"Ancestral men probably competed for mates mainly by excluding competitors by force or threat"

An abstract of a paper by David Puts on Human Sexual Selection:

Highlights
• Sexual selection has been stronger in humans than is often assumed.
• Ancestral men competed primarily through force and threat of force.
• Ancestral women competed mainly through mate attraction.
• Understanding sexual selection clarifies some human psychological sex differences.

Abstract

Sexual selection favors traits that aid in competition over mates. Widespread monogamous mating, biparental care, moderate body size sexual dimorphism, and low canine tooth dimorphism suggest modest sexual selection operating over human evolution, but other evidence indicates that sexual selection has actually been comparatively strong. Ancestral men probably competed for mates mainly by excluding competitors by force or threat, and women likely competed primarily by attracting mates. These and other forms of sexual selection shaped human anatomy and psychology, including some psychological sex differences.

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8 comments:

Colin Welling said...

then why is there sperm competition? Sperm competition necessarily implies less human to human competition.

I aslo dont understand how women it can be said that women compete mainly by attraction when it obvious that women slut shame each other like crazy which is social sabotage.

n/a said...

Much of the claimed evidence for sperm competition in humans never held up.

Colin Welling said...

Here is a review of the literature article on sperm competition.

"Sperm Competition and the Evolution of Human Sexuality (2015)"

If you can't download access it I can send it to you.

They present a lot of evidence that corroborates sperm competition in humans. I don't know how often each piece of evidence has been reproduced. The most relevant piece of evidence is that women with less attractive partners are more likely to cheat.

I just down buy the idea that men primarily used violence to compete with other men. We know that men lived for generations upon generations rarely ever mixing with neighboring groups who had a different autosomal structure. Thats why farmers stayed distinct from european hunter gathers for so long even when they were right next to each other. The same is probably true with the EHG/ANE mixed steppe europeans who made an autosomal contribution to northwest europe that was just as big as the autosomal contribution to central europe. Basically, many of these different groups kept to themselves for the most part. It certainly could not have been typical for farmers to raid hunter gatherer villages and take wives because that would make the two populations autosomally the same after a short period of time. (i read your most recent post and I know that there are exceptions).

I also suspect that if violence was a big factor in male competition then there would be much less sexual competition amongst women than there was in reality. It seems that boobs and some other features of women are the result of high sexual selection which would more sense if women weren't all taken in by some strong/high status guy. Why would guy who eliminated his competition via violence (a big risk in itself) be so selective with women, i.e. choose women with big boobs?

Colin Welling said...

Anyways, its been a while since I talked to you n/a.

What do you think of all the incoming yamnaya results? Is it validating what you already suspected? Any new thoughts? Im a bit surprised that lactose tolerance may not have been very prominent in the yamnaya (however we have yet to test the western yamnaya).

Where do you think r1a (of course i mean the IE kind) came from? Ive long thought that the yamnaya would come out r1b dominant and largely lack r1a. we should soon find out if this is true in the western yamnaya.

Btw, I remember first becoming interested in the kurgan hypothesis when you were convinced that much of european genetics came from the steppe before we knew anything about ANE. It was crazy how convinced you were of the kurgan hypothesis, pointing to things like r1b diversity in eastern europe and the recent selection against mtdna C on the steppe. Turns out you were right :)

n/a said...

Colin,

You can send it to me, but I don't think it's going to change my mind. I think I'm familiar with all the basic arguments.

"The most relevant piece of evidence is that women with less attractive partners are more likely to cheat."

Yet rates of extra-pair paternity are low in humans. Low enough that adaptations for sperm competition are likely to be unimportant compared to adaptations for mate guarding and intra-sexual competition.


"Thats why farmers stayed distinct from european hunter gathers for so long even when they were right next to each other."

Part of this is probably that farming was able to support much higher population densities. So even where mixing with hunter-gatherers occurred, the resulting degree of hunter-gatherer admixture in farmers would have tended to be relatively minor.


"if women weren't all taken in by some strong/high status guy."

No one is arguing all women would be monopolized by one man. That probably would not make for a very effective group and probably wouldn't be an advisable strategy even within an isolated group (given that lower status males would have very strong incentives to ally against the monopolist). But in general higher status males would get more and/or more attractive females. And violence or threat of violence would have played a significant role in determining status hierarchies.


"What do you think of all the incoming yamnaya results? Is it validating what you already suspected? Any new thoughts? Im a bit surprised that lactose tolerance may not have been very prominent in the yamnaya (however we have yet to test the western yamnaya)."

I expected the Yamnaya to be more depigmented than they now appear to have been (given the levels of depigmentation seen not too much later both in Europe and in Indo-Europeans of the eastern steppe). Other than that (and possibly the LCT results), the results are more or less as I expected.


"Where do you think r1a (of course i mean the IE kind) came from? Ive long thought that the yamnaya would come out r1b dominant and largely lack r1a. we should soon find out if this is true in the western yamnaya."

I believe R1a and R1b ultimately came from the steppe. But it looks like around the time of Yamnaya, the people carrying R1a ancestral to most later Indo-European R1a were to the north and/or west of the Yamnaya. The second of the recent Yamnaya ancient DNA papers suggested the migration went Yamnaya west to CW (where they probably picked up R1a and additional depigmentation alleles) and then Corded Ware back east to form Sintashta/Andronovo.

Colin Welling said...

Ok, ill send you the paper. It is more like a summary highlighting previous studies.

"Yet rates of extra-pair paternity are low in humans. Low enough that adaptations for sperm competition are likely to be unimportant compared to adaptations for mate guarding and intra-sexual competition."

Well, perhaps these kids are out of wedlock so cocoldry is not necessarily implied.

The point is that women are more likely to seek out more attractive men if they are with an unattractive man. I assume that in addition to mate, which partially combats cheating women, another strategy is to simply seek out your "equal" so that there is less reason for the woman to cheat. That is, assertive mating based on attraction.

"Part of this is probably that farming was able to support much higher population densities. So even where mixing with hunter-gatherers occurred, the resulting degree of hunter-gatherer admixture in farmers would have tended to be relatively minor."

Thats not the impression i get from the ancient dna. Haak basically showed us that the farmers moved into europe as a highly homogenous populations and it wasn't until the middle neolithic did we start to see significant increases in WHG. As for how EEF even developed in the first place is still a mystery. Davidski actually suspects that EEF was already forged in turkey which means that little admixture occurred all the way throughout the early european neolithic.

On the flip side one can talk about the hunter gathers surviving for a long time in sweden right next to farmers which would have required continuous presence of hg women that were not taken by the much more populous farmers. We also have evidence of hg men being taken into farming cultures which only adds to the necessity of hg not being taken by farmers.

I have a strong feeling we will see a great deal of similarly sized populations, that are autosomaly different, living side by side but not mixing.

If true, it would be a very interesting twist in human evolution. We could then argue that racism is mechanism for peace for if men were racist (not quite the right term) enough, they would not have felt the need to compete with men of other races to take their wives.

Of course this alone would not disprove the idea that men used violence to compete with other men within their race, for the same race women, but it would disprove that men used a lot of violence for other raced women.

Colin Welling said...

"I believe R1a and R1b ultimately came from the steppe."

Why do you think r1a came from the steppe? Would if it just went from north eurasia to northern europe along the forest zone?

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