How is the balance between boys and girls maintained?

[lightblue]

Meiosis... An egg cell will always have an X chromosome, a sperm cell has a 50/50 chance of getting an X or Y chromosome, due to independent assortment. XX makes a girl, XY a boy. Seeing as kids are the product of the fusion of an egg and sperm cell this explains why the birth rate of either sex is approx even.

[Kidlicious]

That doesn't explain how we have such continuous and uniform balance in nature.

[giblets]

Can't we then have generations of mostly boys or mostly girls? My question is why is the balnce maintained?

You know that the chances of that happening would be extremely low, right?

[Hauldren Collider]

No, he doesn't, because he doesn't understand probability.

[Combat Ingrid]

Every sperm is sacred

[giblets]

Okay, if we assumed for a second that there's a 50/50 chance of having a boy or a girl, it looks like in a population with 1000 children the chances that at least 55% of them would be boys are .069587% so I really don't understand why we don't see any large human populations that are mostly boys or mostly girls!!!!11!!1!

[Kidlicious]

In every country in the world there are slightly more boys born than girls. The world ratio is 1.07. No country in the world differs by more than 0.06.

[kentonio]

Girls live longer, which presumably balances that out somewhat.

[giblets]

Okay guys so why have I lasted so long without getting struck by lightning? Maybe God is protecting me?

[Kidlicious]

Okay, if we assumed for a second that there's a 50/50 chance of having a boy or a girl, it looks like in a population with 1000 children the chances that at least 55% of them would be boys are .069587% so I really don't understand why we don't see any large human populations that are mostly boys or mostly girls!!!!11!!1!

Well yeah. I haven't checked your math but there are no countries with that many boys.

[Kidlicious]

Girls live longer, which presumably balances that out somewhat.

Just talking about births here.

[Dauphin]

Okay, if we assumed for a second that there's a 50/50 chance of having a boy or a girl,

There isn't....

[giblets]

Well yeah. I haven't checked your math but there are no countries with that many boys.

Weird, it couldn't have anything to do with the much larger population of a typical country.

[Dauphin]

Just talking about births here.

Why birth, and not say reproductive age, which would be more relavent for evolutionary considerations, as I understand it.

[BeBMan]

In a related question, why do they have so many people in India and China, but not in Canada??? If that doesn't prove god being responsible then I don't know.