’ brain most resembled that of H. erectus. Australopith body proportions and small brain. 94,000 to 12,000 years ago. We need more evidence from earlier in Flores’ prehistory to find out if H. floresiensis descended from H. erectus or another small hominid.

Key terms for cultural behaviors Upper Paleolithic: General term referring to the stone tool technologies of anatomically modern H. sapiens. Lower Paleolithic: General term to referring to stone tool technologies of H. habilis, H. rudolfensis, and H. erectus. Middle Paleolithic: A general term referring to stone tool technologies of H. heidelbergensis and the Neandertals.

Tool Technologies So many different types of tools are associated with anatomically modern H. sapiens that a single tradition would be impossible to define.

Tool Technologies Five prominent tool traditions (of Europe): Chatelperronian Aurignacian Gravettian Solutrean Magdalenian

Tool Technologies Upper Paleolithic: More variation than in previous cultures. Much more precisely made. Development of blades Blades: are defined as being at least twice as long as they are wide. Made by removing long narrow flakes off of a prepared core. The core is hit by antler or bone which is in turn hit by a stone.

Tool Technologies Burin: small tool with an extremely sharp edge, used to cut, whittle, and engrave bone. Bone was used to create needles, points, knives, and harpoons, as well as art. Bone tools first appeared with H. sapiens. They are not found in association with earlier Homo species. Bone tools date to about 45,000 but there is evidence from Zaire which suggests an earlier age of 95,000 years ago.

Tool Technologies The last stage of the Upper Paleolithic, the Magdalenian, saw even more advances in technologies: Spear-thrower, called the atlatl Wooden or bone hooked rod that extended the hunters arm, which enhanced the force and distance of the spear throw.

Tool Technologies By producing many more specialized tools people in the Upper Paleolithic had more resources available to them. These more effective tools may have had an impact on the biology of these populations. Why??

Tool Technologies More effective tools, fire, more efficient food processing all mean that anatomically modern H. sapiens wouldn’t have required the large teeth and facial skeletons of earlier populations.