A team of researchers at the University of Queensland in Australia published a new study on Tuesday, and the results challenge long-held assumptions about a rather personal topic — the size of women's nipples. And men's nipples, as well. While a long-held belief holds that bigger nipples on women are a disadvantage in terms of human evolution, the study published in the scientific journal Adaptive Human Behavior and Physiology debunks that belief.
In fact, nipple size means essentially nothing for evolution, the study's authors say. But the study may also offer insights into the function of the human orgasm as well, the Australian study's lead researcher said — based on the difference in size between the male penis and female clitoris, according to a summary of the study published this week by Science Daily.
Biologists commonly believe that the lack of variation in the size of a human organ or body part indicates that the specific, uniform size must convey an advantage for survival — the basis of the evolutionary theory of natural selection, which holds that nature will "select" certain characteristics because they are better for the survival of the species.
According to an explanation by the University of California at Berkeley, "If you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome. It is as simple as that." When it comes to nipple size, that would mean that women with the most ideally-sized nipples for breastfeeding will produce the most offspring. But is there such a thing as an ideal nipple size?
The researchers say no. They optically scanned and measured the nipple of 63 volunteers, accounting for variations in chest size, bustline measurements, and even room temperature. They found that on average, male nipples measured at 36 percent the size of female nipples on average — but that female nipples showed far greater variation in sizes.
Under current evolutionary theory, the result should have been exactly the opposite. The feature that showed greater variation should be the non-functional one. Women's nipples, which are necessary for feeding offspring, should show less variation than men's nipples in size under the theory of natural selection.
"Therefore, the finding that females nipples are highly variable discredits previous studies that indicate variation in a specific feature indicates a lack of functionality," said lead researcher Ashleigh Kelly.
So what does this mean for penis size — and orgasms? According to the Science Daily report, previous studies have shown that the size of the female clitoris shows greater variation than male penis size. As a result, evolutionary biologists have concluded that orgasms in women serve no function, and only exist as a useless by-product of the male orgasm.
"Based on the current findings, Kelly says that this evidence should be disregarded because the analogy of male and female nipples shows the opposite effect," the Science Daily report explains. The findings would also indicate that the lesser variation in penis size also carries no significance, and one particular size of penis is no better than any other — at least in terms of human evolution.