Similar but Different

Individual biological variation and its sources are described. The role of genes and environmental factors in the formation of variation is explained, basic methods of measuring variation given and examples of variation presented. Distribution of human variation within and between populations is discussed with the conclusion that the concept of “race” is not applicable to humans. Differences between people from various geographic areas are small, not sufficient for meaningful separation of humanity into distinct subunits comparable with breeds of some animals. The process of microevolution as a continuous alteration of variation ranges is exemplified by recent changes in the prevalence of genetic defects, anatomical variations (e.g. spina bifida occulta), reduction of human brain size by about 10% in the last few thousand years, shortening of body height when hunters-gatherers adopted agriculture and subsequent increase in body height in post-industrialised world, and by alterations of head shape in some nations in the last few hundred years.

Keywords: Albinism, Microevolution, Nutritional status, Phenylketonuria, Race, Spina bifida occulta, Variance.