Iodine is essential for modern humans and may have been essential for Neand
ertals as well. Today about 30 percent of the world's population is at risk
of iodine deficiency disorders (IDD),750 million people suffer from goiter
, 43 million have IDD-related brain damage and mental retardation, and 5.7
million are afflicted by cretinism, the most severe form of IDD. Distinctiv
e Neandertal skeletal traits are identical to those of modern humans who su
ffer from cretinism. Cro-Magnon Venus figurines also exhibit distinctive tr
aits associated with cretinism among modern humans. This new evidence, coup
led with recent mitochondrial DNA findings, suggests that a single genetic
alteration, which improved the ability of the thyroid gland to extract and
utilize iodine, may account for differences between Neandertals and modern
humans. Late Pleistocene human evolution, consequently, may be explained by
several alternative interpretations involving iodine pathology and/or biol
ogical adaptation. Speciation may have resulted from the geographical isola
tion of inland populations.