Chapter 6 Flashcards
In the early twentieth century, anthropologist Franz Boas described changes in skull form among the children of Europeans who had migrated to North America. He found that the reason for these changes could not be explained by genetics. His findings underscore the fact that
phenotypic similarities and differences don’t necessarily have a genetic basis.
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
a biological similarity such as skin color is also the result of natural selection working among different populations that face similar environmental challenges.
East Asians who have migrated recently from India and Pakistan to northern areas of the United Kingdom have a higher incidence of which two medical conditions than the general British population?
Rickets and osteoporosis
Bergmann’s rule states that average body size tends to
increase in cold climates and decrease in hot ones.
According to Allen’s rule, the relative size of protruding body parts, including limbs, ears, tails, fingers, and toes
increases with temperature.
Which of the following statements about the concept of race as applied to humans is TRUE?
It is a discredited concept in biology.
According to contemporary scientists, racial distinctions are based on
culture
Historically, scientists have approached the study of human biological diversity in two main ways: racial classification (now largely abandoned), and the current explanatory approach, which focuses on understanding specific differences.
true
Humanity ( Homo sapiens) lacks distinct races because human populations have not been isolated enough from one another to develop into discrete groups.
true
There is much greater variation within each of the traditional so-called races than between them.
true
Higher amounts of melanin in the skin inhibit the body’s ability to manufacture vitamin D. This confers an adaptive advantage in environments with excessive sun exposure.
true
Rickets is caused by an overabundance of vitamin D in the body.
false
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.
true
According to Thomson’s nose rule, longer noses are more adaptive to colder climates than shorter ones.
true
This lecture’s discussion of lactose tolerance highlights how genes and phenotypic adaptation can work together to produce human biological diversity when other foods are scarce and milk is available (as it is in herding societies).
true
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?
Gene flow, the exchange of genetic material across populations, results in clines, which are gradual shifts in gene frequencies between neighboring groups.
What term refers to an organism’s evident traits, its “manifest biology”
phenotype
In understanding the problems with attempts at human racial classification, why is it important to know the difference between genotype and phenotype?
Attempts at human racial classification have typically used phenotypic traits like skin color as markers of common ancestry, but many such traits do not reflect shared genetic material. Instead, they are often the result of different populations biologically adapting to similar environmental stressors in similar ways.
A gradual genetic shift in gene frequencies between neighboring populations (a continuous gradient) is called
A cline
What became the foremost cause of human mortality 10 kya?
Infectious diseases
