Humans and eusociality

[Ericchiriboga]

E. O. Wilson (and others in the minority) consider humans to be eusocial, arguing that menopause constitutes a sterile caste, similar to worker ants. He also made the argument that it's (respectfully) possible that homosexuality is a eusocial caste or culture-imposed monastic orders are. 

My thoughts are as follows:

I feel the homosexuality argument is a little flimsy, as it's been documented in non-eusocial animals (and seemingly appears too infrequently to be "caste"), and invoking something like a religious order as evidence of eusociality seems odd to me as it implies that some cultures are more eusocial than others. The postmenopausal argument is a little thought-provoking, but it's a little hard for me to conclude humans are eusocial solely on the basis of that.

Does it mean that each family is then one little eusocial unit, comparable to a whole colony of ants? It's just so radically different from eusociality in every other form I know, genetically and behaviorally (I will admit I'm more familiar with it in ants and bees and not so familiar with it in shrimp and beetles). There are also a few other mammals like killer whales that undergo menopause as well; are they eusocial, too?

I don't know, my natural inclination is to not really buy into this, but I'm open to having a discussion on the topic. 

[CharonY]

To give a more general take: I always found the concept of sociobiology fascinating, but similar to social sciences (as opposed to biological sciences) the ability to make testable predictions is fairly limited. The controversy and discussion around Wilson and others are less about the whole theoretical framework (I think) as it is well thought-out and in many cases quite a compelling narrative.

Where I struggle is ultimately how and whether individual evidence actually fits the biology. It has been quite a while (in fact decades- I was reading most of it during my student days) but I recall vaguely that the argument for existence of sterile castes was fundamentally a kin-selection argument. I.e. that the sterile individuals help their genes survive by supporting relatives (and basically that was extended to the argument of altruistic behaviour- one of the topics I was really interested in).

However, over time data showed that insects do show altruistic behaviour without being related (e.g. not all bees in a hive are necessarily related, I believe, memory is a bit fuzzy) and also other cases where high degrees of relationship were not predictive or associated with altruistic behaviour. I think eventually Wilson gave up on that idea (maybe around 2010ish?), which caused a bit of an uproar and I recommend seeking that paper out.

The result was a much tighter, narrower framework that shed the inclusive fitness aspects and was closer in line to what we actually observe in social insects. I have not read his later books where he might have speculated about human societies, but it is again important to highlight that the data is almost entirely based on insect studies. As such, they remain extrapolations and speculations and it is not clear whether they have actual scientific value at this juncture. 

[Ericchiriboga]

I actually learned about eusociality through a kin selection lens, too, with even naked mole rats being an example because how inbred they are, and I just graduated. 

I'm guessing the paper you're talking about is The Evolution of Eusociality in Nature in 2010? Is that sort of the start of the move towards multi-level selection models?

[Sensei]

8 hours ago, Ericchiriboga said:

arguing that menopause constitutes a sterile caste, similar to worker ants.

Nonsense.

Search net for keywords:

"female eggs quality per age graph"

"female eggs count per age graph"

"female eggs at birth"

e.g. "By puberty, she usually has half that—and each month after puberty, she loses up to 1,000 eggs. Of those, only one egg is matured and ovulated each month."

Similar like with male sperm, only a fraction of them are good quality and should be used for reproduction. That is why medics working on in-vitro have so large failed pregnancy rate. It takes a long time to find out which egg and which spermatozoid are in good conditions and are able to survive and form an embryo.

From around 1,000,000 eggs at female birth, typical women has 1 to 3 child. One per a million, one per a half million, one per 333 thousands, chance of becoming human. The rest dies. Live people are "lucky" ones..

8 hours ago, Ericchiriboga said:

menopause

..majority of ever living women in the history of this world, never reached to menopause, because they died a long before 40.. Long life of modern human is result of modern medicine, mass vaccination, decreased chance of dying during pregnancy and childbirth, cleaner environment and rules of making and preserving foods etc. standards..

e.g. search net for maternal mortality rate.

https://ourworldindata.org/maternal-mortality

One hundred and more years ago, it looked much worser than on the graph in the article.

[Ericchiriboga]

That's a fairly compelling argument in theory, that most women haven't historically reached menopause, but I don't know if it's true. The data you linked certainly point to high maternal mortality rates, but it's about 5% (assuming 5 children) in Finland in 1800. There are definitely more morbidities at play than just death from childbirth and we're only looking at a sample size of one country (and maybe the data is still too recent), but that's just not a firm conclusion I can draw.