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TODAY WE MEN ARE EXPECTED TO SHARE IN THE care of our children. We have no excuse not to, of course, since we are perfectly capable of doing practically anything our wives can do. And so, when my twin sons were born, I duly learned to change diapers, clean up vomit, and perform the other tasks that come with parenthood.
The one thing I was excused from doing was nursing my infants. It was a visibly tiring task for my wife, and friends kidded me that I should get hormone injections and share the burden. Yet cruel biological facts appear to confront those who would bring sexual equality to this last bastion of female privilege or male copout. Males--and not just human males, mind you--seemingly lack the anatomic equipment, the priming experience of pregnancy, and the hormones necessary for lactation. Until last year, males of not a single one of the world's 4,500 mammal species were suspected of lactating under normal conditions.
Brace yourselves, guys. Science is demolishing your last excuses. We've known for some time that many male mammals, including some men, can undergo breast development and lactate under special conditions. We've also known that many otherwise perfectly normal male domesticated goats, with normal testes and the proven ability to inseminate females, surprise their owners (and probably themselves) by spontaneously growing udders and secreting milk. Now we know that at least one wild mammal engages in similarly odd behavior: just last year, spontaneous male lactation was reported in the Dayak fruit bat of Malaysia. Ten adult males, captured alive, proved to have mammary glands distended with milk.
Lactation, then, lies within a male mammal's physiological reach. Yet it's not part of our normal human repertoire, nor the normal repertoire of any other mammalian males--except, intriguingly, for the Dayak fruit bat. Why, then, since natural selection evidently could have made us men lactate, didn't it? Might it reprogram us in the future? Might male lactation, now a fascinating theoretical problem at the interface of physiology and evolutionary biology, soon advance from the realm of theory into practice?
Let's start with the facts. Of the 23 pairs of human chromosomes, 22, and the genes that they carry, are the same in men as in women....