5 ms·

I have a pet (non-scientific) theory/query. Wouldn't such prolonged & sustained periods of female foeticide eventually cause the human body to mutate...and stop

by RaSoJo 7y ago

I have a pet (non-scientific) theory/query. Wouldn't such prolonged & sustained periods of female foeticide eventually cause the human body to mutate...and stop giving birth to the female sex entirely?

maeln 7y ago
This is not how mutation work [1]. If over several generation we "selected" women/men that "yield" more man then women (if such a thing is even coded in some genes which, as far as i know, we have no clue), we would slowly make this trait more frequent, increasing the issue. But this looks more like a bad sci-fi novel setup than something possible. [1] By that I mean: Mutation are not "created" by the environment. Evolution theory shows that we "select" mutation which will then become present in the majority of the population over several generation (provided that the mutation can be passed to offspring and yield a significant benefit that will last over several generation). Mutation happens all the time in your body, although, if i remember my high school biology class, most of them get "fixed". And mutation are only one of the many "tools" that help create diversity (chromosome recombination for example).
bryanrasmussen 7y ago
In the same way that if you clone a bunch of male dinosaurs to populate your amusement park but eventually "life finds a way", yes. Outside of fiction - no.
nordsieck 7y ago
> I have a pet (non-scientific) theory/query. Wouldn't such prolonged & sustained periods of female foeticide eventually cause the human body to mutate...and stop giving birth to the female sex entirely? It's the opposite, actually. It is evolutionarily favorable to give birth to the sex that is less numerous at sexual maturity. If female babies started dying, for whatever reason, the chance the average baby is female would gradually increase until the ratio of sexually mature females to males balanced out. Incidentally, this is presumably why there are slightly more males born than females [1] - males tend to die more frequently than females during childhood. ___ 1. https://en.wikipedia.org/wiki/Human_sex_ratio https://en.wikipedia.org/wiki/Human_sex_ratio > In humans, the natural ratio between males and females at birth is slightly biased towards the male sex, being estimated to be about 1.05[2] or 1.06[3] males/per female born.
- claudiawerner 7y ago
  >If female babies started dying, for whatever reason, the chance the average baby is female would gradually increase until the ratio of sexually mature females to males balanced out. Perhaps I'm missing something, but how does the human body have internal knowledge of the current gender ratio in society such that it will attempt to fix the ratio to balance?
  - nordsieck 7y ago
    > Perhaps I'm missing something, but how does the human body have internal knowledge of the current gender ratio in society such that it will attempt to fix the ratio to balance? It doesn't. This process happens strictly through natural selection. If average female fertility is F, the number of sexually mature females is f and the number of sexually mature males is m, then the average male fertility is F * f / m (each child is conceived by exactly one male and one female). This means that the less numerous sex has a higher fertility. It is not true that each child is equally likely to be male or female. Some parents are more predisposed to have male children and some parents are more predisposed to have female children. The parents predisposed to have more reproductively successful children will have their genes flourish - pushing the sex balance of new babies slightly in the corrective direction.
odiroot 7y ago
It's the males who are "mutated". The biological female is the original gender. Somewhere in the past our ancestors evolved a male counterpart to enable sexual reproduction.
- lm28469 7y ago
  > The biological female is the original gender. Weren't there no "gender" nor "female" before sexual reproduction evolved ?
  - odiroot 7y ago
    AFAIR from "The Red Queen", that means female genome is the original one (two XX chromosomes). We men have an Y chromosome which is a "depleted" or a lame chromosome that's encoding barely anything more than gender information. It's impossible to be a fully functional human with two YY chromosomes. And XXYY has their own set of problems.
belorn 7y ago
Looking at farming the answer is a significant No. Female calves are worth much more than male, and male chickens have so low value that they tend to be grind down to dust as soon their sex can be identified. If it was possible to raise cows and chickens that only gave female offspring it would cause a major change in agriculture. That it has not happen is a good indication that you can't selective breed for female offspring.
- bluGill 7y ago
  In the case of cows we can selectively breed for sex, 97% of dairy calfs are females, the 3% males are mix of particularly good mothers that they want to pass genes on from, and cases where the sex selection failed. There is a large amount of data/science to select which mothers gets to pass their genes onto sons (which in turn pass their genes onto thousands of mothers). This works in part because most cows are bred with AI - bulls are dangerous and so nobody wants them if they can avoid it. The above is numbers from one dairy farm I know of with ~3000 cows. I'm sure each farm is different.
  - belorn 7y ago
    I did not know that you could buy (patented) cow semen that is sorted to guarantee to produce only female cattle. I have family that operate a small-ish farm with several hundred cows and they certainly do not use such technology. It just a matter of fact for them that female calves are worth significant more and half the time you get females and the other half you get males. I will somehow try mention this in passing to them, through I suspect they do not do use artificial insemination which is a required step for this technology. I also wonder if in the future chicken farms will apply this when the technology get more refined, the patents expires and the cost of artificial insemination is cheaper than wasting time and resources on eggs only to then kill half the offsprings.

by RaSoJo 7y ago

maeln 7y ago

This is not how mutation work [1]. If over several generation we "selected" women/men that "yield" more man then women (if such a thing is even coded in some genes which, as far as i know, we have no clue), we would slowly make this trait more frequent, increasing the issue. But this looks more like a bad sci-fi novel setup than something possible. [1] By that I mean: Mutation are not "created" by the environment. Evolution theory shows that we "select" mutation which will then become present in the majority of the population over several generation (provided that the mutation can be passed to offspring and yield a significant benefit that will last over several generation). Mutation happens all the time in your body, although, if i remember my high school biology class, most of them get "fixed". And mutation are only one of the many "tools" that help create diversity (chromosome recombination for example).

bryanrasmussen 7y ago

In the same way that if you clone a bunch of male dinosaurs to populate your amusement park but eventually "life finds a way", yes. Outside of fiction - no.

nordsieck 7y ago

> I have a pet (non-scientific) theory/query. Wouldn't such prolonged & sustained periods of female foeticide eventually cause the human body to mutate...and stop giving birth to the female sex entirely? It's the opposite, actually. It is evolutionarily favorable to give birth to the sex that is less numerous at sexual maturity. If female babies started dying, for whatever reason, the chance the average baby is female would gradually increase until the ratio of sexually mature females to males balanced out. Incidentally, this is presumably why there are slightly more males born than females [1] - males tend to die more frequently than females during childhood. ___ 1. https://en.wikipedia.org/wiki/Human_sex_ratio https://en.wikipedia.org/wiki/Human_sex_ratio > In humans, the natural ratio between males and females at birth is slightly biased towards the male sex, being estimated to be about 1.05[2] or 1.06[3] males/per female born.

claudiawerner 7y ago
>If female babies started dying, for whatever reason, the chance the average baby is female would gradually increase until the ratio of sexually mature females to males balanced out. Perhaps I'm missing something, but how does the human body have internal knowledge of the current gender ratio in society such that it will attempt to fix the ratio to balance?
- nordsieck 7y ago
  > Perhaps I'm missing something, but how does the human body have internal knowledge of the current gender ratio in society such that it will attempt to fix the ratio to balance? It doesn't. This process happens strictly through natural selection. If average female fertility is F, the number of sexually mature females is f and the number of sexually mature males is m, then the average male fertility is F * f / m (each child is conceived by exactly one male and one female). This means that the less numerous sex has a higher fertility. It is not true that each child is equally likely to be male or female. Some parents are more predisposed to have male children and some parents are more predisposed to have female children. The parents predisposed to have more reproductively successful children will have their genes flourish - pushing the sex balance of new babies slightly in the corrective direction.

odiroot 7y ago

It's the males who are "mutated". The biological female is the original gender. Somewhere in the past our ancestors evolved a male counterpart to enable sexual reproduction.

lm28469 7y ago
> The biological female is the original gender. Weren't there no "gender" nor "female" before sexual reproduction evolved ?
- odiroot 7y ago
  AFAIR from "The Red Queen", that means female genome is the original one (two XX chromosomes). We men have an Y chromosome which is a "depleted" or a lame chromosome that's encoding barely anything more than gender information. It's impossible to be a fully functional human with two YY chromosomes. And XXYY has their own set of problems.

belorn 7y ago

Looking at farming the answer is a significant No. Female calves are worth much more than male, and male chickens have so low value that they tend to be grind down to dust as soon their sex can be identified. If it was possible to raise cows and chickens that only gave female offspring it would cause a major change in agriculture. That it has not happen is a good indication that you can't selective breed for female offspring.

bluGill 7y ago
In the case of cows we can selectively breed for sex, 97% of dairy calfs are females, the 3% males are mix of particularly good mothers that they want to pass genes on from, and cases where the sex selection failed. There is a large amount of data/science to select which mothers gets to pass their genes onto sons (which in turn pass their genes onto thousands of mothers). This works in part because most cows are bred with AI - bulls are dangerous and so nobody wants them if they can avoid it. The above is numbers from one dairy farm I know of with ~3000 cows. I'm sure each farm is different.
- belorn 7y ago
  I did not know that you could buy (patented) cow semen that is sorted to guarantee to produce only female cattle. I have family that operate a small-ish farm with several hundred cows and they certainly do not use such technology. It just a matter of fact for them that female calves are worth significant more and half the time you get females and the other half you get males. I will somehow try mention this in passing to them, through I suspect they do not do use artificial insemination which is a required step for this technology. I also wonder if in the future chicken farms will apply this when the technology get more refined, the patents expires and the cost of artificial insemination is cheaper than wasting time and resources on eggs only to then kill half the offsprings.