Basic Trends in Hominid Evolution SC.912.L.15.10

Homo sapiens are of the order Primates What is a primate? Round heads with flattened faces. Brains that are relatively large when compared to body size. Primate brains are also much more complex than any other land mammals. Diverse behaviors and social interactions reflect the complexity of their brains. (language and tool making)

Primates also… Opposable thumbs – the primates opposable thumbs enable it to grasp and manipulate objects. Vision – vision is the dominant sense for primates, which is binocular. Brain volume – a primate has a large brain relative to it’s body. Arm movement – shoulders are unique on primates which enable wide range of arm movements. Flexible joints – primate elbow and wrists joints make the arms unique. Feet – a primate’s feet can grasp objects, but the degree of effectiveness of a primate’s feet can vary.

Hominids 5-8 million years ago in Africa a population that spawned chimps and humans diverged into two lines. • One line gave way to chimps, and the other line into modern day humans. • The two lines are collectively called hominids. • Hominids are primates that can walk upright on two legs and include gorillas, chimps, bonobos, and humans.

Australopithecus

Australopithecine Both apelike and humanlike. • Lucy, was discovered by paleoantrhopologist Donald Johansson, that dates back to 3.2 million years ago. • Lucy’s skeleton was from a new species called australopithecine afarensis. • The unique thing about Lucy was the size of her brain case. Lucy had an incredibly large brain. • Anthropologist theorize that Australopithecine is the ancestry of modern humans.

Big Brains = Tools 1964 Louis and Mary Leakey described a skull that matched more closely with modern human skulls. • The larger brain case and smaller jaw and teeth indicated human lineage. • The Leakey’s named the species Homo habilis, which means handy human. • This name was dubbed because of the usage of tools. • Radiometric dating estimates life about 1.5 –2.5 million years ago.

Human Evolution

Homo erectus Homo erectus and like fossils are found in Africa, Asia, and Europe and are dated between 1.9 and 0.3 mya. Larger brain and flatter face than Homo habilis. Much taller than previous hominids. Believed to have first appeared in Africa and then migrated into Asia and Europe. First hominid to use fire.

Homo erectus Using Tools Re-creation of a Pleistocene setting in which Homo erectus use fire & stone tools

Neanderthals Neanderthal (H. neanderthalensis) skeletons were first discovered in Germany’s Neander Valley. Skeletons date back 200,000 years. Massive brow ridges with protruding nose, jaws, and teeth. Heavily muscled. Culturally advanced. Manufactured variety of tools.

Reconstructed Neanderthal skull characterized by prominent heavy brow ridges and week chin

Neanderthals (190,000 – 27,000 yrs ago) Flaked stones that fit in wood handles. Buried their dead with spices and bedding. Built sturdy huts. Made flutes! A flute formed from a femur & 4 remaining holes.

Cro-Magnons – Homo sapiens Oldest fossils to be designated H. sapiens. Modern humans who entered Asia and Europe from Africa 100,000 years ago. Made advanced stone tools. Accomplished hunters. Hunted cooperatively. First to have complex language?

Homo Floresiensis (hobbits) - one meter high - lived in Flores 12,000 yrs ago - Upright posture - 380 cc cranial size (like a chimp)

The shapes & sizes of hominid heads can be seen to evolve with time.

Australopithecus vs. Modern Australopithecus, 4-3 myrs ago Modern human Chimpanzee

Cranial Comparisons Homo Erectus Neanderthal Homo Sapiens

Hominid Evolution Review Increase in brain size over time Smaller jaw size over time With larger brain came tool use and eventually language