Precocious Puberty

[beenie]

That's what I was thinking too. It's not just what we eat, it's that we have a basically unlimited access to calories. It would be interesting if we had data from , say, the 1800's when there was a pretty distinct difference between classes who had as much to eat as they wanted, and those who went hungry. No hormones in the chicken then. I wonder if we'd see the rich girls, on average, starting puberty earlier than the poor ones.

I'm not suggesting it's only diet, just one factor of many. Just wanted to clarify...

 

[Falvlun]

I'm not suggesting it's only diet, just one factor of many. Just wanted to clarify...

It likely is a combination effect.

What made me think of it was that I do know that during lean times that women can stop menstruating. Since it's all hormonal based, it would make sense that puberty would also be delayed if the girl wasn't taking in enough calories.

 

[Songbird]

That's what I was thinking too. It's not just what we eat, it's that we have a basically unlimited access to calories. It would be interesting if we had data from , say, the 1800's when there was a pretty distinct difference between classes who had as much to eat as they wanted, and those who went hungry. No hormones in the chicken then. I wonder if we'd see the rich girls, on average, starting puberty earlier than the poor ones.

That would be an interesting insight. One source I just read said, "...the average age of menarche dropped from about 17 to 12.8 during the period 1830-1962. The rate of decline was 4 months per decade."

It seems the Industrial Revolution revolutionized adolescence!

Also from the same site:
"The most widely held belief is that the trend has occurred due to improved nutrition. Children today are bigger and heavier than in the past. Improved nutrition allows for normal growth. Lower classes and rural children have also seen a drop in the age of onset of puberty.

Other causes may include:

Generally improved environmental circumstances
Smaller families
Genetic isolates - a.k.a. natural selection
Gradual change in world temperature
Drop in incidence of disease
Obesity (onset of menarche has a correlation with the body fat percentage)
Sedentary lifestyle"

Average age of menarche in history, at MUM

I want to keep quoting from the article, but it would turn into a long post. After the above list of factors, the author also listed hormones and certain chemicals as possible factors, too.

By far, the biggest association seems to be nutrition. The less food available, the later menarche occurs.

 

[Songbird]

I understood this to come from a natural occurance than when the species is in a harsh environment with a high mortality rate, repoductive ablitites occur earlier in order to ensure survival of the species. I would think that malnutrition would count as hard times. May poor nutrition is a better term though rather then full on malnutrition.

Maybe its a bell curve with early puberty on both ends of the curve. Times are bad; early puberty, times are good; early puberty.[/FONT]

As separate stand-alone factors, stress would cause earlier puberty and poor nutrition delayed puberty, so combined perhaps it's hard to evaluate. From what I've read, even prehistoric peoples in harsh environments had later adolescence than we do today. On the other hand, Eskimo women who lived in 90 degree igloos and led sedentary lifestyles were recorded to have babies starting at 11 years old.

 

[Songbird]

That's what I was thinking too. It's not just what we eat, it's that we have a basically unlimited access to calories. It would be interesting if we had data from , say, the 1800's when there was a pretty distinct difference between classes who had as much to eat as they wanted, and those who went hungry. No hormones in the chicken then. I wonder if we'd see the rich girls, on average, starting puberty earlier than the poor ones.

I just found this journal article with that comparison:

The Timing of Normal Puberty and the Age Limits of Sexual Precocity: Variations around the World, Secular Trends, and Changes after Migration

Scroll down to the bar graphs comparing "well-off" and "underprivileged" averages. In some countries the age difference in puberty is over a year. In India - three years.

 

[PaulTheMaul]

Maybe a sooner onset of puberty is just another step of basic evolution?