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.
American Journal of Physical Anthropology of biology and medicine, along with the "American Journal of Botany", "British Medical Journal", "Journal of Paleontology", "Journal of the American Medical Association", "Journal of Zoology", "Nature", "New England Journal of Medicine", "Proceedings of the National Academy of Sciences", and "Science". According to the Journal Citation Reports, its 2011 impact factor is 2.824, ranking it 6th out of 79 in the category "Anthropology" and 23rd out of 45 in the category "Evolutionary Biology". Additionally, the journal has earned the most citations in the category "Anthropology" each year for over a decade. The Yearbook of Physical Anthropology is an annual peer-reviewed