Apes to Man

Human Evolution Human evolution is characterized by several types of changes in phenotype: Note: obviously, these aren't the only phenotypic changes characteristic of the human species, but are more noteworthy in regards to human evolution.

Changes in brain size & skull shape Smaller to larger brain capacity Spinal insertion moves from rear to base of skull

Comparative Brain Sizes

Hand Shape Development of more flexible opposable thumb Allowed advanced tool use

Pelvis shape Allowed early hominids to stand & walk upright Gave advantage of being able to see around them on the savannah

Spine Shape Changed from "C" shape to "S" shape

Jaw Size Jaw has reduced in size, reflecting changes in species diet Size of teeth have generally decreased, especially canines

Hominid changes over time

Timeline of human ancestry ~ 14-16 Million Years to (?) - Ramapithecus & Proconsul Earliest Ape-like ancestor. Did not walk upright Similar in size to the chimpanzee, but stockier

Genus Australopithecus ~ 3.5 - 1 million years - Genus Australopithecus Several Species of this genus including A. afarensis, A.africanus, & A. boeisi Earliest is Australopithecus afarensis Very much apelike with an important feature. Was able to walk upright

Australopithicenes

Australopithicenes

Homo Habilis ~ 2 - 1.5 million years - Homo habilis "handy man". Larger than Australopithecus Larger brain Was first to use stone tools.

Homo habilis

Homo habilis contd.

Homo erectus ~ 1.5 Million years - ~ 80,000* years . Homo erectus. Larger than H. habilis Larger brain Smaller face Was the first to use fire Allowed man to "break out" of Africa into Europe & Asia

Homo erectus

Homo neanderthalis ~130,000 - 30,000 years. Homo neanderthalis "Neanderthal man" Probably not a direct ancestor - but another offshoot from H. erectus Shorter, stockier, stronger than modern man. Adapted to ice age. Larger brain size than modern man. Buried dead with flowers - first evidence of religeous/symbolic thinking.

H. neanderthalis

“Modern” man ~ 100,000 years to present - Homo sapiens (modern man). Appears to have originated from H. erectus in Africa, then migrated outwards to Europe & Asia. Replaced existing species H. erectus & H. neanderthalis

“Radiation” theory of H. sapien evolution

“Parallel” theory of H. sapien evolution

Current phylogeny of H. sapiens

How to make a human: Millions of years ago, a majority of northern Africa was rainforest. Ancestors to man Rapapithecus and Proconsul, were full arboreal apes living in these forests.

Changes However, approx. 5 mya the great rift valley formed in east central Africa.

Problems….. The effect of this rift was to… Isolate the ape population from their peers in the west. The rift also created a “rainshadow desert” to its leeward side.

Change of environment. This change in precipitation changed the landscape of the region from rainforest to savannah. The apes needed to develop a new form of transportation since they could no longer brachiate through the trees. Thus, they evolved the ability to walk upright.