Why ratio of male vs female population of the world remains 50:50 always?
I think reproduction and the rules of probability would be the reason for that. We have (basically) two different genders in our species male and female. XX and XY. That means it’s a fifty-fifty chance at any given time that a child born will be male or female. Add in the some of modern day equality of treatment for genders – that means people are less likely nowadays to do barbaric things like leaving their baby daughters out to die of exposure because they were of less value than the male babies – and it’s easy to see how the ratio fluctuates around the same numbers.
