ABSTRACT

Human beings have colonized a wide range of environments across the planet, adapting in both biological and cultural ways. As a result, the allelic frequency of particular genes varies between groups that have been living for long periods of time in particular geographical areas. However, this kind of variation does not tend to follow culturally constructed racial lines (see selections 13, 14, 15, 40, 42). At the same time, growth and development depend on interlocking social, economic, cultural, and biological influences such that vast differences in morphology can arise between individuals with a shared genetic constitution. For example, body proportions and height can change dramatically in a single generation due to altered living conditions affecting factors such as nutrition, infectious disease, and psychophysical stress (see selection 48; Mascie-Taylor and Bogin 1995; Ruff 2002). The following selections focus on the remarkable variability and plasticity of human beings.