Evolution explains a number of fascinating facts about the world we live in and the strange creatures to be found here. From why the Cameroonian horror frog can break its own bones to produce claws, to why the horned lizard shoots blood through its eyes. Science has an answer to the strangest phenomenon, but there are still a quite a few natural quandaries that leave some of us totally stumped. For example: why would a male animal have prominent features only required by the female of the species? Can this strange biological quirk be explained by science? Why do men and women both have breasts?
First of all, why do human beings, male and female, have two nipples? Why not one nipple? Or three nipples? Well, it seems that the general biological rule of thumb is that a mammal ordinarily has twice as many nipples as it needs to feed its offspring. Cows often give birth to twins so they have 4 nipples, a small dog will normally have 8 nipples and a large hound has 10, because a normal litter is usually around 4 to 5 puppies. Humans normally have 1 baby at a time so it therefore follows that we have 2 nipples. Most but not all animals have an even number of nipples; the opossum, for example, has 13 nipples, blowing the theory of dividable nipple numbers out of the proverbial biological window – but let’s overlook that for the time being. The pressing question is why do male animals, who we assume cannot usually produce milk, also have nipples, or teats?
It all starts in the womb. While men and women eventually grow and develop to have separate features, they do begin from the same genetic blueprint. During those first few weeks inside the womb, both men and women look pretty much the same, with shared features including, you guessed it, nipples. After about six weeks, a Y chromosome gene kicks in some changes in the fetus, including the development of the testes in the male, and after two more weeks, the genetic activity of cells in the genitals and brain begin to change but, by that stage, the nipples are here to stay with both males and females.
But human growth and development scientists can’t tell us why exactly men keep this vestigial body part that serves no evolutionary purpose to the male of the species. Well, at least most of the time. The vast majority of men don’t lactate but some do; Due to hormone imbalances, some men have been known to be the unwilling bearers of milk and in rare occasion may actually be able to feed their offspring through chance. And why shouldn’t this be so? Men do have milk ducts and some mammary tissue and through excessive breast pumping and nipple stimulation, a new movement of men, known collectively as Milkmen, are also able to manipulate their manboobs into suitable suckling appendages.
In a study called “Male Lactation,” Professor Patty Macadam of the Department of Anthropology at the University of Toronto, observed the following.
“It is possible and has been observed in animals and humans. In 1992 Dayak fruit bats were captured from a rain forest in the Krau Game Reserve, Pahang Malaysia. Of the 10 mature males captured, each had functional mammary glands from which small amounts of milk were expressed. A breast is a breast. Male lactation is physiologically possible and according to Dr. Robert Greenblatt, production in males can be stimulated by simply letting a baby suckle for several weeks.”
The phenomenon of men breastfeeding at will was explored in the 1978 book The Tender Gift by Dana Raphael and subsequently a small movement of Milkmen evolved. But this Milkman phenomenon doesn’t occur nearly enough to make it a biological necessity for men to have a pair of nipples and so it seems rather to be an offshoot of and utilization of our quirky design rather than biological intention.
So if men weren’t supposed to have nipples, then why wouldn’t nature take its Darwinian course and over the years, men would lose the attribute of nipples through some kind of natural selection process? Scientists counter that by saying “There’s no real metabolic cost to having nipples,” and therefore it is not exactly an evolutionary priority to get rid of them. Women do not refuse to mate with men who have nipples so why would Mother Nature decide to be rid of them? Natural selection is not hovering around constantly with the aim to get rid of things we don’t need. Quite simply, the presence of man’s nipples is hardly a threat to the survival of the species. Nipples on men aren’t really doing much harm. And perhaps as the world becomes a more liberal place to live, and with same-sex marriages now becoming more common, we are entering an age where two males are biologically adapted physically to adopt and nurture a child naturally using the nipples that they were born with – perhaps this is the reason behind the design.
What we need to remember is that natural science evolution is never neat and tidy. Quite the opposite is true. Nature is messy and unpredictable with strange quirks, but usually nature has some long term solid plans including men with nipples.
So, why do you think men have nipples? Let us know in the comments.