Die Fledermaus

It was only the second warm evening of the year and a Friday no less, so I came home at 5. Iris, having also noticed the weather, was up at Warnemunde, strolling the beach line of the still frigid Baltic with a couple friends, so I decided to go for a walk myself. The riverfront in town, which as been transformed from port to shops and restaurants, had been surrendered all winter to the ice and wind. The brick walkways and cement steps along the riverfront were still strewn with New Year's Eve firecrackers and beer bottles. The ice that had covered the Unterwarnow was gone, and the only remaining snow was nubbins of the huge piles the city had dumped in a parking lot. I strolled along the waterfront, enjoying the presence of other people in a place that for six months had been abandoned, and watching the grebes bring up small wriggling bits of silver from the river. The Institute is on the waterfront and I came to it as the sun went down. I thought about going inside to see if any colleagues wanted to stroll with me, but decided instead to wander through the unoccupied lot next door. That whole section had been a major port and while much of it has been built over, much, including the peace next to the Institute has gone to grass and the occasional tree. A two-story heap of dirt and rocks, dug up to make space for some building's foundation, is all that distinguishes the lot from a small unmaintained park. As I gazed up at this heap in the fading light, something fluttered over and around it. The silhouette of a tiny bat flitted and floated, gliding and diving after nothing I could see. I tried and failed to detect any insects it could be after. yet it repeatedly visited the same spots, just under those exposed tree roots, just over the top of the dirt pile, just past that lighted window of the Institute. closing my eyes and concentrating, I could just barely hear its wings and a rapid ticking at the upper end of audibility, the lowest notes in its echolocation. I could hear no insects flying, calling or crawling. Watching the lightest part of the sky, I spotted a single midge flying a few feet from my head. Moments later it had disappeared into the hunting bat. This qualified me to be added to its circuit; on each subsequent round of the lot, it would make a small circle around me, perhaps a meter way, checking what other insects I may have attracted. I watched it past when I could see anything, and will return on subsequent dusks.

Adaptive male lactation?

It has long been known that male mammals, including male humans, are physiologically capable of lactating. Screw with a man's physiology by giving him the right hormones, or the wrong series of starvation and then plenty, and he may start to produce milk. No one, as far as I know, has ever suggested that this is adaptive, that this capacity exists because men gain some reproductive advantage through lactation. Rather, it is usually seen as a result of the fact that we share almost all of our genetic material with females, who do make good use of their lactational prowess. Male lactation across the mammalian world is largely thought to be a side effect of intersexual correlation, the tendency for the two sexes of a species to have similar traits.

I am therefore skeptically excited to read that males of two species of fruit bats, one in Malaysia, and one in Papua New Guinea, are said to have "well-developed lacteriforus ducts and underlying mammary tissue similar to that found in lactating females" and that milk has been "expressed" from a large number of male bats.

It is not actually known whether these males are feeding young, and if so how commonly and to what effect, but this is the closest suggestion I have yet seen of the possibility of adaptive male lactation.