In mammals, including humans, the main purpose of the nipple is to help nurse the offspring. This function is so important to organisms like us that it is considered one of our defining features. Yet, men and other male mammals are generally incapable of breastfeeding babies even though they have nipples. So why do men have nipples? and do they serve any purpose? Let’s find out!

Why Do Men Have Nipples?

According to experts, in the early stages of embryonic development, all human embryos look the same. Sure, some may have the XY chromosome pair while others have the XX chromosome pair, but this does not seem to make a difference in their respective developments until a bit later. Essentially, then, all human embryos start their lives with the potential to turn into either of the biological sexes. This then means that both male and female embryos develop rudimentary forms of breasts and nipples in the first few weeks. But soon after, the Y chromosome (if an embryo contains it) activates an essential gene on it called the SRY gene.

This gene is critical to the development of male characteristics in the embryo. It acts as a transcription factor (binding with specific sections of DNA and controlling certain genes) and provides instructions to produce the sex-determining region Y protein. This protein is involved in the process of male sex development and ensures that male embryos form testicles instead of a uterus and fallopian tubes. However, there’s not much it can do about features that have already been developed. Consequently, the male embryo simply retains the breast and nipple tissues it possesses.

Why hasn’t evolution resulted in the absence of this trait in men?

The fact is, that evolution and natural selection are more complex than we realize. This then means that these processes do not always work with a specific goal in view. In nature, it is common to find organisms that are far from perfectly adapted. This can be seen in the case of sharks since they do not have gas bladders to control their buoyancy despite being aquatic organisms. Yet, it would be wrong to say that these creatures have not been subjected to evolution or natural selection.

Natural selection, therefore, is a purely random process, and it is hard to guarantee that it will eventually remove all traits that do not serve a purpose. As a result, many organs, such as the males’ nipples, continue to exist despite their apparent lack of function. Also, having nipples does not seem to actively hurt men. So, even if evolution were to get rid of this trait, it is likely not going to be a priority.

Do male nipples actually serve a purpose?

Before you leave here thinking male nipples are pointless, we’d like to set the record straight! Yes, male nipples typically do not have a role to play in breastfeeding the young ones, but they do serve as erogenous zones in humans. Studies have shown that nipples respond to sexual stimulation in both men and women. According to one such study, about half of the male test subjects reported that stimulation of the nipples caused or enhanced their sexual arousal.

Of course, this number was higher in the female test subjects, with around 80 percent of them saying it caused or enhanced their sexual arousal. But it still proves that male nipples have at least some function attributed to them. In another rare occurrence, a 1990 study reported that a heterosexual man actually requested the enlargement of his breasts and nipples. His reasoning was that it caused him great sexual excitement to stimulate those parts of his body and he felt incomplete without them.

Can men get breast cancer?

Yes, men, too, can get breast cancer. According to the Centers for Disease Control and Prevention (CDC), one out of every 100 breast cancer patients in the US is a man. Such patients, although rare, are diagnosed with similar forms of cancer as those found in women. These include invasive ductal carcinoma, which begins in the ducts and spreads outside; invasive lobular carcinoma, which starts in the lobules of the breast and moves on to other parts of the tissue; and ductal carcinoma in situ, in which cancer cells are found lining the ducts of the breast but have not spread yet.

Experts suggest that to stay ahead of this disease, men should watch out for symptoms like swelling or lumps, redness, irritation, nipple discharge, or pain in the general area of the nipples. However, these symptoms do not necessarily suggest cancer and must be thoroughly evaluated by a doctor. Men are also at higher risk of getting breast cancer with progressing age, a family history of the disease, or certain genetic conditions. But don’t let that alarm you too much! If diagnosed early, men with this form of cancer have a good chance of recovery.

What other conditions should men watch out for?

Men, despite having less functional breast and nipple tissues than women, are afflicted with a slew of disorders in these body parts. We’ve had a look at breast cancer, but there’s another form of rare cancer that can be diagnosed in men. This disease, called “Paget’s disease” of the breast or nipple, is cancer that typically affects the nipple and the darker skin around it called the “areola.” Like breast cancer, this is more commonly diagnosed in women but men can also be affected. The nature of this disease is also similar to female breast cancer.

Experts have put forth some theories on the origin and development of Paget’s disease. One theory suggests that cancer cells from a tumor within the breast tissue travel through the ducts to the nipple and areola, affecting the tissue there. This could be why Paget’s disease of the breast and tumors inside the same breast are often found together.

A second theory states that the cancer cells in the nipple or areola may even develop independently, without a tumor in the same breast. But not all conditions affecting male breast tissues are as serious as cancer. Sometimes, a simple imbalance in testosterone can lead to disorders, like gynecomastia, where men develop larger breasts.