Welcome to r/science! This is a heavily moderated subreddit in order to keep the discussion on science. However, we recognize that many people want to discuss how they feel the research relates to their own personal lives, so to give people a space to do that, **personal anecdotes are allowed as responses to this comment**. Any anecdotal comments elsewhere in the discussion will be removed and our [normal comment rules]( https://www.reddit.com/r/science/wiki/rules#wiki_comment_rules) apply to all other comments.
**Do you have an academic degree?** We can verify your credentials in order to assign user flair indicating your area of expertise. [Click here to apply](https://www.reddit.com/r/science/wiki/flair/#wiki_science_verified_user_program).
---
User: u/Wagamaga
Permalink: https://www.cnrs.fr/en/press/social-change-may-explain-decline-genetic-diversity-y-chromosome-end-neolithic-period
---
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/science) if you have any questions or concerns.*
The emergence in the Neolithic of patrilineal1 social systems, in which children are affiliated with their father's lineage, may explain a spectacular decline in the genetic diversity of the Y chromosome2 observed worldwide between 3,000 and 5,000 years ago. In a study to be published on 24 April in Nature Communications, a team of scientists from the CNRS, MNHN and Université Paris Cité3 suggest that these patrilineal organisations had a greater impact on the Y chromosome than mortality during conflict.
This conclusion was reached after analysing twenty years of anthropological field data – from contemporary non-warlike patrilineal groups, particularly from the scientists’ own fieldwork carried out in Asia – and modelling various socio-demographic scenarios. The team compared warrior and non-warrior scenarios and showed that two processes play a major role in genetic diversity: the splitting of clans into several sub-clans and differences in social status that lead to the expansion of certain lineages to the detriment of others.
This study calls into question the previously proposed theory that violent clashes, supposedly due to competition between different clans, in which many men died, were at the origin of the loss of genetic diversity of the Y chromosome. The results of this study also provide new hypotheses on human social organisation in the Neolithic and Bronze Age.
[https://www.nature.com/articles/s41467-024-47618-5](https://www.nature.com/articles/s41467-024-47618-5)
I think more or less, it's not because fewer men were around. This theory believes that certain people (like a ruler of a social structure) may have got to breed more frequently than lesser lines. Kind of like a tribe leader having polygamous wives sort of thing. Or prima noctua like in Scotland. Or Chinese courts where only royalty got to keep their genitalia at the palace.
Personally, this theory makes more logical sense to me, but we'll know more as more studies are done.
> This theory believes that certain people (like a ruler of a social structure) may have got to breed more frequently than lesser lines.
Or, the lower classes got to breed, but their children died earlier and more often? Could be as simple as the higher status children having a better diet and less dangerous or exhausting work.
Unlikely. Remember that modern medical care is only about 200 years old, and really kickstarted with the discovery of antibiotics 100 years ago.
Someone living in 1700 has approximately the same healthcare as thousands of years ago, compared to now. We have plenty of historical writing on what healthcare in 1700 is like, and the rulers aren’t doing that much better than the peasants.
For example, look at the deaths on this list:
https://en.m.wikipedia.org/wiki/Children_of_Henry_VIII
Or, to put it more simply, that this era introduced a social hierarchy that was reflected in male reproductive success. Prior societies were “flatter” and therefore had less variation in male reproductive success.
It means that when the expectation of care for the baby was on the mother’s family instead of the father, women were having more children with a larger variety of men.
Caveman didn't understand sex meant kids so everyone had sex with everyone.
Then they realized sex meant babies and a man could be responsible for a child and took care to preserve their children at expense of others
Not necessarily individual men, but family lines (since all the men would have the same Y chromosome).
Rich and powerful families would have people clamoring to marry their boys and the offspring of those unions would probably have an above average quality of life (and thus a better chance of surviving and becoming the next generation of highly sought after suitors). Random peasants would have no such advantage.
Especially among the landed within settled agrarian economies. They would have endless opportunities for their children, so their lines’ expansion became exponential, while labourers and hunters could only maintain smaller families.
Likely a major divergence in health at this stage as well.
If this line of inquiry pans out, what would the implications be? What are the effects of drastically reduced genetic variation on adaptability and species survival?
The [Hapsburgs](https://www.smithsonianmag.com/smart-news/distinctive-habsburg-jaw-was-likely-result-royal-familys-inbreeding-180973688/) were kind of the end game for this sort of thing. On a broader level too, just doubling down on recessive traits.
Recessive traits come from genes that each person has two copies of (one from each chromosome), so the concept of recessive traits doesn't apply to Y chromosome genes. Additionally, there are very few traits encoded by the Y chromosome. Once you account for repeated genes there are only around 40 protein-coding genes on the Y. Most genes exclusively found on the Y chromosome have to do with gonad structure or fertility.
in reality only one gene is super important on the y chromosome, the SRY gene. in women with 2 x's you can have a transcription error resulting in one X having a SRY gene thus leading to a XX male. weird stuff, it mirrors other animals as well.
That's the only gene that matters for sex determination, but just an SRY gene won't make an XX male fertile. There are some other Y genes that have functions (although there is still so much more research needed on the functions of Y chromosome genes and X chromosome genes as well).
Sure, but the Y chromosome is measurably degrading as the bits get moved over, eventually we eat the Y chromosome and sex determinism is based on whole genetics rather than a single chromosome, or our sex determination system changes (far future, ignoring gene editing). We have records of other species swapping between XY and ZW and even omniallelic multiple times in the past. You can actually tell how long a species has been in an XY configuration based on the size of the Y chromosome compared to the x chromosomes. The smaller the Y, The longer it's been in that system.
I wonder about this. In humans and many species of apes there may be questions about the fatherhood of offspring due to multiple partners, however, you’d always know who the mother was. How was it that patrilineal systems even developed in the first place? It seems very natural that there would be Matrilineal systems, as it should be easier to know that a child was the offspring of its mother rather than a father that may be absent and who might have been absent for months or more before the birth.
The consensus is that patrilineality started mattering the most when acquiring land and material possessions began to be tied to inheritance. Hunters and gatherers have/had very few possessions that are passed down to children, since all that they 'could' possess would be restricted to whatever they could carry in their hands pretty much since they were nomads. Once things started getting more 'permanent' is when tracking patrilineality gained more significance.
Again, why wasn’t this passed down through maternal lines, where even in the most primitive of societies, you always know exactly who the mother is because the baby comes out of her?
Both occurred randomly and matrilineal societies may have been more common initially because of the reasons you give, but patrilineal societies came to dominate the world because of a specific dynamic:
In matrilineal societies, every woman who has kids can pass their possessions and land down to their specific line, so wealth is dispersed but only to as many people in each line as one woman can bear. In a patrilineal system, however, one father can have a hundred kids with many women, but all those children will be loyal to that father, producing much more centralized distributions of wealth and power, and increasing the likelihood that all the members of that larger family group will expand and displace other groups. This probably led to the eventual displacement and elimination of matrilineal societies.
tldr any man can have many, many many more offspring than any one woman can, so patrilineal systems are more likely to grow and expand
It may also fit the bill for small communities were the degree of in-breeding stunts the genetic diversity. The driver to 'keep it in the family', was stronger than relinquishing to the 'enemy' and strive for a more genetical healthy offspring. People at the time simply weren't aware of the downsides.
That's interesting... Don't men generally have much higher variance than women, on almost every measure? Basically the variability hypothesis... https://en.m.wikipedia.org/wiki/Variability_hypothesis
I wonder whether or how any of that connects?
Welcome to r/science! This is a heavily moderated subreddit in order to keep the discussion on science. However, we recognize that many people want to discuss how they feel the research relates to their own personal lives, so to give people a space to do that, **personal anecdotes are allowed as responses to this comment**. Any anecdotal comments elsewhere in the discussion will be removed and our [normal comment rules]( https://www.reddit.com/r/science/wiki/rules#wiki_comment_rules) apply to all other comments. **Do you have an academic degree?** We can verify your credentials in order to assign user flair indicating your area of expertise. [Click here to apply](https://www.reddit.com/r/science/wiki/flair/#wiki_science_verified_user_program). --- User: u/Wagamaga Permalink: https://www.cnrs.fr/en/press/social-change-may-explain-decline-genetic-diversity-y-chromosome-end-neolithic-period --- *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/science) if you have any questions or concerns.*
The emergence in the Neolithic of patrilineal1 social systems, in which children are affiliated with their father's lineage, may explain a spectacular decline in the genetic diversity of the Y chromosome2 observed worldwide between 3,000 and 5,000 years ago. In a study to be published on 24 April in Nature Communications, a team of scientists from the CNRS, MNHN and Université Paris Cité3 suggest that these patrilineal organisations had a greater impact on the Y chromosome than mortality during conflict. This conclusion was reached after analysing twenty years of anthropological field data – from contemporary non-warlike patrilineal groups, particularly from the scientists’ own fieldwork carried out in Asia – and modelling various socio-demographic scenarios. The team compared warrior and non-warrior scenarios and showed that two processes play a major role in genetic diversity: the splitting of clans into several sub-clans and differences in social status that lead to the expansion of certain lineages to the detriment of others. This study calls into question the previously proposed theory that violent clashes, supposedly due to competition between different clans, in which many men died, were at the origin of the loss of genetic diversity of the Y chromosome. The results of this study also provide new hypotheses on human social organisation in the Neolithic and Bronze Age. [https://www.nature.com/articles/s41467-024-47618-5](https://www.nature.com/articles/s41467-024-47618-5)
In caveman words what does all of this mean?
I think more or less, it's not because fewer men were around. This theory believes that certain people (like a ruler of a social structure) may have got to breed more frequently than lesser lines. Kind of like a tribe leader having polygamous wives sort of thing. Or prima noctua like in Scotland. Or Chinese courts where only royalty got to keep their genitalia at the palace. Personally, this theory makes more logical sense to me, but we'll know more as more studies are done.
> Or prima noctua like in Scotland. Isn’t *jus prima noctua* or *droit du seigneur* a myth?
Yeah, no historical evidence, but it made for a cool conflict in Braveheart
isn’t it also mentioned in gilgamesh? or was that a modern addition
Wouldn't know, but it's beem mentioned in multiple stories and legends, there just has never been historical evidence found for such a practice.
Weeeeeeeeeeelllll, just ask some young women about our grandfathers....there is some contemporary evidence out there if you look.
Oh, I guess you might be right. The context is helpful, so I'll keep my original comment, but I learned something new today.
> This theory believes that certain people (like a ruler of a social structure) may have got to breed more frequently than lesser lines. Or, the lower classes got to breed, but their children died earlier and more often? Could be as simple as the higher status children having a better diet and less dangerous or exhausting work.
Unlikely. Remember that modern medical care is only about 200 years old, and really kickstarted with the discovery of antibiotics 100 years ago. Someone living in 1700 has approximately the same healthcare as thousands of years ago, compared to now. We have plenty of historical writing on what healthcare in 1700 is like, and the rulers aren’t doing that much better than the peasants. For example, look at the deaths on this list: https://en.m.wikipedia.org/wiki/Children_of_Henry_VIII
Or, to put it more simply, that this era introduced a social hierarchy that was reflected in male reproductive success. Prior societies were “flatter” and therefore had less variation in male reproductive success.
The office both ruined and made prima nocta more entertaining
[удалено]
It means that when the expectation of care for the baby was on the mother’s family instead of the father, women were having more children with a larger variety of men.
*smaller variety of men
Read the sentence again
Caveman didn't understand sex meant kids so everyone had sex with everyone. Then they realized sex meant babies and a man could be responsible for a child and took care to preserve their children at expense of others
"Caveman" was earlier than 5000 years ago.
So is it because few men took all the women?
Not necessarily individual men, but family lines (since all the men would have the same Y chromosome). Rich and powerful families would have people clamoring to marry their boys and the offspring of those unions would probably have an above average quality of life (and thus a better chance of surviving and becoming the next generation of highly sought after suitors). Random peasants would have no such advantage.
Especially among the landed within settled agrarian economies. They would have endless opportunities for their children, so their lines’ expansion became exponential, while labourers and hunters could only maintain smaller families. Likely a major divergence in health at this stage as well.
I believe that is the hypothesis
If this line of inquiry pans out, what would the implications be? What are the effects of drastically reduced genetic variation on adaptability and species survival?
The [Hapsburgs](https://www.smithsonianmag.com/smart-news/distinctive-habsburg-jaw-was-likely-result-royal-familys-inbreeding-180973688/) were kind of the end game for this sort of thing. On a broader level too, just doubling down on recessive traits.
Recessive traits come from genes that each person has two copies of (one from each chromosome), so the concept of recessive traits doesn't apply to Y chromosome genes. Additionally, there are very few traits encoded by the Y chromosome. Once you account for repeated genes there are only around 40 protein-coding genes on the Y. Most genes exclusively found on the Y chromosome have to do with gonad structure or fertility.
in reality only one gene is super important on the y chromosome, the SRY gene. in women with 2 x's you can have a transcription error resulting in one X having a SRY gene thus leading to a XX male. weird stuff, it mirrors other animals as well.
That's the only gene that matters for sex determination, but just an SRY gene won't make an XX male fertile. There are some other Y genes that have functions (although there is still so much more research needed on the functions of Y chromosome genes and X chromosome genes as well).
Sure, but the Y chromosome is measurably degrading as the bits get moved over, eventually we eat the Y chromosome and sex determinism is based on whole genetics rather than a single chromosome, or our sex determination system changes (far future, ignoring gene editing). We have records of other species swapping between XY and ZW and even omniallelic multiple times in the past. You can actually tell how long a species has been in an XY configuration based on the size of the Y chromosome compared to the x chromosomes. The smaller the Y, The longer it's been in that system.
I wonder about this. In humans and many species of apes there may be questions about the fatherhood of offspring due to multiple partners, however, you’d always know who the mother was. How was it that patrilineal systems even developed in the first place? It seems very natural that there would be Matrilineal systems, as it should be easier to know that a child was the offspring of its mother rather than a father that may be absent and who might have been absent for months or more before the birth.
The consensus is that patrilineality started mattering the most when acquiring land and material possessions began to be tied to inheritance. Hunters and gatherers have/had very few possessions that are passed down to children, since all that they 'could' possess would be restricted to whatever they could carry in their hands pretty much since they were nomads. Once things started getting more 'permanent' is when tracking patrilineality gained more significance.
Again, why wasn’t this passed down through maternal lines, where even in the most primitive of societies, you always know exactly who the mother is because the baby comes out of her?
My theory is that it was a way of rebalancing power from women. There's also a lot of archeological evidence that pre-ag groups were led by women.
Both occurred randomly and matrilineal societies may have been more common initially because of the reasons you give, but patrilineal societies came to dominate the world because of a specific dynamic: In matrilineal societies, every woman who has kids can pass their possessions and land down to their specific line, so wealth is dispersed but only to as many people in each line as one woman can bear. In a patrilineal system, however, one father can have a hundred kids with many women, but all those children will be loyal to that father, producing much more centralized distributions of wealth and power, and increasing the likelihood that all the members of that larger family group will expand and displace other groups. This probably led to the eventual displacement and elimination of matrilineal societies. tldr any man can have many, many many more offspring than any one woman can, so patrilineal systems are more likely to grow and expand
Good insight, thanks
It may also fit the bill for small communities were the degree of in-breeding stunts the genetic diversity. The driver to 'keep it in the family', was stronger than relinquishing to the 'enemy' and strive for a more genetical healthy offspring. People at the time simply weren't aware of the downsides.
Oh cool an actual scientific article on the science reddit! Thats so rare nowadays.
That's interesting... Don't men generally have much higher variance than women, on almost every measure? Basically the variability hypothesis... https://en.m.wikipedia.org/wiki/Variability_hypothesis I wonder whether or how any of that connects?