idealism: The philosophical theory that there are fundamental non-material "ideas," "plans," or "forms" underlying the phenomena we observe in nature. It has been historically influential in classification.
immigration: The movement of organisms into an area.
immutability: The ability to withstand change.
induction: The process of deriving general principles from particular facts.
inference: A conclusion drawn from evidence.
inheritance of acquired characters: Historically influential but factually erroneous theory that an individual inherits characters that its parents acquired during their lifetimes.
insectivorous: Feeding largely or exclusively on insects.
intelligent design: The non-scientific argument that complex biological structures have been designed by an unidentified supernatural or extraterrestrial intelligence.
intron: The nucleotide sequences of some genes consist of parts that code for amino acids, and other parts that do not code for amino acids interspersed among them. The interspersed non-coding parts, which are not translated, are called introns; the coding parts are called exons.
inversion: An event (or the product of the event) in which a sequence of nucleotides in the DNA is reversed, or inverted. Sometimes inversions are visible in the structure of the chromosomes.IQ: An abbreviation of "intelligence quotient," usually defined as the mental age of an individual (as measured by standardized tests) divided by his or her real age and multiplied by 100. This formulation establishes the average IQ as 100. The usefulness and reliability of IQ as a measure of intelligence has been questioned, in part because of the difficulty of devising standardized tests that are free of cultural biases.
isolating mechanism: Any mechanism, such as a difference between species in courtship behavior or breeding season, that results in reproductive isolation between the species.
isolation: Synonym for reproductive isolation.
isotope: An atom that shares the same atomic number and position as other atoms in an element but has a different number of neutrons and thus a different atomic mass.
Jablonski, David: Paleontologist and professor in the Department of the Geophysical Sciences of the University of Chicago. His research emphasizes ombining data from living and fossil organisms to study the origins and fates of lineages and adaptations, to develop an understanding of the underlying dynamics of speciation and extinction that could lead to a general theory of evolutionary novelty. He is interested in the way evolutionary patterns are shaped by the alternation of extinction regimes, with rare but influential mass extinctions driving unexpected evoutionary shifts.
Johanson, Don: A paleontologist and founder of the Institute for Human Origins. Johanson discovered Lucy (at that time the oldest, most complete hominid skeleton known) in 1974, and the following year unearthed the fossilized remains of 13 early hominids in Ethiopia. He is the author of several popular books on human origins.
Johnson, Jerry: Johnson's research interests focus on the interactions and evolutionary relationships of amphibian and reptilian species of tropical American and Mexican desert ecosystems. Johnson specializes in field research in places such as Yucatan, Jalisco, Zacatecas, and Chiapas, Mexico. He has done research on the biochemical analysis of rattlesnake venom using immunological techniques, snake ecology, and lizard ecology.
Johnston, Victor: Professor of biopsychology at New Mexico State University in Las Cruces. His research interests include the evolution of consciousness and perceptions of beauty. He is the author of Why We Feel: The Science of Human Emotions.