One might wonder why human males have nipples, what purpose they serve, and whether this is unique to humans. The answer to these questions is certainly intriguing.
This question was even considered by Charles Darwin's great-grandfather, Erasmus Darwin, who was a physician, philosopher, and inventor. He discussed the futility of nipples in male animals in his book "Zonomia, or the Laws of Organic Life," published in 1794.
Men have nipples for a simple evolutionary reason, and they are not exclusive to humans, according to scientists, who point out that men have nipples because they develop before the sex of the fetus is determined.
The question of the role of nipples in men has long been a subject of debate. Women need nipples to nurse their babies, while men generally consider them unnecessary. It is now believed that male nipples exist simply because they do not interfere with bodily functions. During evolution, traits that do not affect the survival of a species often persist; for example, the eyes of blind deep-sea fish, which have always relied on other senses.
Male nipples are not a natural anomaly or a genetic predisposition, although this view is prevalent in some circles. The whole issue is related to how the embryo develops.
In the womb, all human embryos follow the same genetic blueprint during the first few weeks, meaning they develop similarly. The development of nipples and breast tissue begins very early, around the fourth to sixth week of pregnancy. Around the seventh week, the SRY gene on the Y chromosome, if present, is activated, stimulating the development of male reproductive organs. If the Y chromosome is present, hormones, specifically testosterone, begin to be produced, further stimulating the development of male sexual characteristics. However, at this stage, the nipples are already present; they don't disappear because their formation began long before this hormonal "selection." This is simply a natural consequence of everyone starting from the same basic plan.
In other words, since nipple development is already underway before the genetic shift, it continues in both sexes. In males, this results in non-functional nipples, which are considered an "evolutionary outcome" of the females' need for them.
From an evolutionary perspective, male nipples are considered "harmless." Because they do not hinder survival or reproduction, there has been no significant "selective pressure" to remove them, as getting rid of them would require a radical redesign of the early development plan.
Experts point out that there are common misconceptions that embryos start as females and then become males, while the more accurate view is that all embryos start from a common, gender-neutral plan.
As for the function of male nipples, scientists say that although they do not serve a reproductive function, they are not entirely without function. They are an area rich in nerve endings and can be, in both men and women, an "erogenous zone" that helps in achieving orgasm.
Nipples are not only found in human males, but also in many other male mammals. However, in most species, unlike humans, they are not as highly developed as in females and do not serve a significant function. For example, males of some mammals, such as mice and rats, lack nipples because the tissue regresses during embryonic development.
Another fascinating and surprising secret is that some women may develop extra nipples before giving birth. These nipples come in various shapes and sizes, sometimes appearing as small pink or brown spots or birthmarks, and usually do not require treatment unless they cause pain or discomfort.
Experts point out that since these extra nipples are often small and underdeveloped, and may look like freckles or moles, many women are unaware of their existence.
In other words, the significant hormonal changes during pregnancy cause the development of additional nipples that enlarge and become more prominent, just like normal nipples. These extra nipples may also become swollen, painful, or even produce milk after childbirth. Doctors say this condition is relatively common, affecting between 1% and 5% of women—a figure that reflects the complexity and wonder of the human body, which continues to reveal its secrets day after day.
