strange behaviors

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    The Species Seekers:  Heroes, Fools, and the Mad Pursuit of Life on Earth by Richard Conniff is “a swashbuckling romp” that “brilliantly evokes that just-before Darwin era” (BBC Focus) and “an enduring story bursting at the seams with intriguing, fantastical and disturbing anecdotes” (New Scientist). “This beautifully written book has the verve of an adventure story” (Wall St. Journal)

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This Year’s Worst-Timed Science Study Examines Sex with Immature Females

Posted by Richard Conniff on December 16, 2017

If only scientists had better control over publication dates, this new study might not have seen the light just now, in the year of Harvey Weinstein, Dustin Hoffman, and oh-so-many others.  Published this week in the journal Scientific Reports, it’s a finding that males seeking sex with immature females aren’t necessarily engaged in coercion and don’t seem to impose any cost on their partners.

OK, the researchers are talking about redback spiders, not humans.

And lest readers think it’s a good idea to follow examples from the natural world, the press release for the study also notes that these are “one of few arachnids that engage in sexual cannibalism while mating. In fact, males have been observed to actively assist in being cannibalized by doing somersaults to place their abdomen over the adult female’s mouth.”

Still, we’re not all that far out of Harvey Weinstein territory, are we?  (He’d have used a body double for the somersault.)

What’s especially interesting, according to the press release from the University of Toronto, is that “some male redback spiders will avoid being cannibalized by mating with immature females that are not experienced in eating their partners.”

Researchers Luciana Baruffaldi and Maydianne C.B. Andrade wondered if it was coercive sex and how it affected the immature females.

“Here we show,” they report, “that a damaging mating tactic, apparently adaptive for males, is not coercive for females. Adult male Latrodectus spiders mate with immature females after tearing the exoskeleton covering the female’s recently-developed reproductive tract, which can cause haemolymph bleeding.” The males also skip some of the courtship behaviors they would display to mature females, and the immature females engage in “elevated deterrent behavioural responses.”

These deterrent behaviors take energy and increase the female’s risk of predation or other damage, but they “may evolve if they allow avoidance of costly matings with coercive males.” So far, so good.

Then the co-authors add the genuinely disturbing–even creepy–thought that “these behaviours may also be a mechanism of female choice if persistent or physically powerful males are superior mates.” It’s disturbing, it seems to me, because it inadvertently echoes the common notion among human males that a female saying “no” is actually a female engaging in combatively flirtatious resistance, en route to “yes.” One can especially imagine the Donald Trumps and Harvey Weinsteins of the world disbelieving “no” based on the assumption that they are clearly superior males.

Still in the creepy vein, the co-authors go on to argue that “it is not possible to distinguish the function of female deterrent behaviours only by observation. By extension, it [is] not possible to determine whether matings are coercive based on female responses. The critical question is whether or not females suffer net fitness deficits when they mate with males that use coercive tactics.”

In this case, says Baruffaldi, “this early mating may be good for female redback spiders because in nature they’re at risk of not finding a mate at all.”

“Not finding a mate at all” might sound pretty good, in the circumstances. But the press release also notes that “unmated females have shorter lifespans than mated females, likely the result of having eggs that have to be maintained that can be a drain on their resources.”

The whole thing has a familiar ring to it: “Have sex with me, I’m your only chance.” It’s also a reminder of just how cruel the natural world can be. Cruel to the males, too, I suppose, who otherwise risk being cannibalized during sex.

The unfortunately timed University of Toronto study is part of a growing body of research on coercive sex in the animal world. But here is a hint of hope to grasp onto as we race to the end of a horrible year:  The co-authors suggest that scientists may have overestimated the prevalence of sexual conflict in the natural world, because over-reliance on studies of insects skewed their thinking. (The Natural History of Rape was the title of one controversial book on the topic, published in 2000.) As researchers have begun to look at a more diverse study species, they are finding less evidence of sexual interactions resulting in harm to females.

Coming up with a bottom line on a behavior that runs from fruitflies to the President of the United States may seem unlikely. But here’s my candidate: The phrase “casual sex” could just be the dumbest oxymoron ever invented, for redback spiders and human beings alike.




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