There seems to be a logical explanation about why women have nipples - for babies. But why do men's bodies retain what appears to be redundant body parts? The Darwinian natural selection process would seem to dictate that male nipples really should not be there. So what's the deal? Why do men have nipples?
The answer is that as embryos men and women have similar tissues and body parts. If anything the embryo follows a 'female template'. That is why nipples are present in both sexes. It is the effect of the genes, the Y chromosome and the hormone testosterone that brings about the changes and masculinises the embryo. Testosterone promotes the growth of the penis and testicles. Because nipples are there before this process begins the nipples stay!

Nipples and breast tissue have no function as such except for perhaps protecting the heart and lungs from injury.

Male Breasts Can Produce Milk and Get Breast Cancer
A certain level of the female hormone estrogen is present in all men. If, as a result of disease or a condition affecting hormones, breast tissue in men can grow (gynecomastia- abnormal enlargement of breasts,) and men can produce milk.

Gynacomastia is more commonly seen in adolescence, a period in development when hormones fluctuate a lot. It is also seen in some men with liver disease and sometimes in alcoholics.

Men can get breast cancer as well as women.

some men actually produce milk in their breasts... true

......

you mean my ex could have be breast feeding all that time when our children were babies.. that just

my dad wouldnt have liked me sukin his nippy.....

Yup. We all start out female until a certain point in gestation. Men can produce milk and it can also sometimes be seen in newborn males. The estrogen in the mothers blood during gestation soemtimes stays in the child until it works it's way out of the body. And if the mother is breat feeding this can be a cause as well..........my son produced milk and I was devastated until the Dr explained it to me. It stopped a week later. Hmmm, something to think about.

from another site ... an interesting read on male lactation

I first became interested in male lactation in 1978 after reading Dana Raphael's book, The Tender Gift: Breastfeeding. Although Raphael only dealt with the subject briefly, she did say that men can and have produced milk after stimulating their nipples.

While my husband David had no interest in nursing our son, we both were intrigued with the idea. We had just had our first unassisted homebirth and were excited about applying our positive thinking techniques to other aspects of our lives. Although Raphael had written about milk production through nipple stimulation, perhaps, we thought, David could do it simply through suggestion. He began telling himself that he would lactate, and within a week, one of his breasts swelled up and milk began dripping out. When we excitedly showed my father (a physician) David's breast he said, "Obviously there's something physiologically wrong with David." The fact that David had willed himself to do this, did not impress him. We knew, however, that this was yet another example of the power of the mind.

Still, we were not ready for David to actually breastfeed our baby. First of all, there was no need for it. I was doing just fine on my own. But more importantly, he simply had no desire to do it. After he discovered that his body had indeed been responsive to his thoughts, he suggested to himself that the lactation would stop, and within a week his breast returned to normal. The experiment had been a success.

We didn't give it much thought after that until years later when I came across a short article called "Male Lactation" by Professor Patty Stuart Macadam of the Department of Anthropology at the University of Toronto (Compleat Mother, Fall, 1996, Volume 43).

It is possible, and has been observed in animals and humans. In 1992, 18 Dayak fruit bats were captured from a rainforest 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 letting a baby suckle for several weeks. Indeed some human males secrete milk at birth and at puberty.Historically, male lactation was noted by the German explorer Alexander Freiherr von Humboldt prior to 1859, who wrote of a 32-year-old man who breastfed his child for five months. It was also observed in a 55-year-old Baltimore man who had been the wetnurse of the children of his mistress.
My interest in male lactation was piqued again when I recently received the following letter from a friend of mine.

I knew these two wonderful guys, very dear friends of mine for years. A mutual acquaintance of ours was pregnant, unplanned, and did not want to do the whole "adoption thing" so when the guys approached her about taking the baby, they just proceeded as if it had been a planned surrogate pregnancy. The guys were adamant that the baby should get breastmilk. So when she was in her 7th month we bought a really good quality breastpump and Ian started pumping, every 2 hours during the day and once during the night. He was wonderful about it! He used an SNS (supplimental nursing system) after she was born, with donated milk from several friends who were nursing. He was making milk but not a full supply. By the time the baby was 12 weeks old he was making a full milk supply! He stayed at home with the baby (he was a massage therapist) and nursed her exclusively until she was 8 months old!! I don't think many people outside their intimate circle knew about it, I'm sure folks would have had a fit if they'd known...but I thought it was wonderful!
While reading my friend's letter, I suddenly remembered my mother telling me years ago that as an infant I once tried to nurse on my father. I laughed about it at the time, yet I'm sure it is a fairly common occurrence. Babies want to be loved, nursed, and nurtured. The gender of the person doing it is not important.

On the other hand, I think it is safe to say that women are better suited to breastfeeding than men are. They generally produce milk soon after birth, with little or no nipple stimulation. If a mother is completely out of the picture, however, as in the case of adoption, or a mother goes back to work and a baby is left in the care of its father, for some families male breastfeeding might be an acceptable alternative to formula bottles and pacifiers.

For those who claim male lactation is "unnatural," I would have to ask: how natural is canned formula from Nestle' or pacifiers made from petrolium byproducts? If milk production in men were truly unnatural, it wouldn't exist. The fact that it does, leads me to believe that perhaps male lactation is simply nature's back-up system. In any case, it's an interesting phenomenon.