PSYC14H3 Chapter Notes - Chapter 11: Lactase, Visual Acuity, Standard-Definition Television
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Two distinct reasons why theirs variation in humans: there are innate biological differences across cultures, there are acquired biological differences across cultures. Modern humans (homo sapiens) first emerged approximately 100,000- 200,000 years ago, and they all lived in africa until approximately 50,000- 60,000 years ago when some of them migrated elsewhere. Moreover, there"s more genetic variability among africans (who have had up to. 200,000 years to ac- cumulate genetic changes) than there is between africans and people of other cultural backgrounds (who have had only up to 60,000 years to accumulate changes; Skin color is an example of an adaptive response to climatic differences among populations, and these represent one large domain of genetic differences across populations. Differences in climate exert a strong selective force, such that those individuals who are better adapted to the local climate will have more surviving offspring. Genetic adaptation to the local climate and pathogens are cases in which geographical factors have shaped the genotype.