17.7: Key Terms

Adaptation: A fit between the organism and environment.

Adaptationism: The idea that everything is the product of natural selection.

Allele: A genetic variant.

Allometry: The differential growth of body parts.

Canalization: The tendency of a growing organism to be buffered toward normal development.

Epigenetics: The study of how genetically identical cells and organisms (with the same DNA base sequence) can nevertheless differ in stably inherited ways.

Eugenics: An idea that was popular in the 1920s that society should be improved by breeding “better” kinds of people.

Evo-devo: The study of the origin of form; a contraction of “evolutionary developmental biology.”

Exaptation: An additional beneficial use for a biological feature.

Extinction: The loss of a species from the face of the earth.

Gene: A stretch of DNA with an identifiable function (sometimes broadened to include any DNA with recognizable structural features as well).

Gene pool: Hypothetical summation of the entire genetic composition of population or species.

Genotype: Genetic constitution of an individual organism.

Hereditarianism: The idea that genes or ancestry is the most crucial or salient element in a human life. Generally associated with an argument for natural inequality on pseudo-genetic grounds.

Hox genes: A group of related genes that control for the body plan of an embryo along the head-tail axis.

Inheritance of acquired characteristics: The idea that you pass on the features that developed during your lifetime, not just your genes; also known as Lamarckian inheritance.

Natural selection: A consistent bias in survival and fertility, leading to the overrepresentation of certain features in future generations and an improved fit between an average member of the population and the environment.

Niche construction: The active engagement by which species transform their surroundings in favorable ways, rather than just passively inhabiting them.

Phenotype: Observable manifestation of a genetic constitution, expressed in a particular set of circumstances. The suite of traits of an organism.

Phrenology: The 19th-century anatomical study of bumps on the head as an indication of personality and mental abilities.

Plasticity: The tendency of a growing organism to react developmentally to its particular conditions of life.

Punctuated equilibria: The idea that species are stable through time and are formed very rapidly relative to their duration. (The opposite theory, that species are unstable and constantly changing through time, is called phyletic gradualism.)

Scientific racism: The use of pseudoscientific evidence to support or legitimize racial hierarchy and inequality.

Sexual selection: Natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.

Species selection: A postulated evolutionary process in which selection acts on an entire species population, rather than individuals.