While there is a reasonable biological explanation for why women have nipples to feed their babies, their role in men remains less clear.
Darwin's theory of natural selection would seem to dictate that male nipples have no real purpose and, as such, they should have already been derived from the human species. Of course not, and this has to do with the basics of how a person begins to develop in the womb.
The answer is simpler than you think. During embryogenesis (the development of the embryo after fertilization), both females and males start, so to speak, from the same genetic base.
Only in the second half of the first eight weeks will sex genes, called X and Y chromosomes, determine whether a baby is male or female. The Y chromosome is the one that distinguishes men (who will have one X and one Y chromosome) from women (who will have two X chromosomes).
During the first four to five weeks of pregnancy, there is no difference between the sexes, even if the embryonic cells continue to divide and specialize. At this stage, the nipples are already developing.
It is not until the sixth or seventh week that the Y chromosome will cause changes (via the SRY gene) that will lead to the development of testes and males .
In contrast, female embryos that are not influenced by the Y chromosome undergo breast cell changes, beginning with the development of a fossa in the center of each nipple. This fossa gradually forms a depression that connects to the lactiferous (milk producing) duct.
While this happens to some extent in men, it is much less deep and developed.
Male nipple function
Although male nipples are sometimes thought of as vestiges, meaning that they have lost their function throughout evolution (much like the appendix or wisdom teeth), this is largely incorrect. They can be more accurately described as fetal remains, but even this suggests that they have no real purpose.
The nipples, in fact, contain many nerves that function as the main stimulating organ in both men and women. Therefore , it can be seen as a secondary sexual characteristic along with pubic hair, enlarged breasts, and enlarged hips in women. as well as facial hair and Adam's apple in men.
The male nipple is no less sensitive than the female one and can contribute significantly to sexual arousal when stimulated.
That said, the nerve network of the male nipple is much denser, which means that the sensory response tends to be more subtle. This response in both men and women appears to be unique to the human species.
Male nipple abnormalities
There are characteristics associated with a woman's breast and nipple that can also show abnormally on a man's breast and nipple. Some of them are the result of hormonal dysregulation, while others can be caused by genetics.
Although men do not breastfeed under normal circumstances, men's breasts can produce milk if they are under the influence of the hormone prolactin.
A condition known as male galactorrhea is often the result of a drug or medical condition causing a decrease in male hormones (primarily testosterone) and an associative increase in female hormones .
An example of this is Motilium (domperidone), which not only treats lactation problems in women, but can also be used in men to treat nausea, vomiting, stomach paresis, and Parkinson's disease.
Other causes include malnutrition, pituitary gland disease, hypothyroidism (decreased thyroid function), and frequent nipple stimulation.
Gynecomastia is the enlargement of the male breasts that generally occurs in older men, as testosterone levels gradually decline with age. In addition to the general swelling of the breast tissue, gynecomastia can cause enlargement of the nipples and surrounding areolas .
Gynecomastia can also affect boys and younger men for a number of reasons. In some cases, the condition will be temporary, especially in male adolescents during puberty.
Other common reasons include:
- Tumor of the adrenal or pituitary gland
- Use of anabolic steroids
- Cancer chemotherapy
- Renal insufficiency
- Prostate medications such as propecia (finasteride) and aldactone (spironolactone)
- Tricyclic antidepressants
Gynecomastia is associated with an increased risk of breast cancer in men. Breast cancer in men, although rare, is most often detected by the formation of a hard lump under the nipple and areola.
Frequently asked questions
Generally, the nipples of both sexes are practically indistinguishable until puberty, during which time the breasts and nipples of both sexes undergo noticeable changes. As a result, male nipples tend to be smaller than female ones; there are also fewer differences between male nipples than female nipples.
Some biological males can lactate , most often as a result of certain diseases, such as pituitary tumors , or drugs that stimulate prolactin, the hormone responsible for milk production. And there have been cases where men were able to deliberately stimulate lactation to breastfeed, although how this could be accomplished remains controversial.
For about half of men, the nipples are an important erogenous zone. Some experts suspect that this means that male nipples have an evolutionary function, playing a role in the desire to mate and reproduce. Some research suggests that nipple stimulation activates areas of the brain associated with genital arousal .