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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

#61

Earlier quoted context omitted.

War has rarely had a significant effect on populations, certainly nothing like the effect of disease. Although many men in the ancient world died by violence (as they do in pre-political societies and failed states today) killing with stone tools is pretty difficult and dangerous, so constant warfare that killed enough men to account for a 17:1 reproductive ratio for long enough to leave its mark today would have mad…

> and a 17:1 ratio suggests a system that was capable of actually excluding, not just nominally excluding, the vast majority of men from reproducing. It doesn't actually imply that, because many of them could have reproduced, but not had offspring that survived to reproduce for sufficient numbers of generations. Modern DNA won't distinguish that from didn't reproduce. So, the fact that the vast majority of men of the…

That's a fair point.

Thinking about limit-case scenarios, if the bottleneck lasted long enough, this could be a matter of 5% of the men having 1+epsilon male offspring and 95% having 1-epsilon male offspring. For even relatively modest values of epsilon that would give quite a large deviation in the population, given enough time.

The article suggests this went on for about 2000 years (8000-6000 BCE) which is 100 generations, so if epsilion was 0.05 then the favoured class would have fathered 99.5% of the male population at the end of that time (most of whom would have fallen into the unfavoured class over time, of course.) Because all women reproduced (more or less) I think they just fall out of the calculation.

So you are correct.

[Edit: the article actually suggests it was as much as 4000 years, so an even smaller disparity could work.]

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

#62

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…

You saw this coming? Just how old are you?

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

#64

In populations studies at all scales, Adam is more recent than Eve. 10 years ago, I read it was Eve 120,000 years ago and Adam 60,000 years ago for the out of Africa theory.

What do Adam and Eve refer to in this context? Also, what do you mean by "more recent"?

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

#65
post #64

In populations studies at all scales, Adam is more recent than Eve. 10 years ago, I read it was Eve 120,000 years ago and Adam 60,000 years ago for the out of Africa theory.

What do Adam and Eve refer to in this context? Also, what do you mean by "more recent"?

I assume: http://en.wikipedia.org/wiki/Mitochondrial_Eve

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

#66
post #20

Earlier quoted context omitted.

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.

Thanks for a good laugh

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

#67
post #29

Earlier quoted context omitted.

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.

War has rarely had a significant effect on populations, certainly nothing like the effect of disease. Although many men in the ancient world died by violence (as they do in pre-political societies and failed states today) killing with stone tools is pretty difficult and dangerous, so constant warfare that killed enough men to account for a 17:1 reproductive ratio for long enough to leave its mark today would have mad…

You don't have to survive long to pass on your genes. You don't need to make it past 30 to produce a big range of offspring.

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

#68
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…

Agriculture created surplus which meant that someone could feed a larger family.

If you are a hunter gatherer you need to be a very good one to support more than one wife, even if you are the chief.

With surplus generated by agriculture, spare time can be spent innovating to increase the surplus. Inequal skills in building a personal surplus - whether by conquest, investment or thrift - means that some people get richer. Richer men gain power and are able to not only attract more females but rewrite the rules to make it so.

A few generations of this and you change the population considerably.

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

#69
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.

Upon Googling, I think this comes from genetic analysis which suggests that people alive today have 4-5x as many female ancestors as male.

I don't know if this statistic is actually limited by "recent history" or not.

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

#70
post #20

Earlier quoted context omitted.

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.

In those times, they really wanted to get the point across.
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