Eye color for a plausible argument stating that some eyes can or do change, based on chemical reactions and hormonal changes within the body. Studies on Caucasian twins, both fraternal and identical, have shown that eye color over time can be subject to change, and major demelanization of the iris may also be genetically determined. Most eye-color changes have been observed or reported in the Caucasian population with hazel and amber eyes. Carleton Coon created a chart by the original Martin scale. The numbering is reversed on the scale below in the (later) Martin–Schultz scale, which is (still) used in physical anthropology.
Applied anthropology "the study of humans, past and present. To understand the full sweep and complexity of cultures across all of human history, anthropology draws and builds upon knowledge from the social and biological sciences as well as the humanities and physical sciences." Thus, the field is divided into four subareas: sociocultural anthropology, biological (or physical) anthropology, archaeology, and linguistic anthropology. Because a central tenet of the anthropological field is the application of shared knowledge and research about humans across the world, an anthropologist who specializes in any of these areas and enacts research into direct action and/or policy can be deemed