NBB 201 – 3rd Day

NBB 201 – 3rd Day - HumanEvolution 02:03...

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Human Evolution 02:03 Proconsul: ancestor of all ape species Sivapithecus: ancestor of orangutan ***Humans didn’t evolve from chimps or any other living ape species!! = Impossible HOMININ: a fossil specimen that is more closely related to modern humans than to modern chimpanzees; bipedalism and reduced canine teeth Many hominin species living at the same time (~between 4-1 million years ago) We aren’t quite as special as we thought we were Hominoid: all living apes + ancestors Fossil Evidence: (1) organism must become buried in sediment, (2) bone or teeth must mineralize, (3) surrounding sediment must harden Very hard due to scavengers/environment = why we don’t have a very strong fossil record We shared a common ancestor with chimps (diff. from us and chimps) about 6 MYA How do we know? The molecular clock – human DNA differs from chimp DNA by only 1.5% Rate at which these mutations/changes occur is pretty steady (1 sec = 50K Yrs) We have a good fossil record for orangutans 16MYA/4% = 4MYA/1% ---> 1.5%(4MYA/1%) = 6MYA Condense 4.5 billion years (history of Earth) into a single calendar day: (One second = 50,000 years) At 120s (11:58 PM) chimps and humans emerged---VERY recent (anatomically modern humans, last 2s of the day) Paleoanthropologists: paleontologists who hunt for hominins Skeletal Adaptations for Bipedalism (1) Human spine exits from the center (feramen magnum); ape spine exits from rear of skull (2) Human spine is S-shaped; ape spine has a slight curve--C-shaped (3) Human toe is adducted and has arched feet
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(4) Human pelvis is bowl-shaped; ape pelvis is longer and more narrow (5) Human femurs angle inward to the knees; ape femurs angle out a bit (6) Human knee can support more weight than ape knees There are several different hypothesized phylogenetic trees Australopithecines (genus= Australopithecus) Gracile (lightly built) – A. afarensis (East Africa) and A. africanus (South Africa) Eat softer foods/smaller skull Gave rise to robust, and became extinct afterwards
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NBB 201 – 3rd Day - HumanEvolution 02:03...

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