Descriptionary

exaptation a new use for a body characteristic or com­ponent that originally evolved for a different purpose.

extinction the dying off of an entire species.

eugenics a term coined in 1883 by Francis Gal- ton designating a scheme to manipulate evolution by allowing only strong, intelligent people to breed, thus creating a super race of humans, an idea that fell out of favor after World War II.

evolution, theory of a widely misinterpreted term. Not a hypothesis, as popularly believed, but an expla­nation of evolution, based on observed, proven, and verified facts, that remains open to adjustments and additional information.

fitness overall health, strength, and ability to mate and successfully raise offspring, a major component in evolution.

genetic drift changes in a gene pool, due merely to chance rather than forces in the environment.

gradualism a theory of gradual change over time, in contrast with catastrophism.

heredity the inheritance of genes and traits from one's parents and grandparents.

hopeful monster slang term for a mutant or mutated animal that, through major structural change, has the potential to spawn a new type or variation of a spe­cies. Major mutations, though, are more often harm­ful than beneficial.

intelligent design a religious explanation for life and all its complexity, through which an all-powerful god designed and created all, discredited by main­stream science because it cannot be tested or proven.

macromutation a large-scale mutation, resulting in significant change in an animal. Most macromuta- tions are of no benefit and usually cause more harm than good.

micromutation a small or microscopic mutation, many of which are needed to bring about significant change in an animal.

missing link an outmoded term for a transitional animal or fossil, a developmental form between two distinctly different species.

mutation a mistake or change in genetic material, due to various forces, that along with other mutations may result in a change in an animal's traits. Muta­tions are often detrimental, but they are occasionally beneficial enough to be passed on successfully to gen­erations of offspring.

mutualism the development and adaptations of two species that evolve side by side and benefit from each other, as flowers and bees.

natural selection the natural law governing all life, through which organisms best adapted to their envi­ronments survive and pass on their successful traits to their offspring, while poorly adapted forms eventu­ally die out.

phyletic gradualism in contrast to punctuated equi­librium, the theory that evolution proceeds gradually over time, without big jumps or rapid changes.

phylogenetic tree see cladogram.

phylogeny the study of the relationships between species, as in a family tree.

punctuated equilibrium a theory that maintains that evolution does not always follow a slow or grad­ual path, and that change can come quickly in bursts, for example, as a result of catastrophic environmental changes, as when a comet or asteroid strikes the Earth and radically alters the climate, or when a species lives in relative isolation and changes to fit its own microenvironment.

Scopes monkey trial the famous 1925 trial of the teacher John Scopes, who was convicted of illegally teaching evolution to his students and was fined $100, the long-term effect of which was to prevent evolution from being covered in school textbooks until the 1960s.

selective pressures any environmental stresses, such as change of climate, drop in food sources, increased predation, or others, that force a life-form to either change environments or develop new traits, as through evolution.

speciation the change of one species and branching off into another, usually due to differences in sur­roundings.

taxonomy the biological classification of life-forms. trait a characteristic.

vestigial referring to a body part or trait that has diminished in size, function, or importance over the years, such as canine teeth in humans.

young earth creationism religious explanation of creation, based on the Bible, from which it is believed the Earth is only a few thousand years old, a notion discredited by mainstream science.

moon

albedo the percentage of light received from the Sun that is reflected off the Moon's surface (approxi­mately 7 percent). (The Earth reflects about 40 per­cent of received sunlight.)

Apennines a 600-mile-long mountain range with summits rising to 15,000 feet (one mountain, Mt. Huygens, rises to nearly 20,000 feet) located in the Moon's northeast quadrant.

apogee point of the Moon's orbit farthest from the Earth.