The ratio of the size of the ring finger to the middle finger is a good measure of exposure to androgens during fetal growth. Men with relatively longer ring fingers are exposed to more male hormones before birth, and tend to be more sexually active and aggressive than men with shorter ring fingers.
A study of Neanderthal skeletons from Liverpool University in Great Britain found that the ancient cave man was horny and sexually active. Our human ancestors who lived over 4 million years ago were extremely promiscuous, while more modern humans became more sexually exclusive. This theory is highly controversial, because sexual promiscuity in ancient human ancestors would have broadened the gene pool, which might have made them a more successful species. Many women refer to men as Neanderthals, so perhaps the theory is correct. (British Journal Proceedings of the Royal Society B, published online November 20, 2010)