8 ms·
8k years ago, 17 women reproduced for every 1 man
- ProjectArcturis 3y agoCorresponds with the advent of agriculture and early civilization. No doubt rulers had more offspring than peasants, as did successful conquerors.
- AequitasOmnibus 3y agoOr put differently, 8-10 thousand years ago, the number of men reproducing dropped significantly. That makes sense to me given that this is the period in human history where society begins to form into agrarian communities [1]. The beginnings of social stratification would likely impact reproductive trends. Saying that the development of society caused more sexual competition among men isn’t crazy. This study basically uses Y-chromosomal tracing to support that point. [1]: https://en.wikipedia.org/wiki/Timeline_of_prehistory#cite_note-60 https://en.wikipedia.org/wiki/Timeline_of_prehistory#cite_no...
- francisofascii 3y agoSo would you say this is a recent trend of the last 10K years? And perhaps it was more equal going back a million years ago?
- _ache_ 3y agoMillions ? Lucy isn't an human and yet 3M years old. Humankind is about 300K year for Homo sapiens and half of that about what can be called modern human.
- sdwr 3y agoIf I understand correctly, the crux is this graph? https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Click%20on%20image%20to%20zoom&p=PMC3&id=4381518_459f02.jpg https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/t... Showing total # of male ancestors (left) and female (right) I guess writing, agriculture, and fixed settlements allowed for dominance on a far greater scale. There's a natural limit to how much power you can project without technology.
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- freitzkriesler2 3y ago8-10k years ago puts us at the near end of the last ice age. I know it's poo poo'd in academic circles but if there was a great flood that destroyed most of human civilization that would also describe why this occurred.
- nh23423fefe 3y agoI dont see the connection
- mcphage 3y ago> if there was a great flood that destroyed most of human civilization that would also describe why this occurred Do floods kill significantly more men than women? How much area would need to be flooded to affect most of human civilization 8-10k years ago? By that point we were spread out throughout the entire planet (except what, Polynesia and New Zealand?)
- locopati 3y agoTo the extent there's evidence of a great flood, it hardly destroyed most of human civilization.
- dirtyid 3y agoIs the suggestion elites were controlling access to procreation? Maybe men were also just killing each other extra fierce in the land grab. Uncompletely uneducated speculating on my part.
- mdhen 3y agoDefinitely a factor. As agrarian societies expanded into hunter gatherer territory they would kill the men and take the women. Agriculture did not spread because it was a better deal for the individual at the time, it spread because it could support higher population density and specialization, including a warrior caste. And thus was more succesful at conquering and holding land.
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- daniel-s 3y agoIf that were the case why did humans not evolve to have 17 times more female babies than male? The chance of a billionaire having a son is 65%. https://www.bbc.com/future/article/20161014-why-billionaires-have-more-sons https://www.bbc.com/future/article/20161014-why-billionaires...
- eafer 3y ago> If that were the case why did humans not evolve to have 17 times more female babies than male? https://en.wikipedia.org/wiki/Fisher%27s_principle https://en.wikipedia.org/wiki/Fisher%27s_principle
- HPsquared 3y agoWorker bees. Not everyone needs to reproduce for the group to prosper.
- mo_42 3y agoI think we cannot compare humans with worker bees as these bees cannot reproduce. Basically, only the beehive is an complete organism. For the latter part, I'd argue along the lines of the selfish genes (Dawkins): Not an organism wants to reproduce but rather the individual genes. They use the body as a vehicle for that. So it can still make sense for an individual to not reproduce and increase the chances of the same genes to be passed on (e.g., when an uncle without kids supports the kids of his siblings).
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- Veuxdo 3y agoWhile a son would have a much lower chance of reproducing, if he does, he'll reproduce a lot. I think that's the balance.
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- b800h 3y agoWhat's the number now? I'm assuming that the falling popularity of monogamy means it's headed in the same direction again, albeit not in quite as extreme a way.
- biomcgary 3y agoThe falling popularity of reproduction probably intersects with the falling popularity of monogamy, albeit in unclear ways. All these trends are linked to reliable contraception, which disconnects sex from reproduction; however, I suspect that contraception merely facilitates / accelerates the cultural trends rather than being their primary cause.
- micromacrofoot 3y ago> probably intersects with the falling popularity of monogamy this sounds like a bias looking for data to suit it birth rates generally decline as countries become more developed, there are numerous suspected causes (not related to monogamy)... generally the rule of thumb is... as education and income go up, birth rates decline: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255510/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255510/
- biomcgary 3y agoMy use of intersect was not fully articulated, thus unclear. My focus is genetic, not sociological. That is, I'm not saying that the rate of monogamy and rate of reproduction are causing each other. Rather, the intersection that I have in mind is whether the two things would have synergistic impact on allele frequencies (i.e., demographic structure). In the extreme, if a population stops reproducing, sexual selection doesn't occur (genetically) even if all sort of interesting sociological phenomena occur.
- sublinear 3y agoA name isn't quite what it used to be. Monogamy and large families no longer have the social power they once did. It's all been replaced by money and new forms of communication. People may call this unnatural, but I wonder if other animals have similar behaviors that limit reproduction.
- SillyUsername 3y agoI don't know of any biologically born men that can reproduce...
- didip 3y agoWill humanity go extinct if our birth rate continues to plummet?
- oivey 3y agoNo, even with lower birth rates there are going to continue to be many, many humans on earth.
- kspacewalk2 3y agoIf fertility rates remain below replacement levels, then eventually we will go extinct. How far below replacement determines how quickly this will happen.
- beebeepka 3y agoHuman population is still growing faster than we can manage long term, so it's way too early to worry
- francisofascii 3y agoThe low fertility rate is not very uniform across cultures. Some pockets of society have high fertility rates which would keep things going. Also, fertility rate cultural norms can easily reverse a few generations down the line.
- kspacewalk2 3y agoI'm speaking of the overall, global fertility rate, which is currently around 2.3.
- raspyberr 3y agoIf there are fewer people, there's less competition and more resources, people get more stuff, people get happier, and have more children.
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- SoftTalker 3y agoEditorialized title; the actual title is "A recent bottleneck of Y chromosome diversity coincides with a global change in culture" Seems to boil down to "the high status, high power males got all the women" which is unsurprising.
- Palmik 3y agoIt's one of the key results from the paper. From the abstract: "In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky." From the body: "However, the Y chromosome plot suggested a reduction at around 8–4 kya (Supplemental Fig. S4B; Supplemental Table S4) when the female Ne is up to 17-fold higher than the male Ne (Supplemental Fig. S5)." Indeed, the title does not match the title of the paper, but hopefully makes it more approachable.
- hulitu 3y ago> 8k year ago, 17 women reproduced for every 1 man A long, long time ago, in an universe so far away... Those people don't know what happened yesterday, but they know for sure what happened 8k years ago.
- matt3210 3y agoToday there is a correlation between women’s rights and reproductive rate. I wonder if that correlation existed during the era represented in the study. If so, it must have been particularly brutal.
- a0-prw 3y agoI had never heard of "cumulative Bayesian skyline plots". A search on Google gave one hit, which was a dissertation quoting this study. I assume they mean "coalescent Bayesian skyline plots". Why invent a new name for something which already has a more informative name? I have great difficulty imagining a culture which could socially sustain an N_e of 1:17 (male to female). Just do a few sample calculations. The priviledged males would be massacred. A few things could explain it: (1) large scale male infanticide or male child castration (2) A disease which kills mainly male children. Both of these alternatives suffer from one of the same problems as their proposal: How would the cause (whatever it was) spread so relatively quickly among distantly seperated populations ? I think it far more likely they have made mistakes somewhere.
- Reubend 3y agoI agree. 10,000 years ago it would have been difficult for majors trends to spread across different continents. And I have a guess (though unsupported) that every civilization's mythology would tell similar stories of this event if it really were occurring globally.