Exam 6: Human Variation and Adaptation

The indigenous communities in the tropical regions of the Americas are not as dark skinned as populations living in other tropical regions,because the dense vegetation in this continent blocks out much of the sunlight.

According to Allen's rule,the relative size of protruding body parts,including limbs,ears,tails,fingers,and toes,

Recall the mechanisms of genetic evolution discussed in the previous chapter.What is the relationship between gene flow and the existence of clines between human populations?

Populations in equatorial Africa and Papua New Guinea are phenotypically similar.They are both dark skinned,with similar hair and facial features.How would a typical racial model explain these similarities? How would evolutionary biology's explanation differ? Which model does a better job of explaining such data?

There is much greater variation within each of the traditional so-called races than between them.

What does the relationship between genetic traits and the prevalence of diseases such as malaria and smallpox illustrate?

Historically,scientists have approached the study of human biological diversity in two main ways: racial classification (now largely abandoned)versus the current explanatory approach,which focuses on understanding specific differences.

According to Thomson's nose rule,longer noses are more adaptive to colder climates than shorter ones.

The explanations given in this chapter for the differences in and distribution of skin color in populations around the world are examples of

How does the concept of race used by anthropologists today differ from the concept used by early biologists?

Bergmann's rule states that average body size tends to

Which of the following is the best example of how diseases have been powerful selective agents for humans,particularly before the arrival of modern medicine?

Native Australians are closer genetically to tropical Africans than they are to Asians.

One of the selective advantages of dark skin color in the tropics is that it reduces the susceptibility to folate destruction and therefore diminishes the likelihood of neural tube defects among human embryos.Folate is also necessary in men in order to maintain normal sperm production.

Skin color is a simple biological trait that is influenced by one gene and environmental exposure to sunlight.

Which of the following is the best plan of action for a light-skinned woman of childbearing age living in the tropics and concerned about giving birth to a child with neural tube defects (NTDs)?

The only chance for human racial classification schemes to work is to shift from using phenotypic to genotypic characteristics of human populations.

Traditional racial classification assumed that biological characteristics such as skin color were determined by heredity and remained stable over many generations.We now know that

Biologists have rejected the idea of three great races (white,black,and yellow)largely because it fails to account for Native Americans.

What is a phenotypic adaptation,and what makes it possible?