I believe there's some evidence that the earlier a woman conceives in her cycle the more likely a boy is to be born (https://pubmed.ncbi.nlm.nih.gov/449885/). I'd imagine that when people are having sex more often e.g. post war or during an economic crash (the peak in the 70s) more women conceive early in the cycle and more boys are therefore born.
Why would more women conceive early in the cycle under those circumstances? Wouldn’t there just be more babies conceived across the whole cycle? I don’t understand why the ratio would change?
Be gentle with me, I’ve never been good at comprehending this sort of thing 👍😂
The theory is the hare and the tortoise: the XY male sperm versus the XX payload of the female sperm. The XY version swims fast but burns out and dies. The XX version swims slower, but can survive for perhaps days.
When ovulation occurs, the egg starts its journey to the womb and if copulation has occurred recently, the first successful sperm is more likely to be XY, but if the act was yesterday then the live sperm, still present, is more likely to be XX.
[Both I and my two children have managed to pull off the trick of having a boy and then a girl a couple of years later]
There's a phenomenon called the 'Returning Soldier effect' which has been observed for quite a while and seems to fit - though it seems the exact mechanism (genetic? hormonal? something else?) is still debated and unclear.
I believe there's some evidence that the earlier a woman conceives in her cycle the more likely a boy is to be born (https://pubmed.ncbi.nlm.nih.gov/449885/). I'd imagine that when people are having sex more often e.g. post war or during an economic crash (the peak in the 70s) more women conceive early in the cycle and more boys are therefore born.
Why would more women conceive early in the cycle under those circumstances? Wouldn’t there just be more babies conceived across the whole cycle? I don’t understand why the ratio would change?
Be gentle with me, I’ve never been good at comprehending this sort of thing 👍😂
The theory is the hare and the tortoise: the XY male sperm versus the XX payload of the female sperm. The XY version swims fast but burns out and dies. The XX version swims slower, but can survive for perhaps days.
When ovulation occurs, the egg starts its journey to the womb and if copulation has occurred recently, the first successful sperm is more likely to be XY, but if the act was yesterday then the live sperm, still present, is more likely to be XX.
[Both I and my two children have managed to pull off the trick of having a boy and then a girl a couple of years later]
There's a phenomenon called the 'Returning Soldier effect' which has been observed for quite a while and seems to fit - though it seems the exact mechanism (genetic? hormonal? something else?) is still debated and unclear.
https://en.wikipedia.org/wiki/Returning_soldier_effect
Thanks
I can’t vouch for accuracy necessarily but in this video Hannah Fry claims to address this
https://www.instagram.com/reel/C14oemLtcRl/?utm_source=ig_embed&ig_rid=da9300a2-fa57-448e-a674-610da2a648ed&ig_mid=049647D2-76A3-4B71-853C-B60B3706C28E