Q: âWhy do girls get their periods so much earlier than when modern society and common logic agrees they should be having babies (having sex)? It seems cruel and truly traumatic to make an immature 12 year old girl (or earlier) have to see herself bleed from such a personal place. Maybe evolution will shift this?â
We received this great question earlier today and did some research/digging to find the answer.Â
First thingâs first -- yes, menstruation and menarche (first period) can feel traumatic/scary (after all -- blood usually = danger/bad things) -- but hopefully by talking about it more itâll be less so.Â
Ok, onto the question at hand!
Everyone is different -- so some 12 year olds are more/less mature than others (just like some 14, 18, 30, or 65 year olds are more/less mature!). Why one young woman starts her period before another is a result of many factors, both biological (in her body) and environmental (outside of her body).Â
Your genetics can lead you to menstruate at a certain time, but so can your stress level, diet, and your home life.
For those who are interested in a headier answer, we found this interesting article on the topic in Psychology Today:
https://www.psychologytoday.com/blog/the-stone-age-mind/201202/why-are-girls-getting-their-periods-so-young
âWhen parental care is inconsistent, less sensitive, and more emotionally negative, children will develop insecure attachments and opportunistic mating strategies. This, researchers argue, translates to earlier onset of puberty and menarche (Belsky et al., 1991).â
âThe theory suggests that when Dad's not around, menarche is brought on by way of bio-signals that tell the body, âThis is an unstable environment,â or âThere's a shortage of males in the population.' In these scenarios, the evolutionary brain sees survival as less likely, and therefore speeds up the sexual maturation process.â
â...recent research has shown that the presence of a stepfather does accelerate menarche (Ellis, 2004; Ellis & Garber, 2000). But interestingly enough, the conclusion is reversed in girls who have supportive and invested stepfathers (Jaffee et al., 2003). â
âGirls who had insecure attachments to their mother achieved menarche earlier than girls who had secure attachments (Belsky, Houts, & Fearon, 2010). ...if Mom is harsh, then it would be in a girlâs evolutionary interest to mature faster. This way, she could find a mate that would take care of her.â
But, again, it could simply be a genetic thing, so donât start drawing conclusions about the state of a young womanâs home/parenting based on when she experienced menarche!Â
When asked the same question our MD expert offered, âUnless having a later period confers some sort of survival benefit, there is no reason why evolution would select for it. Furthermore, Evolution happens on such a long time scale that it would probably be thousands of years before a significant change would happen.â
So the general consensus is that the trend toward menstruating earlier is a result of some bio-evolutionary âadvantage.â What that advantage might be is whatâs most disputed.Â