anthology lecture 4 - 9/1/2011 Lasttenets

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9/1/2011 1 Last tenets The measure of biological evolutionary success is reproductive fitness. Those organisms that survive and leave behind the most viable young are most reproductively fit. Other genetic lines become extinct. Fitness here has no connotation of "adaptive perfection", simply that some organisms are better able to survive and reproduce than others. Natural selection works on individuals. Populations are units of adaptation. Natural selection is very opportunistic, working on what is available given earlier specific histories of evolutionary change. (hence "ramshackle" solutions to evolutionary problems e.g. different mechanisms of flight among insects, birds, bats). Natural selection can only create adaptations to immediately present conditions. In the long run, either a species goes extinct or it evolves into a new species. Two summary principles 1) ALL ORGANISMS SHARE DESCENT FROM SOME COMMON ANCESTOR. 2) NATURAL SELECTION IS THE MOST IMPORTANT MECHANISM BY WHICH POPULATIONS ADAPT AND, EVENTUALLY NEW SPECIES EMERGE. IF WE ACCEPT THIS VIEW, THEN ONE ISSUE FOR ANTHROPOLOGY IS THE BIOLOGICAL VARIATION IN SUCCESSIVE FORMS OF HUMANS THROUGH TIME. BIOLOGICAL EVOLUTION DOES NOT HAVE GOALS OR AIMS, IT ONLY HAS OUTCOMES; HENCE IT IS NOT USEFUL TO THINK OF IT IN TERMS OF "PROGRESS". BIOLOGICAL CLASSIFICATION OF MODERN HUMANS (Carolus Linneaus 1758) KINGDOM = ANIMALIA PHYLUM = CHORDATA CLASS = MAMMALIA ORDER = PRIMATES FAMILY = HOMININAE TRIBE = HOMININI (ALL LIVING AND EXTINCT FORMS OF HUMANS) GENUS = HOMO SPECIES = SAPIENS ALL LIVING OR EXTINCT FORMS OF HUMANS ARE CALLED HOMININS (MEMBERS OF THE FAMILY HOMININAE), WHETHER OR NOT THEY ARE OUR ANCESTORS OR EVOLUTIONARY OFFSHOOTS THAT ARE NOT ANCESTRAL TO US. What is an anatomically modern Human? Comparative definitions Reduction of face Increased globularity of the skull Key concepts to understanding Seletcion Individual organisms select mates from the opposite sex based on signs of potential reproductive fitness. Sometimes at the expense of survival Two examples Encephalization Brain to body ratio Increasing brain size and decreasing body size
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9/1/2011 2 The Red Queen Principle This evolutionary principle states that in many cases evolutionary changes do not confer an absolute advantage, but simply allow organisms to metaphorically “stay in the same place by running faster”. A population of predators might evolve better senses of smell, the capacity to run faster, etc Such changes put new selective pressures on the prey species, which might in response themselves adapt with greater speed, better camouflage, etc Even though both predators and prey species adapt, their relative fitness does not change (as it would, say, if only the predators adapted).
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This note was uploaded on 09/09/2011 for the course ANTH 009 taught by Professor Bedalleigh-ann during the Spring '08 term at Pennsylvania State University, University Park.

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anthology lecture 4 - 9/1/2011 Lasttenets

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