Chapter 12 - Human Variation and Adaptation Flashcards Preview

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biological determinism

The con-cept that phenomena, including various aspects of behavior ( e. g., intelligence, values, morals) are governed by bio-logical ( genetic) factors; the inaccurate association of various behavioral attri-butes with certain biological traits, such as skin color.



The philosophy of “ race improvement” through the forced steril-ization of members of some groups and increased reproduction among others; an overly simplified, often racist view that’s now discredited.



Referring to species com-posed of populations that differ in the expression of one or more traits.



Loci with more than one allele. Polymorphisms can be expressed in the phenotype as the result of gene action ( as in ABO), or they can exist solely at the DNA level within non-coding regions.


slash- and- burn agriculture

A traditional land- clearing practice involv-ing the cutting and burning of trees and vegetation. In many areas, fields are abandoned after a few years and clear-ing occurs elsewhere.


lactase persistence

In adults, the continued production of lactase, the enzyme that breaks down lactose ( milk sugar). This allows adults in some human populations to digest fresh milk products. The discontinued produc-tion of lactase in adults leads to lactose intolerance and the inability to digest fresh milk.


population genetics

The study of the frequency of alleles, genotypes, and phenotypes in populations from a micro-evolutionary perspective.


gene pool

The total complement of genes shared by the reproductive mem-bers of a population.


breeding isolates

Populations that are clearly isolated geographically and/ or socially from other breeding groups.


Hardy- Weinberg equilibrium

the mathematical relationship expressing— under conditions in which no evolution is occurring— the predicted distribution of alleles in populations; the central theo-rem of population genetics.



In a physiological context, any factor that acts to disrupt homeostasis; more precisely, the body’s response to any factor that threatens its ability to maintain homeostasis.



a condition of balance, or stability, within a biological system, maintained by the interaction of physi-ological mechanisms that compensate for changes ( both external and internal).



Physiological responses to changes in the environ-ment that occur during an individual’s lifetime. Such responses may be temporary or permanent, depending on the duration of the environmental change and when in the individual’s life it occurs. The capacity for acclimatiza-tion may typify an entire population or species, and because it’s under genetic influence, it’s subject to evolutionary factors such as natural selection and genetic drift.


T or F. Skin color is a commonly cited exam-ple of adaptation through natural selec-tion in humans. In general, pigmenta-tion in indigenous populations prior to European contact ( beginning around 1500) followed a particular geographi-cal distribution, especially in the Old World ( Fig. 12- 6). In general, this pat-tern is still seen today. Populations with the greatest amount of pigmenta-tion are found in the tropics, and light-er skin color is associated with more northern latitudes, particularly the inhabitants of northwestern Europe. Skin color is mostly influenced by the pigment melanin,a granular substance substance produced by cells called melanocytes, found in the epidermis



neural tube

In early embryonic devel-opment, the anatomical structure that develops to form the brain and spinal cord.


spina bifida

A condition in which the arch of one or more vertebrae fails to fuse and form a protective barrier around the spinal cord. This can lead to spinal cord damage and paralysis.


evaporative cooling

a physiologi-cal mechanism that helps prevent the body from overheating. It occurs when perspiration is produced from sweat glands and then evaporates from the surface of the skin.



Expansion of blood vessels, permitting increased blood flow to the skin. Vasodilation permits warming of the skin and facilitates radia-tion of warmth as a means of cooling. Vasodilation is an ­involuntary response to warm temperatures, various drugs, and even emotional states ( blushing).



Narrowing of blood vessels to reduce blood flow to the skin. Vasoconstriction is an involun-tary response to cold and reduces heat loss at the skin’s surface.



Insufficient levels of oxygen in body tissues; oxygen deficiency.



Agents that transmit disease from one carrier to another. Mosquitoes are vectors for malaria, just as fleas are vectors for bubonic plague.



Continuously present in a ­population.



( zoh- oh- no ´ - (zoh-oh-no´- tic) Pertaining to a zoonosis ( pl., zoonoses), a disease that’s transmitted to humans through contact with nonhuman animals.



An epidemic that spreads through many populations and may affect people worldwide. Examples include HIV/ AIDS and the “ Spanish flu” pandemic of 1918- 1919.