> Sorry, what? Neanderthal women didn’t have four breasts. There’s no claims of that anywhere that I can find. In fact, a google search for “neanderthal four breasts” returns your post as the first hit. Where did you get this idea from?
I'd post a pic, but I'd get banned for sure. :)
Polymazia is of much more frequent occurrence than is supposed. Julia, the mother of Alexander Severus, was surnamed "Mammea" because she had supernumerary breasts. Anne Boleyn, the unfortunate wife of Henry VIII of England, was reputed to have had six toes, six fingers, and three breasts. Lynceus says that in his time there existed a Roman woman with four mammae, very beautiful in contour, arranged in two lines, regularly, one above the other, and all giving milk in abundance. Rubens has pictured a woman with four breasts; the painting may be seen in the Louvre in Paris.
There was a young and wealthy heiress who addressed herself to the ancient faculty at Tubingen, asking, as she displayed four mammary, whether, should she marry, she would have three or four children at a birth. This was a belief with which some of her elder matron friends had inspired her, and which she held as a hindrance to marriage.
Leichtenstern, who has collected 70 cases of polymazia in females and 22 in males, thinks that accessory breasts or nipples are due to atavism, and that our most remote inferiorly organized ancestors had many breasts, but that by constantly bearing but one child, from being polymastic, females have gradually become bimastic. Some of the older philosophers contended that by the presence of two breasts woman was originally intended to bear two children.
http://www.enotalone.com/article/14881.html
Wiki says, in answer to the question that: "The nipples and glands can occur anywhere along the two milk lines, two roughly-parallel lines along the ventral aspect of the body. In general most mammals develop mammary glands in pairs along these lines, with a number approximating the number of young typically birthed at a time."
For Neanderthal to have, with certainty, had "twins" they'd had to have had a lot of triplets and quadruplets since "twinning" is necessarily a biological minimum.
The Twa' people in Africa almost always have twins ~ and at the same time they are a pygmy people much like our very own San ancestors.
It's possible that during extensive migration humans lost the capacity for widespread twinning where the more settled Twa have retained it, as did the Neanderthal.