6 Human Diversity: The Emperor’s New Clothes Key Terms and Concepts oGeographic population oSubspecies oRace oRestricted gene flow oDevelopmental hypotheses oSelectionist hypotheses oTraditional social science oLactose intolerance oGene-culture co-evolution oRacism We covered a lot of new and unfamiliar ground in the previous lesson. We saw how natural selection operates and how it can produce changes in gene frequencies in a population, which constitutes evolution, and how the actions of selection can result in the evolution of characteristics that make individuals better at dealing with the ecological problems they may encounter. Most of the examples in that lesson were from non-human animals. However, there is no reason to expect that humans are exempt from natural selection. After all, as a species we have a great deal of phenotypic variability, much of it stemming from genetic differences. Further, we achieve different degrees of reproductive success (fitness) as a function of our phenotypes. Thus, all the required factors are present for human evolution to occur. Finally, our species radiated around the globe from our ancestral homeland in Africa and our ancestors faced a wide array of ecologies as they settled deserts, grasslands, rainforests, tropical islands, and frozen tundra. Our diverse anatomical phenotypes are testimony to the actions of natural selection on our ancestors. Although we should expect that physiological and behavioral characteristics would also exhibit great diversity, we need to look for evidence of such diversity. Lesson 6 79
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