Extreme polygamy may be driving southern elephant seals to early death

March 24, 2023 10:40 PM

Pressures of extreme polygamy may be driving southern elephant seals to early death. Study finds males, who can command a harem of up to 100 females, driven to gain weight as quickly as possible by foraging in areas full of predators.
posted by chariot pulled by cassowaries (8 comments total)

I attended a talk once that refered to Monogamy as a "public health technology". It was a bizzare argument involving mostly analogies to chimpanzee warfare and dolphins. The gist is that small groups of mammals (think packs, troups) as opposed to herds have disproportionately higher pecking order mortality and are in a chronic state of internal rivalry for sexual status.

I suppose we could add sealions to the anecdote.
posted by anecdotal_grand_theory at 10:26 AM on March 25, 2023 [1 favorite]

ugh, hard relate
posted by allegedly at 10:30 AM on March 25, 2023 [2 favorites]

I wonder if this is sort of an evolutionary pushback that allows more males to mate and thus avoids limiting genetic diversity on the male side.
posted by TedW at 12:31 PM on March 25, 2023 [2 favorites]

Write a chapter on THIS for your next book, Jordan Peterson.
posted by Saxon Kane at 2:07 PM on March 25, 2023 [1 favorite]

This is why you keep your harems to like six or seven, max
posted by Merus at 6:17 PM on March 25, 2023

Very interesting. But it makes sense: the unsuccessful, basically 'excess' males have nothing to lose, reproductively, by taking risks if it might put them into the winner's circle (control of a harem).

In fact I suspect that if you ran a simulation, there's probably a Pareto optimum where the males take greater and greater risks until the number of survivors of the risky behaviors aligns to the number of 'beachmasters' necessary to "defend" (that sounds a lot like "control" to me, but okay) the females.

I attended a talk once that refered to Monogamy as a "public health technology".

I have never heard it couched in those terms, but I have heard it discussed in terms of strategic advantage between competing populations (of humans, although it might apply elsewhere).

Basically, the argument is that male-dominated polygyny creates an inherent "lost boys" problem where a significant percentage of the male population isn't incentivized to work for the benefit of the community, but rather competes wastefully against each other, often doing very high-risk activities if they think they have a chance to become successful and have their own harem, or eventually becoming discouraged and embracing a low-effort permanent bachelorhood on the outskirts of the community until they die.

In contrast, a population with enforced monogamy ("thou shalt not monopolize more than one female") retains more male members in the community. They may not be strictly necessary from a reproductive standpoint, but keeping them in the community is advantageous compared to a community that basically throws them away. And since they aren't necessary for reproduction, they can go do hyper-risky activities once in a while, like engage in warfare.

From the same starting conditions, a monogamous strategy thus ends up being the advantageous one because it allows a greater number of individuals to be used for resource-competition activities at any point in time.

Obviously though, these are really oversimplified thought experiments. Extrapolating them into complex, modern societies is something only an idiot or a podcast host would do.

What has always surprised me though, is that physiologically modern (upright-walking, narrow-hipped) humans have an approximately 50/50 sex ratio at birth, despite reproduction being horrendously hazardous for females. You'd sorta think, given the hazards of pregnancy and childbirth compared to the ease of getting someone pregnant (particularly if we are considering the long prehistorical timeline when most of modern human evolution occurred), that it would make sense to start off with more females than males. And yet we don't see that, so presumably it's not advantageous enough to be selected for. Right out of the gate, human societies have a built-in excess of males vs. what is "reproductively necessary". From that alone, we can probably say with confidence that there is something more complex going on.
posted by Kadin2048 at 8:34 PM on March 25, 2023 [3 favorites]

There's a book called Animal Weapons which had a silly (publisher-driven, I assume) spin relating antlers and tusks to human tech.

What it was really about was mostly dung beetles (the author's research area), and more generally why animals would develop ridiculously oversized weapons like antlers in the first place. They tend to be pretty pointless except in the semi-ritual combat against other animals of the same species, and come at a really high, resource depleting, health-damaging cost. (A stag gets seasonal osteoporosis because of the amount of calcium antlers need.)

It's related to sexual selection, but specifically when there is a physical location that's important (like a good ball of dung, or per TFA apparently the right beach.) Getting big means you can scare off rivals and guarantee resources to your offspring, and the physical part of this makes it obvious to your prospective mate that this is true before they commit. A seal can't fake having been successful enough to get fat.

In cases where resources can't be controlled the same way, sexual selection can still involve pointless physical displays, but they tend to be things like peacock feathers rather than fights with other members of your species.
posted by mark k at 12:00 PM on March 26, 2023

ugh, hard relate

You're, allegedly, swimming in dangerous waters?
posted by BlueHorse at 1:42 PM on March 26, 2023