Hominid Evolution

Origins of Hominids Most crucial change was Bipedal Locomotion Other changes include Expansion of the brain, larger birth canal, reduction of face, teeth and jaws All of these occurred 2 million yrs. After bipedalism Journal Entry 1

Why did Bipedalism occur? See farther Carry food Carry tools and weapons

Australopithecines First definite Hominids Genus of Hominids until C. 2 Mill yrs. Ago Somewhere b/t 3 and 4 mill. yrs ago. At Laetoli footprints found proving bipedal locomotion Although Bipedal, still may have spent time in trees for sleep and shelter

Types of Species Australopithecus afarensis Australopithecus africanus Australopithecus robustus There are more  Think of hominids as a Bush, not a timeline!

Australopithecus Afarensis Debate as to whether diff. species or not Footprints found to prove bipedalism Between 3 and 4 million years ago

Australopithecus Africanus Jaw of ape Teeth of humans S-shape spine similar to man

Afarensis vs. Africanus Features of skull, teeth, and jaws that are less apelike in africanus Some debate different species

Australopithecus robustus 2-1 million years ago Larger molars and premolars Smaller canines Well-developed cranial crests and ridges Much heavier Taller: 4.5- 5 ft. tall

Ancestor? Australopithecus robustus is not thought to be an ancestor to the Homo species Lived during same relative time as Homo species

Changes Expansion of brain Reduction of face, teeth, and jaws Babies born less mature at birth Journal Entry #2

Expansion of the brain Had relatively small cranial capacities Reason? Why would brain size have increased? (Think Evolution types) Possible reasons: Increased as a result of tool making

Reduction of Face, Teeth, and Jaws Lower face not as protruding Reduction in size of Face Cheek bone Jaw

Now on to species of Homo Different ideas on how Homo genus evolved Some say from Africanus Some say from Afarensis About 2 millions years ago

Homo habilis Larger brain absolutely and relatively than Australopithecus Found in East Africa Slightly Larger and more developed brain Stone tools?

Homo erectus 1.6 to 1.3 millions years ago Skull generally long, low, and thickly walled Flat frontal face Prominent brow ridges Relatively small teeth modern arrangement

Cont… Fully developed vision area of brain Larger areas of speech, sensory, memory and motor areas of brain Neck down, almost same as Homo sapiens

Fire Fire first appears 1.5 mill. Years ago Only able to spread out after development of fire Journal Entry

Stone tools Acheulean “hand axe” 1.5 mil. Years ago Used for butchering, digging, pounding Toolmaker first shaped the core, and prepared a striking platform at one end Knock off flakes

Hunting Homo erectus began to hunt medium sized animals Spears, stone throwing, and fire Needed to plan and work in groups

Neanderthal Becoming Human