This mostly affects adolescent boys and usually resolves on its own, although it can persist in as many as one in 10 men. In these cases, it can be associated with depression, anxiety, disordered eating, body image problems and reduced self-esteem.
Unusually, men can develop breast cancer and it can have serious consequences. Only 0. However, lower awareness of the disease in men means it is more likely to be at an advanced stage when diagnosed. Read more: Breast cancer campaigns might be pink, but men get it too. Although, this is unlikely to distract the celebrity gossip columnists from their selective obsession with this part of the female anatomy.
Edition: Available editions United Kingdom. Become an author Sign up as a reader Sign in. Men have nipples because of a quirk in how embryos develop.
Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. While there is a reasonable biological explanation as to why women have nipples —to feed babies—their function in men remains less clear.
The Darwinian theory of natural selection would seem to dictate that male nipples serve no real purpose and, as such, should have been bred out of the human species by now.
Of course, they have not, and this has to do with the foundations of how a human begins developing in utero. The answer is simpler than you think.
During embryogenesis the development of an embryo after fertilization , females and males will both start from the same genetic base, so to speak. It is only in the latter part of the first eight weeks that the sex genes—called the X and Y chromosome—will dictate whether the baby will be female or male. The Y chromosome is the one that differentiates males who will have one X and one Y chromosome from females who will have two X chromosomes.
During the first four to five weeks of gestation, there is no differentiation between sexes even as the embryonic cells continue to divide and specialize. At this point, nipples are already developing.
It is only by weeks six or seven that the Y chromosome will induce changes by way of the SRY gene that lead to the development of the testes and the male sex. By contrast, female embryos, which are not under the influence of the Y chromosome, will undergo changes in the mammary cells, starting with the development of a pit at the center of each nipple.
This pit will gradually form a depression that connects to a lactiferous milk-producing duct. While this happens to some degree in males, it is far less profound and developed. While male nipples are sometimes thought to be vestigial—meaning that they have become functionless in the course of evolution much like the appendix or wisdom teeth —that is largely untrue. They may be more accurately described as remnants of fetal development, but even that suggests they serve no real purpose.
The nipple, in fact, contains a dense supply of nerves that function as a major stimulatory organ in both men and women. The male nipple is no less sensitive than the female nipple and can contribute significantly to sexual arousal when stimulated. With that being said, the nerve network in the male nipple is much denser, meaning that sensory response tends to be more discreet. Which begs the question: why do men have nipples in the first place?
So why do men have them? In other words, before gender is determined, the embryo develops breasts and then nipples, Dr. Laitman says, and they stay. There are some exceptions if someone suffers from athelia, a rare condition where an embryo doesn't develop one or both of their nipples. Laitman says. Some men can develop breast tissue during puberty or later if they suffer from gynecomastia , a condition where male breast tissue is overdeveloped.
Since both men and women have breast tissue, regardless of how much or little they have, male nipples can occasionally have discharge. In females, they are essential for delivering life-sustaining breast milk to newborns. In men, they serve, well, no apparent purpose.
Few scientific tenets are as certain as this one. This tempting idea goes back as far as Erasmus Darwin, the grandfather of Charles Darwin, who considered adaptivity in his book Zoonomia; Or, the Laws of Organic Life , an early treatise on evolution.
As evolutionary theory progressed through another Darwin and beyond, biologists refined their understanding of its mechanisms. Gould and Lewontin contend that other factors besides natural selection control the operation of evolution, one being simply the lack of selective pressure against a trait.
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