But oxytocin release has other effects, too. So do men really want women with big boobs? It's biological and deeply engrained in our brain. In a chapter in the book "Breastfeeding: Biocultural Perspectives" Aldine de Gruyter, , cultural anthropologist Katherine Dettwyler describes telling friends in Mali about sexual foreplay involving breasts and getting responses ranging from "bemused to horrified. But visit any of the zillion free porn-sampler sites lobstertube. This bond is not only the most beautiful of all social bonds, it can also be the most enduring, lasting a lifetime. Some researchers think that sexual interest in breasts simply hijacks the breastfeeding circuitry and uses it for another purpose. We are also the only species in which males caress, massage and even orally stimulate the female breasts during foreplay and sex. There, the signals trigger the release of a neurochemical called oxytocin from the brain's hypothalamus. The first modern bra was patented in —two handkerchiefs sewn together with straps made of ribbon. As bra size increased, so did the number of men who approached them. Sexual strategy may be reflected in sociosexuality, which is defined as a willingness to engage in sex without commitment. A study in the Proceedings of the Royal Society B even found that women with large breasts have higher levels of the hormone estradiol mid-cycle, which could increase fertility. They should thus be strongly interested in cues that signal, in a prospective mate, fertility and health, but also willing to engage in short-term mating. In other words, men can make themselves more desirable by stimulating a woman's breasts during foreplay and sex.