What would Sigmund Freud and Charles Darwin say about the erotic lives of male spiders?

In his 1920 essay Beyond the Pleasure Principle, Sigmund Freud identified Eros (the Greek word for erotic love) as a primary impulse driving humans toward sexual pleasure and the creation of new life. The father of psychoanalysis also gave Thanatos (Greek for death) an important role, suggesting that a desire for obliteration, too, is part and parcel of sex.

Since 1895 when Freud began publishing, his adherents and critics have argued ad nauseum about the degree to which he understood men and women. The merits of the arguments don’t matter here. What does is the idea that … hmm. Maybe Freud would have had better luck writing not about human sexuality but spider sexuality. If he had, surely his concept of Thanatos would have caught less flack.

This is because, for males of some spider species, sex almost always involves dying. Even so, they don’t hesitate to engage in it.

Indeed, according to scientists collaborating from universities in the Czech Republic, Germany, and Israel and publishing in the journal Animal Behavior, dying during sex may be an important aspect of what male brown widow spiders (Latrodectus geometricus) are seeking.

The Study

Brown widows are slightly smaller cousins of black widow spiders, and are usually found in tropical and subtropical areas. (The species is called “widow” because, by killing the spider that just inseminated her, the female becomes temporarily mate-less. The “geometricus” part of the Latin name refers to a geometric pattern on a brown widow spider’s back.) As they mature, female brown widows change shape and size, eventually becoming about three times bigger than the males.

The researchers began their study by isolating females in individual boxes. At a male:female ratio of 1:1, they then allowed virgin males into the boxes of single females. They noted that males never mated with young females. Ninety-five percent of males given the opportunity mated with adult females and ninety-one percent of males given the opportunity mated with “late-subadult females.” That’s the category name for females who are almost ready to moult into their adult size and shape.

Males copulated with adult females a total of one hundred eleven times. Eighty-eight percent of those males were cannibalized during the sexual act. Males were never cannibalized by late-subadult females,  though one female did cannibalize a potential mate before copulation had begun.

Because late-subadult females can be fertile, the researchers expected that, if given a choice between late-subadult females and fully adult females, males would prefer to mate with the late-subadults who were probably not going to eat them. To the researchers’ surprise, that was not the case. When the team presented males with late-subadult and adult females simultaneously, the males chose the carnivorous adult females seventy-one percent of the time.

Score One for Thanatos?

Actually, not. The theories of Charles Darwin probably do a better job of explaining why male brown widows are drawn toward sex with the females who will devour them.

Writing more than seventy years before Freud, Darwin’s first landmark book was On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life. It proposed that the ancestors of each and every one of the many complex forms of life on earth were a few sexless, featureless, single-celled organisms. It took about 4.5 billion years for those few simple bacteria to evolve into the trees, whales, cephalopods, poison ivy, bear cubs, reagweed, roaches, Venus flytraps, leaf-horned frogs, algae, and kittens that surround us today.

In animals, evolution happens mostly sexually. As Darwin explained things, mating in animals is not only a procreative act, it’s a narcissistic one. Whether or not an animal is consciously aware of its motivation, when having sex every single one is acting upon an innate drive that might guarantee its DNA a significant and stable place in the world of tomorrow.

Why Male Brown Widows Gravitate Toward Sex that Will Kill Them

Brown widow spiders have lengthy courtship routines that involve the female’s web. Males cut and bundle parts of the web, and they add to the web from their own supply of silk. The male also vibrates the female’s web.

The research team did not conclusively identify an evolutionary explanation for why male spiders in their lab courted and mated more often with fully adult females. Possibilities they raised included:

·     Adult females may produce either more pheromones or more attractive pheromones. Male brown widows are often found on the webs of late-subadult females. However, that’s usually where matters began slowing to a stop. “When paired with late-subadult females, the courtship is considerably shorter than with adult females,” Lenka Sentenská, a University of Greifsvald zoologist and a co-author of the paper, explained by email. “Males rarely alter a female’s web and engage mainly in vibratory behaviour.”

·     Because their sperm storage receptacles may not be fully developed, late-subadult females may not represent truly safe harbor for fertilized eggs. Late-subadults still need to go through the physical challenges of their final moult. Either they or their eggs might not survive.

·     Being killed and eaten may actually increase a male’s odds of fertilizing eggs. The male’s body serves as nutrition for the female and her eggs — so much so that, post-coitus, the female is less likely to immediately mate with a competing male.

·     When males mate with adult females, they do a somersault, the end stance of which positions them perfectly to deposit their sperm into the female’s receptacle. For whatever reason, when mating with a late-subadult female, males don’t somersault. The lack of the flip may create enough mechanical imprecision to make the male deposit his sperm slightly off-target.

Darwin might have speculated that, for whatever reason, when a male brown widow offers himself up for obliteration he is acting upon a hard-wired, evolutionary imperative that can help him guarantee his genetic material a place in generations to come. Dying is part of what the male seeks during sex —whether or not he is aware of that.

Come to think of it, Freud’s idea about Thanatos includes the fact that any sexual “death instinct” is largely subconscious. And, of course, Freud wrote about humans, while Darwin wrote about all living beings regardless of their consciousness. Indeed, Darwin wrote about life itself.

Still, in some small ways, it’s kind of fun to imagine that, in theorizing at least, Freud and Darwin occasionally directed their very different hammers at precisely the same head.