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Analysis of DNA uncovers a rough dating scene after the advent of agriculture

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Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#21

Post by swagasaurus-rex »

sloreti wrote: post #18

"In more recent history, as a global average, about four or five women reproduced for every one man" Correct me if I'm wrong, but isn't this the same as saying one man, on average, will father a child with about four or five different women? I suppose given the timescale being discussed, "recent history" may mean the last few centuries, but this average still sounds very high to me.

Yeah, it isn't clear what timescale they are discussing, but the graphic suggests that a near 1/1 pairing is a very recent phenomenon.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#23

Post by swagasaurus-rex »

swagasaurus-rex wrote: post #15

I've suspected as much would happen during the agricultural revolution, but I did not expect such a huge disparity. If the 51% male/female ratio did not change, then 16 out of 17 males must have either been killed, enslaved, or been left frustrated. This would imply a highly patriarchal society where the local king and his cronies are the only ones fed, and to whom you would sell your daughters to. The only other exp…

One other hypothesis I can think of is the advent of barbarian warfare. Many parts of the old testament details how brutal life was, where various tribes are constantly at war and conquering other tribes.

Even several generations of warfare, where each village sacked involved killing the men and abducting the women, would filter out y-chromosomes to see such a large disparity.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#24

Post by swagasaurus-rex »

ardit33 wrote: post #20
JeffL wrote: post #12

If you guys are interested in this stuff, I highly recommend "The Red Queen" by Matt Ridley. http://amazon.com/Red-Queen-Evolution-Human-Nature/dp/006055...

This is a great passage from the Red Queen, that might explain what was happening at the time: In the ancient empire of the Incas, sex was a heavily regulated industry. The sun-king Atahualpa kept fifteen hundred women in each of many “houses of virgins” throughout his kingdom. They were selected for their beauty and were rarely chosen after the age of eight—to ensure their virginity. But they did not all remain virg…

Killing the llamas is one step too far.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#25

Post by Mikeb85 »

Not particularly surprising. In the ancient world, men were often killed in various ways (conflict, hunting accidents) or enslaved so the gender ratio was quite skewed.

I mean, typical ancient warfare meant you attack a town, kill/enslave all the men and boys, rape all the women, and ensure your culture's dominance over them for the next generation or two...

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#26

Post by Balgair »

swagasaurus-rex wrote: post #15

I've suspected as much would happen during the agricultural revolution, but I did not expect such a huge disparity. If the 51% male/female ratio did not change, then 16 out of 17 males must have either been killed, enslaved, or been left frustrated. This would imply a highly patriarchal society where the local king and his cronies are the only ones fed, and to whom you would sell your daughters to. The only other exp…

Not necessarily. There are a lot of things that the article left out. Number 1 is that the Y chromosome is about 25% of the size of the X chromosomes and is also the fastest evolving portion of the human genome. Since this was a DNA based study, you have to control for this as well. I assume they have, but I don't know for certain. Additionally, aneuploidy (XXY, YYX, etc) may also account for some differences along with chimeric (2+ genomes per person due to fraternal twin merging in womb) anomalies. You also have to control for outliers such as Ghengis Khan and those types of mass rape and pillaging, as he has skewed the statistics a fair bit.

Still, if they controlled for all this, it is an AMAZING finding. That only 6% of males will reproduce is fantastical, especially within an agrarian society. I would love to know of other mammalian species that have such low reproductive rates compared to females.

https://en.wikipedia.org/wiki/Y_chromosome

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#27

Post by ManFromUranus »

Houshalter wrote: post #11
Fuxy wrote: post #2

Makes perfect sense to me. If you look at our culture now there is always that one male all the females in a group tend to go for. Same for males there's always that 1 mega hotie you want to meet. The only difference is even average females can have any guy they want while the same doesn't apply to guys. The advent of agriculture gave females the ability to support their children more easily without the help of males…

Right. This is not a new theory. It's well known that evolution tends to favor polygamy where females are more selective and males are more promiscuous. What's interesting is that this apparently started after agriculture rather than before. I had previously thought that maybe hunter gatherers practiced polygamy but it faded away as we become more agricultural. Also 17 females to 1 male is pretty absurd. Even if you…

>I had previously thought that maybe hunter gatherers practiced polygamy but it faded away as we become more agricultural.

I would have thought otherwise, there is very little incentive for you to labour for the tribe if you have no skin in the game, so to speak. So they would give you a wife otherwise, why fight for them? Why hunt? Why do anything to benefit anyone other than yourself? Since you have nothing to lose, you can even steal from them since no one you care about suffers.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#28

Post by ll123 »

undersuit wrote: post #19
ll123 wrote: post #4

The invention of monogamy is what brought about the 4-5 female to male reproduction ratio.

What do you mean by that?

Under monogamy, women who previously would have become part of a powerful man's harem now reproduced with a man who previously would not have reproduced, therefore reducing the female/male reproduction ratio.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#29

Post by netcan »

swagasaurus-rex wrote: post #15

I've suspected as much would happen during the agricultural revolution, but I did not expect such a huge disparity. If the 51% male/female ratio did not change, then 16 out of 17 males must have either been killed, enslaved, or been left frustrated. This would imply a highly patriarchal society where the local king and his cronies are the only ones fed, and to whom you would sell your daughters to. The only other exp…

All of these seem possible, to some extant for humans. First, war kills males. A lot of war could potentially kill the majority of males.

Second, infanticide exists within the historical record. SO does slavery, castration, polygamy etc. It doesn't seem far fetched to imagine a highly polygamous society where the majority of men are denied partners by one or more of these.

Re: Analysis of DNA uncovers a rough dating scene after the advent of agriculture

#30

Post by dragonwriter »

undersuit wrote: post #19
ll123 wrote: post #4

The invention of monogamy is what brought about the 4-5 female to male reproduction ratio.

What do you mean by that?

There are a number of factors (particularly in premodern societies) that produce the imbalance, but polygyny particularly exacerbates the imbalance (and, from a pre-existing state of polygyny, then, monogamy reduces it) because polygyny means that the most successful males are each able, in their reproductive prime, to secure, with social support, exclusive reproductive access to multiple of the most desirable females, which increases the expected ratio of females successfully reproducing in that generation to the number of males successfully reproducing.

(Because of the biology of reproduction, this would seem likely to be the case even if, in institutional terms, the practice of polygyny was balanced by equal practice of polyandry, but historically that wasn't the case anyway.)

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