The weirdness of male lactation

When our first child was under way, we had a few interesting lunch discussions with some friends/colleagues over this one. Recently it resurfaced but under a very different aspect.

Weird biology

One of the reasons I love biology is that it is the realm of the weird, wonderful and bizarre. For every rule in biology there is usually a weird, obscure exception (e.g. flying or land-walking fish, egg-laying mammals, herbivorous spiders, gliding snakes, diving lizards, ...). Also in general every bizarre thing one can think of has evolved at least once (e.g. infectious cancer, tongue-replacing isopod, cartwheeling spider, parasitic males, sex-changing fish, child birth through the pelvis, ...). (we could call call these the Biological Laws of Weirdness)
Surprisingly however there is only one not entirely convincing example for male lactation in mammals. This is even stranger given that a) male care (sans lactating) does occur in mammals, b) male mammals are anatomically absolutely capable of lactating and c) it is easy to come up with scenarios where it would be quite beneficial for a male mammal to be able to feed its young.
The whole thing is puzzling enough that it even deserved a paper in TREE.

Weird people

The issue came to my attention again recently when I stumbled upon a small article in a swedish online newspaper about a guy who tried to train himself to lactate (I think people fulfill the same two rules of weirdness I mentioned above). While this shows admirable determination (and imperviousness to social pressure as we will see in a moment) this is in my opinion nothing to write home about - as I said people are weird and if the guy wants to lactate, be my guest. The real eye-opener came when I started to read the comments to the article. I do not recall the exact numbers but out of 40-50 comments more than three quarters displayed negativity ranging from ridicule over denial to outright foaming, spittle-spraying rage. This reaction absolutely astonishes me. I mean, I am certainly not eager to try it myself, but come on guys, why does it bother you so much that this one swedish boy tries to squeeze some milk from his nipples?
I do not want to overinterprete the matter but I think this might be a sympton of some deep insecurities many men have concerning their gender roles. Maybe I will write a blog post about that...

Epilogue

While looking up the references for this post I found out that I have actually been in good (if not the best) company with my puzzlement. It seems John Maynard Smith asked the same question in his 1978 book "The Evolution of Sex". Thirty years and we are still left to wonder...