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Human Evolution. David Bugenhagen Andrew Torano. Dating for Dummies. Radioisotopes are used to determine the age of a rock C 14 is used for younger samples of rocks, between the ages of 1,000 and 100,000 years approximately K 40 is for anything older than 100,000 years
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Human Evolution David Bugenhagen Andrew Torano
Dating for Dummies • Radioisotopes are used to determine the age of a rock • C14 is used for younger samples of rocks, between the ages of 1,000 and 100,000 years approximately • K40 is for anything older than 100,000 years • Both of these are used because they decay in very predictable patterns and the half-life of each can be measured fairly accurately • The half life of a rock or fossil is determined based on how long it takes the electrons of the radioisotope to decay • The age of fossils is determined by carbon dating in much the same way as rocks, except carbon is used every time
We have monkey parts • Opposable thumbs • Bipedal hips • Binocular vision eyes • Mobile arms and legs, shoulder and knee joints can rotate many more directions than most mammals • Modified skull for bipedal posture
Our REALLY BIG family tree • See giant posters on wall
H.NeanderthalvsH.Sapien: The ShowDown • A number of Australopithecus and Homo species coexisted in similar parts of Africa at the same time • It is presumed that Homo Neanderthalensis and Homo sapiens coexisted in Europe, H. sapien is attributed with the extinction of H. Neanderthalensis
Looking for Dead Stuff It has been hard to find fossils that clearly show the change of species from one to another. Fossils rarely result when an animal dies because: •Decomposition is fast so soft body parts are rarely fossilized •Scavengers break up skeletons and chew up bones •The conditions have to be just right for fossilization to occur Only a small fraction of all the fossils have been found, so there are large gaps in the fossil record
Bigger is Better A larger brain allows for: More complex tools A mastery of fire for cooking, warmth, and protection More advanced weapons More behavioral flexibility As our brains have enlarged, we have eaten more meat, because easier to hunt.
Are we still Evolving? • Genetic Evolution refers to genetic changes that have occurred over the evolution of hominids • Cultural evolution is the changing of ideas held and actions and the transmission of these ideas through social learning from one generation to the next.