system
Given the following post, respond as if you're commenting on Reddit:
human
Is the ratio between females and males similar between all primates?

Particularly interesting would be a) at birth and b) at "breeding age" (don't know how you say for people).

**Edit:** To clarify, I mean a ratio in the number of specimens, and I'm talking about the few-percent difference that I've heard about in humans.
gpt
There's a good theoretical argument why the male/female ratio should be close to 50/50 in any species.

Suppose the ratio were different, let's say 9 females to 1 male. Imagine that a random mutation caused one of the genders to be more probable to be born than the other. That mutation would spread through the gene pool, increasing the ratio.

In that scenario, the most increase the females could get from a mutation would be from 0.9 to 1.0, a 10% gain, while males could go from 0.1 to 1.0, a 1000% gain. A random change will always benefit the gender with fewer representatives, which drives the ratio to 50/50.