Pub. date: 2006 | Online Pub. Date: September 15, 2007 | DOI: 10.4135/9781412952453 | Print ISBN: 9780761930297 | Online ISBN: 9781412952453| Publisher:SAGE Publications, Inc.About this encyclopedia
Penelope A. McLorg
Clines are gradations in biological features over geographic space. They refer to continuous degrees of difference in either phenotype or genotype across or within human populations. A given cline consists of the gradient in frequency of a single trait over space. This graded change is often associated with a gradually changing environmental factor. Thus, gradients in the appearance or function of a trait represented by a cline can correspond with graded alterations in the environment. Clines are useful to biological, medical, and other anthropologists interested in depicting and analyzing human variation. When a cline is graphically portrayed, portions of the distribution of the trait that have the same value are connected by a line. On either side of the line appear other lines representing progressively greater and lesser frequency of the trait. Thus, the graph of the cline resembles a weather map, with bands of varying temperature or pressure occurring ...