
Analysis of DNA uncovers a rough dating scene after the advent of agriculture - pepys
http://www.psmag.com/nature-and-technology/17-to-1-reproductive-success
======
swagasaurus-rex
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
explanation would be mass infanticide of males, but to see this in multiple
regions is suspect.

"It wasn't like there was a mass death of males. They were there, so what were
they doing?" The article raises a very good question. In all places studied,
agriculture must have favored a highly stratified society.

~~~
Balgair
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](https://en.wikipedia.org/wiki/Y_chromosome)

~~~
brazzy
> I would love to know of other mammalian species that have such low
> reproductive rates compared to females.

Some species of deer probably match it.

~~~
Balgair
True! Then it seems that the early agrarian humans had more of a herd
mentality or reproductive structure of winner take all. Do other apes or
monkeys have similar breeding structures? Fascinating stuff.

~~~
brazzy
Gorillas form harem-like groups, but they're not as large, 3 to 6 females per
male (often the groups have multiple related males). Chimps have dominant
males, but females can and often do have sex with other males in the group.
Bonobos are just ridiculously promiscous :)

I just found a book called "Human Natures: Genes, Cultures, and the Human
Prospect" which claims that southern elephant seals have harems of 48 females
on average O_O - that's probably the record among mammals.

------
JeffL
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...](http://amazon.com/Red-Queen-Evolution-Human-
Nature/dp/0060556579/ref=sr_1_2?ie=UTF8&qid=1426700896)

~~~
ardit33
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 virgins for long: They were the emperor’s concubines. Beneath
him, each rank of society afforded a harem of a particular legal size. Great
lords had harems of more than seven hundred women. “Principal persons” were
allowed fifty women; leaders of vassal nations, thirty; heads of provinces of
100,000 people, twenty; leaders of 1,000 people, fifteen; administrators of
500 people, twelve; governors of 100 people, eight; petty chiefs over 50 men,
seven; chiefs of 10 men, five; chiefs of 5 men, three. That left precious few
for the average male Indian whose enforced near-celibacy must have driven him
to desperate acts, a fact attested to by the severity of the penalties that
followed any cuckolding of his seniors. If a man violated one of Atahualpa’s
women, he, his wife, his children, his relatives, his servants, his fellow
villagers, and all his lamas would be put to death, the village would be
destroyed, and the site strewn with stones. As a result, Atahualpa and his
nobles had, shall we say, a majority holding in the paternity of the next
generation. They systematically dispossessed less privileged men of their
genetic share of posterity. Many of the Inca people were the children of
powerful men. In the kingdom of Dahomey in West Africa, all women were at the
pleasure of the king. Thousands of them were kept in the royal harem for his
use, and the remainder he suffered to “marry” the more favored of his
subjects. The result was that Dahomean kings were very fecund, while ordinary
Dahomean men were often celibate and barren. In the city of Abomey, according
to one nineteenth-century visitor, “it would be difficult to find Dahomeans
who were not descended from royalty.” The connection between sex and power is
a long one.

~~~
swagasaurus-rex
Killing the llamas is one step too far.

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

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seokranik
Since a lot of early civilizations seemed to be very slave heavy I wonder if
that had anything to do with it. Agriculture requires more labour which leads
to more slaving. Male slaves would work the fields with less of a chance for
reproduction, and the landowners/slaveowners would have their pick of the
female slaves.

~~~
tormeh
Very good. That's probably an important factor.

------
noiv
Just started reading Harari's brief history of humankind and this gem
perfectly fits in the rather unsettling story of our genetic pool. It is no
longer the natural environment setting the conditions for who's fit to
survive/chosen for reproduction but the present human culture which in turn is
just the result of the previous.

If I had to choose an algorithm as an analogy, I'd say it is a recursion
waiting for stack overflow. :)

~~~
asdkl234890
We are a very social species, the culture we create is our natural
environment.

------
littletimmy
It sounds like a persistent theme through history is that a very few people at
the top had a Lot of power, and most men and all women were oppressed.

Feminists, take note: men are not privileged. Just those who were privileged
were men. The fight must be against the few at the top.

~~~
victorhn
There will be always a few at the top, hierarchies among humans will always
exist due to natural differences.

------
sloreti
"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.

~~~
swagasaurus-rex
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.

~~~
saalweachter
You still get at least an element of this with pretty recent til-death-do-us-
part versions of serial monogamy: Gauss, for instance, had two wives, marrying
a friend of his first wife after she died, and had children with both of them.

(I'd be surprised if serial monogamy alone were enough to get a 4:1 ratio, but
you can definitely get > 1:1 ratios out of it.)

------
Fuxy
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 and the more desirable males could have
more offspring with so much food available.

Basically less females had to settle for second best to have offspring.

~~~
Houshalter
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 look at cultures that
practiced polygamy in recent history it wasn't to that extent. And even when
it was practiced, it wasn't necessarily common except in the very upper class,
so the average female to male ratio would have been more reasonable.

We can only speculate to what degree this might have shaped our (recent)
evolution. That's a huge selective pressure on males to have traits that would
lead to them being the local king or whatever they were. And everyone alive
today would be descended from those people.

~~~
ManFromUranus
>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.

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rhema
This is not my research area. However, I can't help but the results seem to
radical to me. The dip in male diversity seems far too synchronized among so
many different regions / cultures. Are there examples in recorded history of
sudden reductions in male diversity that lasted for multiple generations?

~~~
dalke
[http://blogs.discovermagazine.com/gnxp/2010/08/1-in-200-men-...](http://blogs.discovermagazine.com/gnxp/2010/08/1-in-200-men-
direct-descendants-of-genghis-khan/) :

> ~10% of the men who reside within the borders of the Mongol Empire as it was
> at the death of Genghis Khan may carry his Y chromosome, and so ~0.5% of men
> in the world, about 16 million individuals alive today, do so. Since 2003
> there have been other cases of “super-Y” lineages. For example the Manchu
> lineage and the Uí Néill lineage. The existence of these Y chromosomal
> lineages, which have burst upon the genetic landscape like explosive stars
> sweeping aside all other variation before them, indicates a periodic it
> “winner-take-all” dynamic in human genetics more reminiscent of hyper-
> polygynous mammals such as elephant seals. As we do not exhibit the sexual
> dimorphism which is the norm in such organisms, it goes to show the
> plasticity of outcome due to the flexibility of human cultural forms.

------
deciplex
> Another member of the research team, a biological anthropologist,
> hypothesizes that somehow, only a few men accumulated lots of wealth and
> power, leaving nothing for others.

This line cracked me up.

Yes, "somehow" indeed. Quite a mystery we have on our hands here!

------
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...

~~~
tormeh
I have a hunch that this ancient way of warfare is still the optimal way to
destroy a culture and achieve total victory. Not that it's acceptable in any
way, but imagine if the US had done this in Iraq and Afghanistan. It is heart-
wrenching to think about, but I think it would have worked.

~~~
def_illiterate
An argument could probably be made that it worked fairly well in subduing East
Germany after WWII.

~~~
fsloth
I new that those things happened there but not that this was was so
widespread!
[http://en.wikipedia.org/wiki/Rape_during_the_occupation_of_G...](http://en.wikipedia.org/wiki/Rape_during_the_occupation_of_Germany)

"estimates of the numbers of German women raped by Soviet soldiers have ranged
up to 2 million"

------
robbrown451
Sounds to me like slavery. The women slaves had babies, the male slaves were
workers and soldiers.

In a way, it sort of sounds like a eusocial sort of society, like a bee colony
(but with the male female roles reversed). One reproducing male, many
reproducing females, many non-reproducing males.

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jrells
Fascinating stuff, I'd like to know more.

Does anyone know a better source?

I found the original article but sadly not freely available. This psmag.com
article is thin and the graph of the data is so small I can't read much off of
it. Google couldn't find any larger versions of the graph.

~~~
josu
Here:
[http://genome.cshlp.org/content/early/2015/03/13/gr.186684.1...](http://genome.cshlp.org/content/early/2015/03/13/gr.186684.114/suppl/DC1)

------
stillsut
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.

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

~~~
roywiggins
I assume:
[http://en.wikipedia.org/wiki/Mitochondrial_Eve](http://en.wikipedia.org/wiki/Mitochondrial_Eve)

------
ll123
The invention of monogamy is what brought about the 4-5 female to male
reproduction ratio.

~~~
undersuit
What do you mean by that?

~~~
dragonwriter
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.)

------
AhrowTway
\- Initial kings collect women like Pokemon.

\- No contraception. Much baby.

\- Many claims to throne in 14-18 years.

\- Claimants go to war with one another. Soldiers are invented, voluntary and
noble at first. Religious later. Can't do mass conscription from the common
man as he's working the essential farms.

\- Losers happen. Slavery is invented.

\- Slaves work the mines and other harsh labor, which allows for post-agrarian
activities and advanced economies.

\- King sits back and lets the the whole clusterfuck evolve in his favor.

A auto-catalytic male shortage. Easy peasy.

Inadvertently, I have just Twitterized the Old Testament.

------
andyl
My 16 yr old is interested in pursuing this field (not sure what to call it -
'Genetic Anthropology'?). Can anyone recommend online resources to help a
newbie get the lay of the land? Or in-person resources (talks, exhibits, clubs
etc.) near Palo Alto CA ??

~~~
CreRecombinase
I would say if Carlos Bustamante or Stephen Montgomery are ever giving a talk
to the public to check them out. They're both based out of Stanford Med, but
their research touches on tracing Human demographic history. If she's still
interested when applying for colleges, Harvard and The University of Chicago
should both be on her list.

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bengrunfeld
Eunuch's and harems. The rich and powerful males kept all their local women in
a harem and forced all the other competing males to become eunuchs. Not fun,
but it fits with the Monty Python version of history.... ;)

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yuashizuki
Its the same even today.

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ccvannorman
"somehow, only a few men accumulated lots of wealth and power, leaving nothing
for others"

Yeah, thank god we're past this as a species

~~~
phkahler
I thought it had been observed with monkeys or apes that in times of scarcity
they will share, but if you dump a whole truck load of bananas they will fight
over them. The rise of agriculture would be a similar time of plenty which may
be what triggered all the fighting and hoarding.

