The evolution of expendability: Why some ants traded armor for numbers

Ants with lots of workers tend to put less energy into making them armored.

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[Uncivil Servant]

I wonder what the dividing line is between kin selection and eusociality - or is there even a clear boundary? For example, if we pick on hominids, there's the hypothesis that homosexuality/asexuality/childfree behavior massively reduces the reproductive fitness of the individual, they still have utility for the tribe by providing members that aren't directly occupied by childrearing roles (plus bisexuality can be used to help cement social bonds if you're a bonobo).

The obvious line that people point at would be differences in body morphology, but the eusocial shrimp that you link don't have huge differences between fertile and infertile females - only the fact that the former can be seen carrying eggs around.

No, it would require significant changes to human reproduction. Reproductive medicine is already a politically charged topic, I just can't see it happening*.

There are practical implications as well: I'm not sure that you can get there from an XY sex system. XX individuals who self-fertilize can only have daughters, but eusociality generally requires haploid males. Leaving aside the question of whether haploid vertebrates are even viable, you'd at least have to start with a sex system with WZ females and WW males. These animals exist, and some snakes have been documented to give birth without ever mating, but only to diploid WZ and WW snakes.

And that haplo-diplo lifestyle is also a major change, plants go through this which is why they produce pollen, tiny spores capable of hatching and growing short-lived male gametophytes, like if one's testes produced little mini-testes instead of sperm. So yeah, once you start borrowing plant-style haplo-diplo life cycles, you're pretty far removed from mammalian biology.


*It has been tried in the past with castrated slaves, but that's a bit drastic and also not an evolutionary procedure

 

[Uncivil Servant]

I thought of a different and more recent parallel - the move from hunting-gathering to farming, on the order of ten thousand years ago. I don't know if it is a hundred percent authenticated, but it seems to be often said that nutrition quality and health took a step down, in the interest of larger populations and civilisational development.

Nutrition actually likely improved, but infectious disease became a major problem. One thing to remember when comparing early civilizations to contemporary hunter-gatherers is survivorship bias. Cities could afford to keep marginally-productive individuals alive in ways that nomadic hunter-gatherers or even sedentary subsistence farmers simply cannot, regardless of morality, even as those same cities bred deadly diseases.

But yes, civilization brought with it specialization of tasks and societal strata and a number of social roles that converge on eusocial animals. This came about from the abundance of resources allowing individuals to focus on more than their own immediate survival.

If early cities began already possessing antibiotics, vaccines, clean drinking water, and contraception immediately, leading to a surplus population and the ability to control it from the get-go, perhaps we could have gone in that direct...oh wait, never mind, China tried that with One Child. As usual, that country is an invaluable source of "don't be That Guy" throughout history. Yeah, even if given the tools, humans would mismanage the transition, fail, and "natural" humans would continue to flourish.