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Bob Henke Commentary: The (sometimes) deadly mating process

Bob Henke Commentary: The (sometimes) deadly mating process


So there I was, having breakfast in my favorite restaurant, when I suddenly felt a woman’s fingers closing around my throat.

This sort of act is not highly unusual; it is, in fact, quite common around home and certainly not unknown in at least one of my workplaces. During one memorable hour, this group of ladies was responsible for me being struck, throttled, bludgeoned, threatened with death and stabbed with a pen — and that hour was during our mandated workplace violence training last year. I think they misinterpreted the purpose of the training.

No, the unexpected part of the most recent incident was the location. Her explanation was basically, what did I think would happen if she saw me sitting with my back to the door when she came in?

This nonchalance was shared by most of the other women witnessing it but Dr. Wifey went even further. She chewed me out.

“Do you know what you said when Karen started choking you?” I did not but apparently it was, “It wasn’t me. I didn’t do it.” My transgression was, since at first contact, I had no idea who it was, I therefore could not know if it was deserved or not. And that, by the way, is the problem with men. A male will always claim he is not guilty whether he was or was not, so how could any woman believe him? It was sort of iffy whether I got it again just for not being guilty of anything the first time.

It is all very confusing and I presume no one with a Y-chromosome could ever understand.

I am quite often chastised for suggesting there is a difference between males and females, whether human or otherwise. However, given the general way reproduction is handled throughout the animal kingdom and parts of the plant kingdom, this difference not only exists but is necessary if a species is to be successful. It is a simple matter of form following function. I had occasion to ponder this recently thanks to a question from a reader who wrote:

Why do male mice die after mating?

This sort of threw me. Dying after completing the mating act is called semelparity. Suicidal reproduction of this sort is common in nature. All annual plants practice this. So do Pacific salmon, a few amphibians and reptiles, and — most famously — insects. Everyone has heard the tales of praying mantis females biting the head off the male in mid-mating, letting his twitching body complete the transfer, then consuming it.

Male spiders have two sperm-transfer organs, called pedipalps, which they insert one after the other in the females’ two storage areas. With of some of the common orb weavers in this area, immediately after the second one is inserted, the male suddenly ceases all respiration and dies. His lifeless body hangs from her, making it impossible for other males to mate with her. After a while, she gets tired of dragging his corpse around and eats it but by then the fertilization is complete so any new males that get fresh also get taken to dinner — not in a good way.

Although semelparity has not traditionally been associated with mammals, one could also make the case that for the majority of males, at least trying to mate is fatal. Although born at roughly equal rates, the genders have markedly different survival rates. From an evolutionary perspective, females must survive. Males need only live long enough and in sufficient numbers to make sure the females are inseminated.

In the majority of species, the female chooses — the male displays. The level of competition quite often either causes a great deal of mortality among the males or significantly drains energy to the point they cannot survive beyond the mating season. Post-mating mortality is seen in everything from deer to sunfish to songbirds and it is predominately a male issue.

In many instances, males tend to be the method for knocking themselves off. Bright-colored rooster pheasants parading up and down open areas are prime targets for predators (and motor vehicles if they choose to strut the open road shoulders). Male cervids (deer species) spend so much energy rushing to new territories looking for does, fighting with each other, tending lines of scrapes, using huge amounts of energy to grow huge bony antlers, and ignoring food and drink during the rut that they often so weaken themselves sufficiently to succumb to either disease or weather before the following summer.

Nature even discriminates against maleness in the womb. In many instances, under conditions of stress, females will abort fetuses. The evolutionary reason for this is the huge amount of effort needed to successfully raise an offspring. It is best not wasted on a baby that may not survive the current circumstance. Better to wait until things improve and produce another offspring when it is more likely to thrive.

Primates (including humans) are some of the better studied species but we know many mammals from deer to muskrats will spontaneously abort in bad times. The mechanism is that stress causes the liver to release hormones called cortisols. This is very damaging to some of the fetuses and if the stress lasts long enough, it will be unable to survive. The interesting thing? It is only damaging to males. Female fetuses at any stage tend to be immune to cortisol. There are always extra males but females must be preserved so, even in dicey times, a female offspring is always worth a try.

This is all interesting, but still does not deal with the sexual suicide of mice. Turns out, after a few hours of research, it actually does exist, but the victims are not mice. It occurs in a group of species (there are four) that are small, insect-eating marsupials found in Australia and some outlying islands. Known as antechinus, they have a critical need for young to be weaned just as the short peak of insect production hits in order for them to learn to hunt on their own.

Females are all receptive at the same time and must all breed within a very brief period. Males spend the first months of their life eating furiously and growing enormous testicles. Just before the mating season, massive amounts of sperm are produced and stored, whereupon, somewhat alarmingly, the males’ impressive testes wither and drop off within a period of days.

The race to breed is then on for precious sperm is being spilled each time the animal urinates. When a female is found, a mating frenzy ensues that may take as long as 14 hours before the tiny male has ejected all his semen. The activity is so intense and takes so much energy that the male is but a husk at the end, hemorrhaging internally, and most die within a few hours.

I think it is definitely semelparity but some biologists have suggested it is nothing more than a more precipitous version of differential male survival. Whatever the ultimate finding, I think the inescapable conclusion is that there definitely is a “battle of the sexes” and males have already lost.

Bob Henke writes a weekly outdoors column for The Post-Star.


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