ANT1Lecture18

ANT1Lecture18 - Anthropology 1 Winter 2008 Human...

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Unformatted text preview: Anthropology 1 Winter 2008 Human Evolutionary Biology A. africanus Sahelanthropus Orrorin Ardipithecus 1 2 3 4 5 6 A. afarensis P. boisei P. robustus A. anamensis A. garhi P. aethiopicus M Y A H. habilis H. ergaster Hominin phylogeny Which fossil species are more closely related to each other? First approximation: Assume species with similar phenotypes (skeletons) are closely related to each other Use degree of similarity to reconstruct evolutionary relationships (phylogeny) Phylogeny reconstruction Time since divergence Phenotypic Distance First approximation works for neutral phenotypic features Problem with first approximation Natural selection Natural can slow down or speed up divergence rates, invalidating first approximation Natural selection can confound phylogeny reconstruction in 2 ways Similar directional selection pressures Different amounts of stabilizing selection Directional selection can cause problems because . . . Different types of similarities Analogy (homoplasy) Similarity that results when similar directional selection pressures produce similar adaptations Homology Similarity that results from closely shared ancestry (evolutionary history) Analogies can cause problems Analogies can cause problems Consider 3 species Human Chicken Platypus Analogies can cause Problems Consider 3 species Human Chicken Platypus Lactates Bipedal Human Yes Yes Chicken Yes Platypus Yes Analogies can cause Problems Consider 3 species Human Chicken Platypus Lactates Bipedal Human Yes Yes Chicken Yes Platypus Yes Analogies can cause Problems Consider 3 species Human Chicken Platypus Lactates Bipedal Human Yes Yes Chicken Yes Platypus Yes Analogies can cause Problems...
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This note was uploaded on 04/15/2008 for the course ANT 001 taught by Professor Mchenry during the Winter '08 term at UC Davis.

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ANT1Lecture18 - Anthropology 1 Winter 2008 Human...

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