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.
Molecular anthropology a limited scale up to the late 1990s when the staff at the Max Planck Institute shocked the anthropology world by sequencing DNA from an estimated 40,000-year-old Neanderthal. The result of that experiment is that the differences between humans living in Europe, many of which were derived from haplogroup H (CRS), Neandertals branched from humans more than 300,000 years before haplogroup H reached Europe. While the mtDNA and other studies continued to support a unique recent African origin, this new study basically answered critiques from the Neandertal side. Significant progress has been made in genomic sequencing since Ingman and colleague