Information and Entropy

[noguru]

Now, Johnny, you know the other kids won't want to play with you anymore if you keep doing this.

Yes, I am suprised that Jobeth is unaware of this research which seems to be relevant to the accuracy of her claim.

 

[jobeth]

A study published 3 years ago in the journal Pediatrics found, "Less than 10% of US girls start to menstruate before 11 years, and 90% of all US girls are menstruating by 13.75 years of age, with a median age of 12.43 years. This age at menarche is not significantly different (0.34 years earlier) than that reported for US girls in 1973. Age at menarche for non-Hispanic black girls was significantly earlier than that of white girls at 10%, 25%, and 50% of those who had attained menarche, whereas Mexican American girls were only significantly earlier than the white girls at 25%.

Conclusion. Overall, US girls are not gaining reproductive potential earlier than in the past. The age at menarche of non-Hispanic black girls is significantly earlier than that of non-Hispanic white and Mexican American girls."

http://pediatrics.aappublications.org/cgi/content/abstract/111/1/110

Here is a study from that same publication that affirms my claim:
http://pediatrics.aappublications.o...FIRSTINDEX=0&minscore=5000&resourcetype=HWCIT

Here is another one:
http://pediatrics.aappublications.o...FIRSTINDEX=0&minscore=5000&resourcetype=HWCIT

Noguru:

Yes, I am suprised that Jobeth is unaware of this research which seems to be relevant to the accuracy of her claim.

I had not seen this study before. This study (cited previously) doesn't really pertain as it was a study on Racial Differences and concluded that compared with the recent past (over the last 30+ years) Black American girls reaching menarche earlier than White American girls, has not seen any significant change. Since when is the past thirty years now considered long enough to study evolutionary-type changes?

What I would like to see is a study comparing age of Menarche today with girls of say at least 200+ years ago.

 

[Johnny]

Jobeth,

Here is a study from that same publication that affirms my claim:

A two month change is not really statistically significant and certainly doesn't support the assertion you made. In fact, the study I posted found an even greater change and the authors still deemed it was not "statistically significant".

Here is another one:

This analysis was studying the age of puberty, not the age of menarche. From the paper, "It is important to recognize that there are differences in the pubertal markers "age of onset of secondary sexual characteristics" and "age of menarche." The timing of these events may be regulated differently, making it important to study both. Some data have indicated that the earlier girls begin the onset of secondary sexual characteristics, the longer the time period until menarche is reached."

This study (cited previously) doesn't really pertain as it was a study on Racial Differences and concluded that compared with the recent past (over the last 30+ years) Black American girls reaching menarche earlier than White American girls, has not seen any significant change.

But it does pertain because the relevant data is still there and was analyzed.

Since when is the past thirty years now considered long enough to study evolutionary-type changes?

When I posted that study I was simply responding to your statement, "If the medical textbooks are still saying that average age of menarche is 12.7 years give or take 2 years (11-13), same as they did 50 years ago, and yet most girls in the 21st century experience menarche at age 9 or 10, then the textbooks are clearly wrong and more study is certainly called for by this glaring and embarrassing discrepancy."

It certainly would be interesting to see a study comparing the age of menarche of modern girls to girls 200+ years ago, but that's probably not ever going to be possible.

 

[jobeth]

It certainly would be interesting to see a study comparing the age of menarche of modern girls to girls 200+ years ago, but that's probably not ever going to be possible.

Why wouldn't it be possible?
Since when are Scientists unable to look at bones and teeth and growth and such and determine the sex and the age of a deceased person?

Are you saying it is not physically possible for them to do this for persons dead more than a couple hundred years? Or is it just not politically possible?

 

[chair]

Why wouldn't it be possible?
Since when are Scientists unable to look at bones and teeth and growth and such and determine the sex and the age of a deceased person?

Are you saying it is not physically possible for them to do this for persons dead more than a couple hundred years? Or is it just not politically possible?

age and sex yes, but i don't think they can figure out at what age a dead woman started menstruating.

 

[Johnny]

Why wouldn't it be possible?

Such detailed records in any sufficient volume for a study probably weren't recorded.

Since when are Scientists unable to look at bones and teeth and growth and such and determine the sex and the age of a deceased person?

Sex and age are possible, but I am unaware of any way to tell from a tooth or a bone if the girl has undergone menarche.

Are you saying it is not physically possible for them to do this for persons dead more than a couple hundred years? Or is it just not politically possible?

Physicially.