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.
Anthropology tend to use different methodologies and techniques. European countries with overseas colonies tended to practice more ethnology (a term coined and defined by Adam F. Kollár in 1783). It is sometimes referred to as sociocultural anthropology in the parts of the world that were influenced by the European tradition. Anthropology is a global discipline involving humanities, social sciences and natural sciences. Anthropology builds upon knowledge from natural sciences, including the discoveries about the origin and evolution of "Homo sapiens", human physical traits, human behavior, the variations among different groups of humans, how the evolutionary past of "Homo sapiens" has influenced