Boys Now Enter Puberty Younger, Study Suggests, but It’s Unclear Why

[alp227]

Source: NYT

A large study released by the American Academy of Pediatrics suggests that boys are entering puberty earlier now than several decades ago — or at least earlier than the time frame doctors have historically used as a benchmark.

The study, widely considered the most reliable attempt to measure puberty in American boys, estimates that boys are showing signs of puberty six months to two years earlier than was reported in previous research, which historically taught that 11 ½ was the general age puberty began in boys. But experts cautioned that because previous studies were smaller or used different approaches, it is difficult to say how much earlier boys might be developing.

The study echoes research on girls, which has now established a scientific consensus that they are showing breast development earlier than in the past.

The study, which was to be announced at the Academy of Pediatrics national conference on Saturday and published online in the journal Pediatrics, did not try to determine what might be causing earlier puberty, although it mentioned changes in diet, less physical activity and other environmental factors as possibilities. Experts said that without further research, implications for boys are unclear.

Read more: http://www.nytimes.com/2012/10/20/health/puberty-starting-earlier-in-boys-new-study-suggests.html?pagewanted=all

[BVictor1]

1. Genetically engineered food...

chemicals and the antibiotics that are cattle are fed in feed.

Monsanto...

[Odin2005]

24. I hear GMOs make your dick rot off and turn you into a zombie vampire!

[4th law of robotics]

48. Er. No

It's not that.

[Berlum]

65. Yes it is

[4th law of robotics]

66. There has been not study linking

GMOs to boys going through puberty earlier.

[Berlum]

67. You can "believe" that hormones have no impact on puberty

But your "scientific" faith will probably cause pimples

[4th law of robotics]

68. "You can "believe" that hormones have no impact on puberty"

You can believe I said things that I in fact never said.

But your faith in strawmen will only cause you personal embarrassment.

/Besides it's magnets. Or cell-phone radiation. Or chakras being misaligned. Or taking crystals out of public schools. Everyone knows this.

[Megahurtz]

86. GMO's AND

numerous chemicals in the food, water supply, and the air we breath.

[NickB79]

2. I blame Kim Kardashian. NT

[truthisfreedom]

3. Because girls enter younger. I was a boy once... I followed the girls anywhere.

Including into puberty.

[Spitfire of ATJ]

4. "I followed the girls anywhere. Including into puberty."

That could get you slapped.

[greymattermom]

5. endocrine disruptors

from plastics. Our environment is soaked in chemicals, and kids are consuming lots of them from plastic containers.

[Carolina]

9. I heartily agree

think of all the cheap plastic stuff -- toys, food containers, furnishings... We really are awash in it and kids even more so.

I recently remodeled a bathroom and I didn't scrimp on cost because at my age, this is it -- the last remodel I'll likely ever do and I wanted it just right as well as suitable for me when I get (God willing) really old. Anyway, it truly amazed me how bathroom fixtures I was accustomed to being metal are now plastic made to look like chrome: tub spouts, shower heads... each day, with each bath or shower, water comes through all this plastic, too.

Add all this plastic to industrial food production and other environmental changes and what do you have?!

Unforeseen/untold effects on kids growth and development...

[LeftyMom]

6. ^Everybody's an expert.

We can shut down all the PhD programs, DU is on it.

[greymattermom]

34. I'm a PhD

doing neurotoxicology research on BPA in plastics and the link to endocrine disruption and chronic migraine.

[JimDandy]

36. LOL Indeed, 'DU is on it'! n/t

[BuddhaGirl]

37. SNAP!!

[LeftyMom]

39. Goodness, you and your equally esteemed colleagues all on one thread?

The internet is a thing of wonder.

[grantcart]

43. with any link that is remotely close to the subject to a peer review article this reply will

automatically be qualified for comeback of the year.

[SomeGuyInEagan]

72. As one who gets migraines ...

(but NOTHING like what some I know deal with) thank you for your research.

[Doug.Goodall]

7. Violent video games are a contributing factor

We are teaching our kids to shoot guns and kill as soon as they can pick up the controller to the X-Box.

[Ian David]

14. Oh, and the robots. Why do the scientists even make them? n/t

[snooper2]

28. My two year old splats attacking zombies on my wife's nook

re-reading that, I guess if you didn't know what a nook was that could sound bad

[Socal31]

81. I doubt it.

The human species is not too far removed from when young males are trained to be actual warriors. I doubt simulated violence which most people have the ability to separate from the real world, is causing this.

[Bohunk68]

8. Very interesting.

Wouldn't surprise me in the least. After all, if females are developing earlier, why shouldn't males? Or maybe,not. Calls for more study, I would think. It would be easy to jump to a lot of conclusions and suspect a lot of reasons. I recall that for me, it was almost 14 before I achieved a **ahem** point and thought I was slower than my peers. That could've been because of a poor diet and the fact that I was also small for my age and didn't really start growing taller and heavier until I had entered the Navy at 17. So, are the young males today maturing more quickly? By casual observation, that may very well be so, but I have no proof.

[Igel]

29. Default hypothesis.

If you assume that what triggers males and females to enter puberty is the same, then your default hypothesis is okay. Perhaps nutrition. Activity. More artificial lighting. Whatever.

But if you assume that it's things like endocrine mimics that are triggering earlier puberty in girls, then the default hypothesis has to be different. Most endocrine mimics mimic female hormones. Unless there's a surge in female hormones that triggers puberty in males--and I don't "do" biology much, so that may be the case--then endocrine mimics don't justify this hypothesis.

[Liberalagogo]

10. I blame

Obama.

[ZombieHorde]

21. Funny. nt

[McDiggy]

11. Science sort of has an explaination...

Young girls showing breast development earlier makes sense because fat cells excrete estrogen. Highest obesity rate in history of civilization = more estrogen = earlier puberty than in the past.

Not sure why boys are starting to show this, too. But I'd imagine there is an explanation that is pretty simple, like obesity causing it in girls.

[sybylla]

13. Fat cells store estrogen, just like they store energy. Neither is used until the fat is burned.

If this has anything to do with obesity, it's not because fat cells store estrogen.

OTOH, I have nieces, none of whom were fat (the opposite in fact) who went into puberty at 10 and 11.

[Igel]

30. Not just store.

Produce. Fat cells do a bunch of things. For example, they process thyroid hormone precursors into thyroid hormone.

They also actually produce estrogen, IIRC, or convert estrogen precursors into estrogen (which amounts to the same thing by a slightly different mechanism).

And, just as with twin studies, there are probably differences in ethnicities, with the usual statistical caveats. Said within any claim as to why--whether it's correlation based on another factor like diet, vitamin D levels, or toxin exposure or context-free differences in puberty onset.

[Trillo]

31. "obesity"?

Among the many other alleged causes, so popular to cite, too many big gulps, too much sedentary activity like sitting in front of computer/video whatever, it's amazing to me few ever seem to mention the weight gain that occurs from increased long-term output of the body's own glucocorticoids, the body's chemical response to allergy exposure.

So, the next question could be, why are allergies increasing?

[Rozlee]

45. I was reading that in landscaping, the trend is toward

planting only certain male trees, bushes and other decorative plants that only contain pollen to keep cleanup easier, i.e., no fruit, berries, seed pods, etc. that have to be swept or picked up by maintenance workers. I forget what the term is for pollen-only male plants. But, it's blamed for a great deal more allergies in people who have to shop, attend classes, work or do business in areas that have this type of landscaping around them which is quite popular, accounting now for 95% of urban commercial planting. Not to say that it's even the greatest cause. With all the unnatural preservatives we fill our bodies with, the poor quality of air we breath, the way our food is tampered with, I'm sure we can find cause for not only allergies, but also many auto-immune diseases in today's environment.

[2pooped2pop]

12. It's the hormones they pump into the meat.

I've been saying this for a couple of years now. The inclination to get the biggest profit from everything is killing us.

[Doremus]

15. +1

[formercia]

35. BGH

My concern is the Cancer factor down the line.

Fast Food Corporations buy meat from who knows where, places where these class of chemicals perhaps not or poorly regulated.

[sarcasmo]

41. In the milk too, make sure the milk you buy says hormone free.

[4th law of robotics]

49. Hormones are very specific

if they don't match exactly they don't work.

So even if you were absorbing those proteins intact (you aren't) they wouldn't work in humans as they are specific to cattle.

[justiceischeap]

16. Animal growth hormones, obesity, plastics, chemical

That is what is speculated to have effected young girls hitting puberty younger. According to the below article, in the 1800's when young women didn't hit puberty until 17 or 18, it was because of malnutrition.


http://www.huffingtonpost.com/christina-pirello/is-the-early-onset-of-pub_b_677424.html

[Danmel]

17. bpa, phthalates and other endocrine disruptors

Are a major factor. BPA is ubiquitous, in can linings, beverage containers and thermal paper receipts. It is a synthetic estrogen. I would not be surprised if it is a major cause-it is detectable in 93% of the population.

[graegoyle]

18. IANAD, but steroid prescriptions...

I have a few nephews and, when they go to the doctor with a cough, they come home with a prescription for steroids.

[Lakerstan]

19. Internet porn. nt

[Enrique]

20. rap music

and being on my lawn.

[ZombieHorde]

22. I blame the Mayans and horny aliens. nt

[Odin2005]

23. I see the usual suspects have popped up blaming this on their pet outrage.

It's GMOs! No, It's violent video games!

[name not needed]

83. Mother Nature's revenge for us bombing the Moon.

It's that simple.

[snooper2]

25. So do we lower the age of consent now?

[tarheelsunc]

26. Can't wait for Rush to blame the feminazis

[KewlKat]

27. How about

these as possible causes?


Soy formula

Pesticides (chlordane, toxaphene, etc.)

Plastics (such as bisphenol and pthalates which leach out of plastic into food)

Effluent from industrial waste (nonyl phenol, dioxin, PCBs)

Hormones given to farm animals that we eat (dexamethasone)

Real estrogen and progesterone that are ingested as birth control pills and then excreted into the toilet, which then end up in our drinking water (water treatment systems clean up bacteria and other contaminants, but not steroids such as estrogen)

[Tree-Hugger]

50. Yes to this

All of the above are major culprits, not just in our children, but in ourselves. Estrogen dominance is a growing problem in young women and men (yes, males have estrogen, just as females have testosterone) and it is a root cause of many ailments and diseases.

The estrogens and progestins in birth control pills are primarily synthetic, though, which is a whole 'nother can of worms.

[DhhD]

32. Could it be toxic effects of estrogen introduced by objects and or foods?

When one end of the estrogen molecule is removed, testosterone is the resulting molecule.

Why is the brain more sensitive to both hormones at this early age? Why is estrogen overriding testosterone as males age? Could it be the feeding of fruits and vegetables instead of Mother's milk during early life? Sugar which is an acid? Nerves/nerve cells are wrapped in fat not carbohydrates. B sheets (brain-blood barrier) are proteins.

Mother's mild is extremely low in estrogen the first 48 days after birth. The menstrual cycle starts up again to mature another egg during the next 28 days.

[xxqqqzme]

42. That is most interesting.

As a breast feeding mother, I did not resume my menstrual cycles for 5 months after my kids were born. That was 35-40 years ago living in what I would have to characterize as segregated environments (on an island then on our farm). Must look into this.

[Tree-Hugger]

51. Onset of post partum menses

...is related to frequency and duration of nursing as well as other factors such as introduction of pacifiers, formula supplementation, etc. Typically, a baby needs to nurse at least every 4 hours on-demand in order for the mother's body to suppress ovulation and then menstruation. My babies slept 6 hours straight beginning their first night on Earth, so my cycles always resumed quickly.

However, poor diet in the mother, heavy soy use and other environmental factors may now play a part in early onset of menstruation post partum.

[hack89]

33. It is nature's revenge on mankind

says this long suffering father of a teenage boy.

[Bohunk68]

38. I recall reading a couple of years ago

in Discover magazine (if I remember correctly) that young males were getting bigger manboobies because of the lavender oil being put in cleaning solutions. The argument was that lavender oil mimicked estrogen and that that was the cause. Maybe a connection?

[sevenseas]

40. Wow!

I hadn't heard that before....and had wondered what is different now than in the past.

I remember sitting on the beach as a child, and the first time I saw man-boobs (on a fat man) how stunned I was to see breasts on a man....now you can even see them poking out through men's T-shirts- all the time, even thinnish men need training bras.

[Tree-Hugger]

52. Debunked

It was hardly a "study." It was something noted in 3 young boys, all by the same doctor. There wasn't a control group or any other formal study protocol. The lavender oil and tea tree oil were "guilty by association" because they were included in a wide range of products used by these boys. There was no look into the other ingredients - many of which are estrogenic - in these products. There was no determination whether the lavender oil or tea tree oils were true essential oils, or synthetic fragrances. The simple fact that these products likely came in plastic containers, which includes PVCs, phthalates and BPA - all endocrine disruptors - in it's composition, was not investigated. Their diet and other environmental factors were not looked at. It's an extremely flawed "study."

Here is one linked outlining the breakdown and some of the flaws of the study:

http://www.safbaby.com/can-lavender-oil-and-tea-tree-oil-really-alter-a-baby-boys-hormones

[Bohunk68]

54. thanks for the link

So many "studies" are reported out and when the debunking happens it gets lost or not reported in the same magazine in which it appeared. Being on dialup doesn't promote a lot of investigation, unfortunately, and time means that by the time you do look it up, the window has closed. Thanks again.

[Tree-Hugger]

59. No problem :-) n/t

[grantcart]

44. Well clearly it has to do with breastfeeding little circumcised boys at the Olive Garden.

[otohara]

46. The Glut of Fragrances in Hundreds of Products

It's so sad when I see every damn starlet and now Brad Pitt promoting perfume the world does not need. Then there's the fragrances in dish soap, laundry soap, lotions, shampoo, on and on....

Sometimes when I buy something from eBay, it takes a few washings to get the stink out.

Make it stop, shit goes into the air, water, land....

[Tree-Hugger]

55. Don't forget the Komen sponsored pink perfume "for the cure."

That's loaded with a bunch of nasties that will harm your health and contribute to your future breast cancer.

[otohara]

56. Did Not Know This

at the mammogram screening center I go to, they ban employees from wearing scented products and ask patients to not wear it also. Of course like most illnesses, women are more apt to suffer from chemical sensitivities. I'm going to write an email to Komen. Thanks

[Tree-Hugger]

58. Oh there's more...

http://butterbeliever.com/2011/10/22/i-will-not-be-pinkwashed-why-i-do-not-support-susan-g-komen-for-the-cure/

[slackmaster]

47. It's obviously the result of soy-based fake meat products being pushed by vegetarianists

Tofurkey kills.

http://www.environmentalhealthnews.org/ehs/news/estrogenic-effects-of-soy

[Tree-Hugger]

53. Soy

Soy is so harmful to our bodies since we consume it in massive quantities and in many forms. The growth of soy is a drain on the environment. It's not an environmentally crop and it makes me want to beat vegans over the head with a pack of hormone-free organic bacon when they get all uppity and holier-than-thou on my when I'm trying to peacefully eat my grassfed moo.

[Tree-Hugger]

57. Unclear Why? Are they serious?

Of course they are serious. Like anything else in this country, the AAP is bought and paid for.

Let's see, our children no longer play outside as they used to. We use more and more chemicals in our homes, on our lawns, in our schools and on our foods than we have at any point in human history. Processed foods are much larger chunk of the American diet than "Real" foods such as quality meats, veggies and fruits. Kids eat foods with ingredients that take a chemistry degree to figure out. Clothing and products put on their skin are doused in dozens of different chemicals, including formaldehyde. No one is looking at what we put in or on our bodies anymore. We blindly assume that something is non-toxic only because we don't die from consuming it or touching it within minutes. There have been drastic changes to our food and our environment over the past century and it's taking people too long to wake up and realize how we are being harmed. Yes, this sounds like tin foil hat talk, but print this out and remember in in 20 years when the AAP comes up with a "groundbreaking" study stating that it turns out that soy, artificial dyes and flavors and other processed foods as well as all the plastics and chemicals in household and body products are to blame for 100s of ailments. Then the public will be in awe of the AAPs genius and all of us crunchy granola tree-huggers will be scratching our heads and wondering why you didn't listen to us decades before.

[happyslug]

60. Could be the product of bad data?? OR the lack of Data????

As one person mentioned above, this was the result of a Doctor's report on three boys. My comment is when does a male hit puberty? How can you tell? When Women hit puberty, it is when they have their first menstrual cycle. It is an easy to determine event, even for a woman who is NOT expecting it. We males do NOT do the same thing. We have out growth spurt, we start to grow hair around our genital areas, a few years later we start to grow hair on our face. None of these are like a woman's menstrual cycle. Yes, one day you and your friends are looking at girls as "yucky" and the next day you and your Friends are looking at their curves and thinking about how to get your hands on them without getting into trouble (Especially with the owner of the curves). The problem is this is over a long period of time, males just do not get erections one day when they see a woman, when previously they did not. Women onset of puberty is similar except for their menstrual cycle. Thus if one uses a Woman's menstrual cycle you have a solid date to date puberty, you do NOT have a similar event among males. Public hair can occur any time during puberty (and this is true of males and females). Facial hair is a late development. The growth spurt occurs in both sexes, but again over a period of a couple of months, not a one time event like a menstrual cycle.

Just a comment, this may be the result of bad data, i.e. people wanting to see males having an earlier puberty for woman have been showed to have one (Due to the onset of the first menstrual cycle coming earlier in their lives) when it is just want people want to see as to any actual decrease in the age of Puberty. More data is needed, but we may NOT have the needed baseline to have such a study (i.e. when does a male enter puberty? When does a male have his growth spurt? when did it start? when did it end? when did he have his first public hair? his first erection due to sexual desire as oppose to the need to go piss? I fear we do NOT have that baseline. A baseline we have had for generations when it comes to a woman;s first menstrual cycle. Doctor's reported it along with other medical findings (i.e. weight, height etc) but Doctors don's ask their patients when they had their first public hair or exam the genitals of their patients to see if the first public hair has appeared. Thus we have no solid baseline for males like a woman's first menstrual cycle thus it may be impossible to determine if males are entering puberty younger then before (or even at the same time or even later). I fear we do NOT know and can NOT know given the lack of data.

[Bohunk68]

61. that is truly an easy one

and I'm surprised you never mentioned the one thing in your post that indicates for sure that a young male is of breeding age. Erections are not it, you can have an erection as an infant. Nope. It's what I and many other males regard as "it". When you ejaculate semen. See, isn't that easy? All the other stuff follows from there. Hair growth, voice change, growth changes.

[happyslug]

62. Production of Semen is not the same as a Menstrual cycle

Men can produce semen for years before they know they can ejaculate. Semen is produced in the male body and then reabsorbed into the male body if it is NOT ejaculated within about three days of production. The male body does this automatically and they is NO outward indication of such production unlike the menstrual cycle of a woman. A man can be able to ejaculate at age 11 or 12 and not know he can. Unlike a woman menstrual cycle which a woman goes through she knows she is going through it (In theory a woman can avoid all and any menstrual cycles by getting pregnant on her first and then again after birth at the time of any first menstrual cycle after giving birth. This is possible but most woman avoid it for reasons I do not think I have to state).

Thus the fact a man can ejaculate is NOT something he can tell by anything his body is doing that is NOT under his control. i.e. it is NOT something that happens on its own (Erections can occur on their own, but not ejaculations in most cases). Thus again, no way to determine, based on the evidence we have collected in the past,about at what age a man could ejaculate. Unlike the menstrual cycle which we have a long history of when it occurs (It is something women tend to report to their health providers). In some culture it is the single most important even in a woman's life, she is viewed as a full grown woman who needs her own house, as oppose to a child who has to live with her mother (i.e. her parents have to set her up in her own home independent of her parents). in other culture that is the age she is to get married (or at least the earliest age when a marriage can be consummated).

Males just do NOT have such a clear date of sexual maturity. Production of semen and being able to ejaculate can occur years before a man does either. Thus is NOT the same as a woman's menstrual cycle when it comes to the age when a person becomes sexually mature. Males just do not have the same overt act that shows they can get a woman pregnant, this may be do to the fact males take years before they produce mostly mature sperm. At age 12, the majority of sperm a male is producing is called "Immature" sperm, sperm incapable of making it into a woman's vagina let alone getting a woman pregnant. By age 16 a man is producing more mature sperm then immature sperm, by age 18 almost all mature sperm. Can a 12 year old male get a woman pregnant? yes, but it is much harder then for an 18 year old male. Thus again, no hard outward sign of the onset of puberty in males.

[Bohunk68]

63. Did you read your last paragraph

before posting? You totally contradict yourself in the second sentence. And I guess you have no idea how sperm gets into a woman's vagina. You really don't know much about male anatomy or sexuality.

[happyslug]

71. We are talking about the onset of Puberty NOT "male anatomy or sexuality".

Yes they are related but are different. What you mention, in most males, we do NOT have a history of keeping records for such records were not kept in the past nor kept today. i.e. in any particular male we can not say for certain when he can produce sperm based on the data kept today and kept in the past.

On the other hand a women's menstrual cycles gives us a firm date, it was hard to miss even in days of witch doctors. It has been recorded for centuries. Thus the onset of a woman's first Menstrual cycle provides us a good base line to determine if puberty has accelerated or declined in women. We have no similar event that has been recorded for centuries for males.

Thus this report may be based on not only bad data, but the lack of data and why I made my comment about this report. It is based on nothing but the report of one doctor. It may be true, it may NOT be true, but given the lack of any reliable the base line of data, meaningless. That is all the point I was trying to make, i.e. there is NO reliable Data on males that comes close to the data we have on woman's first menstrual cycle.

In the reports regarding women entering puberty at younger ages, that is based on woman having their first menstrual cycle at younger ages. As to the other events that occur in women, is is as unreported or under reported as the changes that occur in men with the onset of puberty (For example my sister's comment on a male in her class, when they left for summer vacation she and he was the same height, when they came back to school in the fall, she had to look up at him for he had grown that much that quickly. Such reports are common, but over a many weeks, months or year basis NOT like the a woman's first menstrual cycle which most women know they are having the day it occurs) .

Now women also go through various changes in their bodies during puberty, but like similar changes in males can not be and are not dated as to extra dates and as such NOT cited in the reports in regards to women entering puberty at younger ages. The reason for this is simple, none of the other changes in a woman's body as well documented as woman's first menstrual cycle when it comes to the date it occurs.

A woman's first menstrual cycle is a firm solid date, nothing else like it occurs in males. When you average out women's menstrual cycle you can get a reliable date as to a change in the onset of puberty. Without that baseline of hard data, any observation as to the change of the onset of puberty is based more on people's opinion than on a hard scientifically determined date. That is all the comment I was making, we need hard data to make the observation made in the report and from what I can determine we have none as to males, nothing that comes close to a woman's first menstrual cycle.

[Tree-Hugger]

74. You are incorrect

You are completely incorrect in saying that we only have hard data regarding menstruation and that we don't have enough data regarding males. Maybe you haven't read anything, but the science of puberty in both males and females is very widely studied and there is a plethora of data out there about all of the developmental minutia in both sexes. There is plenty of reliable data on males. Google "Tanner Stages" or "Tanner Scale" for one. There have long been studies, which are always ongoing, regarding the development of males and females during puberty. Just because you personally are unaware of such data does not mean it does not exist.

[happyslug]

77. Lets look at the Tanner Scales

http://en.wikipedia.org/wiki/Tanner_scale

Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty. In HIV treatment, the Tanner scale is used to determine which treatment regimen to follow (adult, adolescent, or pediatric).

Thus what DATE did a person pass from Tanner Stage 1 to Tanner Stage 2? That DATE is unknowable for the Tanner scale is that a SCALE. It is a GUIDELINE as to where a person is on the path of Puberty. The problem is it contains no HARD dates, i.e. like the date of first Menstrual cycle.

The problem is the rest of what is used on the Tanner Stage Scale is more a guideline then a deadline. Menarche (The First Menstrual cycle) is NOT even used in the Scale, for to use it would make the Tanner Scale unworkable. Menarche can occur in Tanner Stage 3 OR Tanner Stage 4. Both stages cover the age when Menarche occurs.

Again the only HARD DATE is the DATE OF Menarche, everything else is on a scale that by definition varies between different people. Maybe the problem is that I am a hard number person, saying that a woman is in Stage 2 Tanner between the ages of 8.9-12.9 years does NOT tell me when Stage 2 starts or ends. Stage three being between ages 9.9-13.9 years does NOT help me when I look for HARD NUMBERS.

The same source does give an AVERAGE age of Menarche 12.7 years, and then a range of between ages 10.8-14.5 years. The 12.7 is a HARD DATE, it is a Number I can look up in other studies and see of it has gone up or down, depending on the average age of the women in those studies.

On the other hand the ages 10.8 to 14.5 are a range, one woman could have her Menarche at 10.8 months and 50 other woman can have their at 14.5 months and ALL of the dates would be in that range. On the other hand I can go to another study saying 50 woman had theirs at 10.8 months and only one at 14.5 and all the Menarche in that study would also be within the RANGE given. Both Studies, when it comes to RANGE, would be the equivalent for that is the nature of a RANGE.

On the other hand, the AVERAGE AGE of Menarche would be VASTLY different in the examples I gave. The First Average would be close to 10.8 months, the later close to 14.5 months. That is significant difference, yet both groups would be within the same RANGE.

Yes, maybe the problem is I am concerned about NUMBERS, Mean also called Average is a solid number that can indicate a change or lack of change. A change in range can also indicate a change, but only if the range has to change to fit the data. The problem is when it comes to data, the need to change the range is harder to justify for you need more then one data point outside the range to change the range. Furthermore, as can be seen in the ages given for Tanner Stage 2 and 3 Ranges can overlap. It is perfectly possible for an average to change drastically, while the Range stays the same.

Thus my comments on Menarche. It is something we have hard data for, women know when they go through it, often to the day. The Tanner Stages are Ranges in which certain things occur.

More on what a RANGE is from a Mathematical point of view:
http://www.mathgoodies.com/lessons/vol8/range.html

A more detail explanation of what a Range is:
http://en.wikipedia.org/wiki/Range_(statistics)

Definition of what a Median is:
http://en.wikipedia.org/wiki/Median

Mean is an Average (as is Median), the difference between Mean and Median is Mean averages out the actual numbers, Median is the point where half the number are above it, and half below. In most cases they are the same, but in certain circumstances will be different:

More on Mean, Median, Mode and Range:
http://www.purplemath.com/modules/meanmode.htm

Median is generally preferred for it gives what is probably the most correct number given a set of data. Mean can be pulled to high or low by a outliers number that it self is to high or two low. This is also true for Median but to a lesser extent (for this reason Median Income in the US as reported by the IRS excludes people making more then one million dollars).

Thus the Tanner Stages use of Ranges instead of Means or Medians shows that the numbers used within each stage can NOT be used to see if the numbers have changed. Thus my use of Menarche, for it is a Mean and as such is a number when it changes indicates a change in the data the numbers being used represent.

When we discuss numbers, it is Mean and Median that means the most, ranges are almost useless (But is a good way to determine if any given number is unreliable for it is outside the range being tested), modes are mentioned but unless it indicates something radically different then both mean and median also useless (Modes can provide evidence that a set of numbers in the pool of numbers are unreliable and should be removed from the data base).

Thus my point, Menarche is the only solid data base line we have for the onset of Puberty. It is NOT a range, or a mode, it is a mean (and sometimes also a Median). As a mean and/or median the change in the "average age" of Menarche means something. I never said it was the beginning or end point of puberty, but that it is a hard number. It is a solid data point.

On the other hand, a change within a range (such as the Tanner Stages) may mean something, or nothing. Ranges are NOT to be used as a substitute for Means or Medians. So what if certain things occur during certain Tanner Stages, The Ranges are so wide unless we see a SEVERE change in the onset of what is mentioned in the Tanner stages (i.e. forcing a change in the Range of Ages being used) it can NOT be used to see if the onset of puberty in either sex is increasing or decreasing.

My favorite comment was the report of Author of the Tanner Scales that the Tanner Stages can NOT be used to see if the person in a pornography video are over 18 or not for the scales are to be used to see where you are in the range of puberty NOT your age. That shows you the purpose of the Tanner Scale, to give people a guideline on what is occurring, not a deadline as to when it will occur (and probably the reason he kept out Menarche from the Tanner Stages, Menarche is a HARD NUMBER that can occur when a woman is in at least two different stages on the Tanner Scale, and the woman can be in BOTH stages when it occurs and neither, thus the author kept it out of his scale for he wanted the scale to reflect overall development NOT one single act in that development).

As I said earlier, maybe the problem is I am use to using HARD DATA, not Guidelines. I have used Guidelines and understand how to use them, but I also know they are ranges not means. They are guidelines not deadlines. A lot of people do NOT understand the difference between Guidelines and Deadlines and what to used them interchangeability. When you can NOT have a deadline, mean or median, then you have to use guidelines and ranges. When the Tanner Scale was formed, it was formed under the concept of Ranges setting up a Guideline. It was NEVER intended to determine age or when one should enter or exit a stage on the Tanner Scale.

This brings me back to my original point, Menarche is the only hard date point we have. It may be a bad data point, but it is the best we have for it is the only one we have. We males have nothing like it, so any comment on puberty in males are questionable NOT because it may or may not be happening, but we may NOT have the data to show that it is or is not. Menarche is the single well known data point we have as to puberty, and the change in the mean of median of Menarche is a hard number we have to deal with.

[Tree-Hugger]

79. Oh my God

Last edited Tue Oct 23, 2012, 10:02 PM - Edit history (1)

Seriously, dude. Calm. The point is that it's a fact that boys are entering into puberty sooner than usual. So are girls. I am so sorry that no one can provide an exact date that one's testicles got bigger. I don't understand your obsession with an exact date. It's been stated time and again that menstruation is not the onset of puberty, either. Yes, many girls have a date that they remember. For what it's worth, the onset of menstruation is not exact either. Many young girls experience a very light or spotty period at first, which may only last a day or so and may actually go unnoticed. Also, their cycles tend to be irregular at first, so the date from the first period to the next can last for many months. As for reporting - many girls do not report their first period due to shame and fear. I know - I've worked with them. They have been raised to be ashamed of their bodies. As such, those numbers are skewed, too. I understand that you want to be able to have exact numbers, dates and such, but you're not going to get that with either gender. Many men CAN say, my voice changed when I was 14. My pubes grew when I was 12. I got bigger balls when I was 13. That's no different than a girl saying, I got my period when I was twelve. In light of this conversation, I asked my husband and a few guy friends. All of them do remember ages when these things happened. I can tell you I got boobs when I was 9 and my period when I was 11. Menarche is NOT the only hard data. Menarche is NOT used in reproductive science, endocrine science or any other science as "the only solid data base we have for the onset of puberty," primarily because we all know that menstruation is NOT the onset of puberty as it happens at the END of puberty. And many women actually do not remember the exact date of their first period. Some do, many do not.

Again, just because you seem to refuse to acknowledge the science behind it, doesn't mean it's non existent. I love your math. I love that you are into the means and medians. That's fabulous. However, you are just plain wrong when you day that menstruation is the only hard data we have. I'm sorry.

And in the interest of this study, it doesn't change anything. Children are still experiencing precocious puberty more often. Also, did you see my other message? Your original message referred to a study done on 3 children. Is this what all the hullabaloo is about? Because that's not the original study that prompted this thread. The study with 3 kids was a debunked issue regarding boys who used lavender products.

Edit: Check my other response to another comment of yours. I provided you with your mean averages.

[wickerwoman]

64. Girls hit puberty before they menstruate.

Many girls have breasts and public hair and have reached their full height sometimes years before they get their first period. Actually, menstruation is usually one of the last things that happens for girls going through puberty.

Puberty is marked by the surge of hormones that drives the development of secondary sex characteristics, not by any one event. The point of the article is that the trend is for these characteristics as a whole to develop earlier and earlier in both boys and girls.

[Tree-Hugger]

69. Exactly

Puberty is not a one day event. Puberty refers to several hormonal and biological changes, including secondary sex characteristics and the eventual capability to reproduce and it typically lasts over a period of years. It's way more than just hair or semen or menstruation. Also, menstruation is definitely not the beginning of puberty in girls. Typically, puberty begins before that as breast tissue changes and the ovaries mature. Girls ovulate before they menstruate, but this is not a defining moment because most young girls don't know the signs of ovulation. Menstruation is the bigger show, obviously.

Wickerwoman is correct - the point is that we are seeing the onset of puberty earlier and earlier in both boys and girls. Girls are developing mature breast tissue earlier, they are getting hair earlier. They are beginning to menstruate earlier. Boys are experiencing secondary sex characteristics earlier as well.

But seriously, we're harming our kids with the increased processed foods, the less time outdoors in real nature, the sedentary lifestyles and the overabundance of chemicals in everyday products.

[happyslug]

70. But the indication used when Puberty "starts" is the first Menstrual cycle

There is to much variation (and delay in reporting) of the other events that occurs when puberty hits, thus when you read about puberty starting earlier in women, it is based on women having their first Menstrual cycle at younger ages then women in the past.

The first Menstrual cycle is the only real firm date we have in either sexes development in Puberty and thus why it is used. Records of such first Menstrual cycle have been kept for centuries so we have a good idea when it should occur. Yes, it is PART of Puberty for woman, adn oftne one of the last thing to occur, but it is the single best date point for determining if the onset of puberty is getting earlier or later. It is something we have firm data on, something the other items you mention we do NOT have any real firm data.

[Tree-Hugger]

73. Again

Puberty begins before menstruation in women. Menstruation is a milestone of puberty, not a summation and it typically is the last major event that happens during puberty.

Again, while the first period is significant in many ways, including culturally, puberty is defined by a series of biological events and bodily changes. Breasts, hair, body odor, acne, enlarged testicles, voice changes, changes in muscle structure, major height growth spurts are all part of puberty. There have been age ranges for both sexes regarding all of these things for the decades that I have been alive. In fact, there something called the Tanner Scale which identifies the typical stages of pubescent development in both sexes. Culturally, the onset of menstruation can seem more significant in some societies, but it's not the end all and be all of puberty discussion, especially when you get into studying the physiology.

They do not only speak about early puberty in regards to menstruation. There is discussion of early breast development and early hair development as well. Abnormally early breast growth in girls has always been used as a diagnostic factor in early puberty (aka precocious puberty if we want to get technical). In boys, precocious puberty is suspected with the abnormally early onset of voice changes, body odor, enlarged testicles, body hair. There are definitely measurable factors for precocious puberty in both sexes. Again, menstruation is not a primary focus.

Here are some links that may help you.

http://www.med.umich.edu/yourchild/topics/puberty.htm
http://www.livescience.com/1824-truth-early-puberty.html
http://en.wikipedia.org/wiki/Precocious_puberty
http://www.endotext.org/pediatrics/pediatrics13/pediatricsframe13.htm

Here is a link to an explanation of the Tanner Scale:
http://en.wikipedia.org/wiki/Tanner_scale

[happyslug]

78. I have yet to see a HARD NUMBER for males in any of these cites

12.8 years as the average age when a woman has her first Menstrual Cycle is a HARD NUMBER. If it changes to 13 or 12.6 that indicates a radical change. Thus my concern for a HARD NUMBER. We have none for males and none for females EXCEPT for

Now, http://www.endotext.org/pediatrics/pediatrics13/pediatricsframe13.htm did give some hard data for women, but not men and then concentrate on menarche more then any other single factor:

In both sexes, the appearance of comedones, acne and seborrhoea of the scalp are due to the increase in adrenal and gonadal steroids. The mean age at onset of pubertal characteristics in young girls has been revised in 1997 in an extensive population of 17,000 girls evaluated in a cross-sectional study (3), and shown to vary with race, ethnicity, geographical location, environmental and nutritional conditions. The study highlighted the secular trend of puberty, showing that in the mid-1990s pubertal development appeared to begin up to one year in advance in white and up to 2 years in African-American girls with respect to previous reports (1, 4). In Tanner's original report (5) white girls had a mean age at onset of breast development and pubic hair of 11.2 and 11.7 yr, respectively. In the more recent studies, breast stage 2 is reported to occur in white girls at 9.96±1.82 yr (mean±SD) with upper and lower limits of 7 and 13 years, and in African-American at 8.87±1.93 yr with limits between 6 and 13 years. Pubic hair would occur at 10.51±1.67 and 8.78±2.00 yr in white and African-American girls, respectively. The age of menarche seems anticipated with respect to the data by Tanner in white British girls (13.5 yr) (5,6) and is reported to occur at 12.88±1.2 yr in white and at 12.16±1.21 yr in African-American girls, and occurs generally at Tanner stage 4. A variety of environmental and genetic factors are involved in the regulation of menarche. Twin analyses indicated that 53-74% of the variation in age of menarche may be attributed to genetic effects (7). Among these, polymorphisms of the estrogen receptor a (7), insulin growth factor I (7a), and CYP17 genes (7b) were suggested as potential genetic determinants of the age of menarche. Obesity and endocrine disrupting chemicals have been debated as environmental factors associated to the secular trend of puberty (7c,d). In summary, white girls would begin puberty by 10 years of age on average, and AfricanAmerican between 8 and 9 years. In boys, the timing of puberty does not seem to have changed, and is considered normal when it occurs after 9 and before 13.5 years of age (2, 7,8).

The authors of that report ran across the same problem I have, no hard data as to males, and female data is tied in with menarche. Again shows the lack of hard data independent of menarche

[Tree-Hugger]

80. Oh, you want decimals?

They exist. I searched for you. You can find many articles. I am copying and pasting some. I do not wish to look at much more because I am starting to feel creepy looking into all my medical sites for "onset of puberty" and other terms related to that.

Here is one with more hard data for you:

http://www.ncbi.nlm.nih.gov/pubmed/15830588


****Assessment of developmental age: cross-sectional analysis of secondary sexual characteristics.
Greil H, Kahl H.
Source

Institute of Biochemistry and Biology, Department of Human Biology, University of Potsdam, Germany. [e-mail]
Abstract

The developmental age of a growing person does not necessarily correspond to his or her chronological age. The two sexes differ considerably in their developmental tempo, and there are tempo differences also within the same sex. Early developers appear older, late developers appear younger than their chronological age might suggest. Based on a sample of 8675 German boys and 8689 girls of the same ethnicity, aged between 8 and 17 years sex differences of height, weight and secondary sexual characteristics are analyzed. Girls on average, develop faster than boys. Their peak of highest increments of height occurs at 10.2 years and is positioned early within the events of sexual maturity. The peak of highest increments of height in boys occurs at age 11.2 on average and is positioned relatively early within the sequences of secondary sexual characteristics. Maturing development starts with breast-stage 2 in girls at age 10.9 and penis-stage as well as scrotum-stage 2 in boys at age 11.1 on average. The development of pubic hair follows and menarche in girls at age 12.7, respectively spermarche in boys at age 13.8, marks the border to theoretical fertility. There are remarkable differences in the tempo of sexual development between the different types of body shape. In girls the pyknomorphic types are the early developers. Breast stage 2 for instance occurs at age 10.1 in the stocky and corpulent pyknomorphic girls and at age 13.0 in the tall and slender leptomorphic girls. This is different in boys. Here are much less differences between the types of body shape, but generally it is the leptomorphic type, at whom the stages of his secondary sexual characteristics are developed a little earlier.****

See? Boys even have their own special science term - spermarche.

Oh heck, here is another study with more numbers for you.

***Onset of the release of spermatozoa (spermarche) in boys in relation to age, testicular growth, pubic hair, and height.
Nielsen CT, Skakkebaek NE, Richardson DW, Darling JA, Hunter WM, Jørgensen M, Nielsen A, Ingerslev O, Keiding N, Müller J.
Abstract

The onset of production of spermatozoa (spermarche) is the basis for achievement of reproductive capacity in men. We collected 24-h urine samples every 3 months in a 7-yr longitudinal study of 40 normal boys initially aged 8.6-11.7 yr. After centrifugation, the urine was analyzed for the presence of spermatozoa by microscopic examination, and spermarche was estimated on the basis of age at first observed spermaturia. The results were corrected for the intermittent occurrence of spermatozoa in the urine after first observed spermaturia and the fact that the urine samples were collected quarterly. In addition, physical examination, including determination of testicular size by orchidometer measurement, pubic hair distribution (Tanner stage), and height, was carried out every 6 months. Spermarche occurred at a median age of 13.4 yr (range, 11.7-15.3 yr), at a time when testicular size was 4.7-19.6 ml (median, 11.5 ml), and pubic hair distribution was 1-5 (median, 2.5). In most boys, spermarche preceded the age of peak height velocity (median, 13.8 yr; range, 12.2-15.2 yr); at the time of spermarche, median peak height growth velocity was 9.9 cm/yr (range, 7.5-13.4 cm/yr), and median height was 160.4 cm (range, 151.7-175.9 cm). We conclude that spermarche is an early pubertal event and that a wide variation in testicular size and secondary sex characteristics is found at that time. In particular, spermarche may occur when little or no pubic hair has developed, and the testes have grown only slightly.***

Note - like menarche, spermarche can occur with variation in secondary sexual characteristics. Girls will also have a variation in breast development and hair growth at the time of menarche, just as boys with have a variation in testicular size and hair growth at spermarche.


There is this Chinese study which uses interviews rather than urinary/semen samples. http://onlinelibrary.wiley.com/doi/10.1002/1520-6300%28200009/10%2912:5%3C577::AID-AJHB1%3E3.0.CO;2-1/abstract

****Onset of the release of spermatozoa (spermarche) in Chinese male youth

Cheng-Ye Ji1,*, Seiji Ohsawa2

Article first published online: 25 JUL 2000 American Journal of Human Biology Volume 12, Issue 5, pages 577–587, September/October 2000

Abstract

Data on the prevalence of the first ejaculating emission for 83,902 Chinese boys 9 through 18 years were collected using interviews. Median spermarcheal ages (MSAs) were calculated by using the status quo data and probit analysis. Subjects consisted of 61,812 Han boys from urban and rural areas in 29 provinces, and 22,090 minority boys from 17 minority ethnic groups. Median spermarcheal ages were 14.24 years for urban Han boys and 14.85 years for rural Han boys, and ranged from 13.46 to 16.32 years for the 17 minority ethnic groups. The differences in MSAs between urban and rural Han boys in each province were significant and the correlation between MSA of urban and rural boys in each province was high (r = 0.83, P < 0.001). For both urban and rural Han boys, there were significant geographic variations. MSAs of boys living in north China were generally higher than those living in the south, while those living in the west were higher than those living in the east. Variation in MSA may be related to ecological conditions in the Chinese Han populations. The different estimates of spermarcheal ages with two approaches, periodical urine sample analysis vs. interview, and their effect on estimating male puberty are discussed. Am. J. Hum. Biol. 12:577–587, 2000. © 2000 Wiley-Liss, Inc.****

This Nigerian study is fabulous because it equates the psychological changes that occur with the onset of spermarche. As you know, much ado is made about menarche in some cultures as there are psychological changes that occur at that time. This study sought out the psychological changes in males at spermarche. This study found the mean age at 14.3, I think.

http://www.springerlink.com/content/g857388384603q73/

This one comparing spermarche with onset of other SSSC:

http://www.nature.com/pr/journal/v19/n6/full/pr19852185a.html

****Abstract

Pediatric Research (1985) 19, 632–632; doi:10.1203/00006450-198506000-00194
174 SPERMARCHE (ONSET OF RELEASE OF SPERMATOZOA) IN RELATION TO SEXUAL DEVELOPMENT

C Thøger Nielsen1, N E Skakkehæk1, P W Richardson1, J A B Darling1, W M Hunter1, M Jølrgensen1, A Nielsen1, O Ingerslev1, N Keiding1 and J Müller1

1University of Copenhagen, Dept. of Peds. Hvidovre Hospital and Statistical Research Unit, Copenhagen, Denmark. MRC, Reproductive Biology Unit, Edinburgh, Scotland.
Top of page
Abstract

A 7-year longitudinal study of 40 normal boys, aged 8.6-11.7 years at entrance. 24-hour urine analysis for spermatozoa and testosterone was performed every three months and physical examinations every six months. The median age at spermarche was 13.4 years (range: 11.7-15.3 years). Considerable variation in secondary sexual characters was found at spermarche. The median testicular volume at spermarche was 11.5 ml (range: 4.7-19.6 ml) and the median pubic hair stage was 2.5 (range: 1-5). A pubic hair stage 1 and a testicular volume of 4.9 ml at spermarche in one boy aged 13.5 years revealed that spermatogenesis occurs in boys who may be judged clinically as preadolescents. The median age at peak velocity of urinary testosterone excretion was 13.9 years (range: 11.6-16.0 years). In most boys spermarche preceded the age at peak velocity of urinary testosterone excretion.

Conclusion: Spermarche occurs early in puberty, when the phenotype is still rather infantile.****

More on the Chinese study in terms of the different ages of spermarche for rural vs urban boys:

http://www.ncbi.nlm.nih.gov/pubmed/21914335

****[Study of geographic distribution and 10 years' change of spermarche in Chinese boys of Han-group aged 11 to 18].
[Article in Chinese]
Song Y, Ma J, Hu PJ, Zhang B.
Source

The Institute of Child and Adolescent Health, Peking University Health Science Center, Beijing 100191, China.
Abstract
OBJECTIVE:

To analyze the geographic distribution and 10 years' change of spermarche in Chinese boys of Hangroup aged 11 - 18.
METHODS:

Calculate the average age of spermarche of Chinese boys who participated in National Physical Fitness and Health Surveillance in 2005 and 1995. The sample size of boys was 69 320 in 2005, 68 992 in 1995 National Physical Fitness and Health Surveillance, respectively. The geographic distribution of Chinese boys were categorized into 6 areas as north, northeast, east, south central, southwest and northwest by administrative divisions.
RESULTS:

The average ages at spermarche were 13.98 and 14.22 years old for urban and rural boys in 2005, respectively. The average ages at spermarche were 13.57 and 13.72 years old for urban and rural boys who living in southwest of China. And the average ages at spermarche were 14.18 and 14.39 years old for urban boys who lived in northwest of China, and rural boys who lived in south central of China, respectively. The average age of spermarche of the top 5 provinces were Chongqing (13.28), Guizhou (13.47), Hainan (13.47), Sichuan (13.56) and Tianjin (13.61); and the last 5 provinces were Hubei (15.30), Qinghai (15.13), Liaoning (14.75), Guangxi (14.68) and Shanghai (14.55). The average ages of spermarche were 14.43 and 14.77 years old for urban and rural boys in 1995, respectively, and thus the ages of spermarche in 2005 were 0.45 and 0.55 years earlier than that of urban and rural boys in 1995.
CONCLUSION:

There was a large variation among different geographic areas. The onset of spermarche was generally earlier in urban than in rural boys, the earliest in southwest of China, and the latest in northwest and south central of China. Significant decline trend of age at spermarche could be found in Chinese boys, especially in rural areas.*****

And, finally, the original study that prompted the original post in this thread:

http://www.doctorslounge.com/index.php/news/pb/32990

****AAP: Secondary Sexual Features Developing Earlier in U.S. Boys
Last Updated: October 22, 2012.



Variation according to race; African-American boys developing earlier than white, Hispanic boys


For U.S. boys, the mean age for development of secondary sexual characteristics is earlier than reported previously, and varies depending on race, according to a study published online Oct. 20 in Pediatrics to coincide with presentation at the annual meeting of the American Academy of Pediatrics, held from Oct. 20 to 23 in New Orleans.

MONDAY, Oct. 22 (HealthDay News) -- For U.S. boys, the mean age for development of secondary sexual characteristics is earlier than reported previously, and varies depending on race, according to a study published online Oct. 20 in Pediatrics to coincide with presentation at the annual meeting of the American Academy of Pediatrics, held from Oct. 20 to 23 in New Orleans.

Marcia E. Herman-Giddens, P.A., M.P.H., Dr.P.H., from the University of North Carolina at Chapel Hill, and colleagues examined data from racially and ethnically diverse U.S. boys to determine the age of onset of secondary sexual characteristics. Tanner stage and testicular volume data for 4,131 boys were collected by 212 practitioners in 144 pediatric offices. The prevalence and mean age of onset of sexual maturity markers were assessed.

The researchers found that, for non-Hispanic white, African-American, and Hispanic boys, the mean ages of onset of Tanner 2 genital development were 10.14, 9.14, and 10.04 years, respectively. For stage 2 pubic hair, the mean ages of onset were 11.47, 10.25, and 11.43, respectively. Testicular volumes of ≥3 mL were achieved at a mean age of 9.95 for whites, 9.71 for African-Americans, and 9.63 for Hispanics, with the corresponding ages of 11.46, 11.75, and 11.29 for ≥4 mL. Compared with white and Hispanic boys, African-American boys showed significantly earlier mean ages for stage 2 to 4 genital development and stage 2 to 4 pubic hair.

"The causes and public health implications of this apparent shift in U.S. boys to a lower age of onset for the development of secondary sexual characteristics in U.S. boys needs further exploration," the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including Novo Nordisk and Abbott, which manufacture growth hormone and testosterone, respectively.*****

[happyslug]

82. Of the reports you cite, only the last one had anything on point

The rest of the Studies indicated a difference between Men living in Rural Areas and Urban Areas and if different regions but no change as to onset date.

The last report DOES have such a report,
Observed mean ages of beginning genital and pubic hair growth and early testicular volumes were 6 months to 2 years earlier than in past studies, depending on the characteristic and race/ethnicity. The causes and public health implications of this apparent shift in US boys to a lower age of onset for the development of secondary sexual characteristics in US boys needs further exploration.

The question then is what was the past studies and are we comparing apples and oranges. Tanner Scale was only first mentioned in 1962 and by the early 1970s became part of the Human Growth Chart.
http://www.utmb.edu/pedi_ed/CORE/AdolescentMedicine/page_03.htm

Thus the Tanner Stages have only been in use since 1962 and widespread use since the early 1970s. While this is a significance amount of time, it does NOT compare to studies using Menarche. The report you cite, you only cited the Abstract and since I am not willing to pay for the actual study, I can NOT see when the previous study was done AND if is used the Tanner scale or some other scale.

Furthermore, the report you mention support other reports I have read, showing a significance increase in the onset of puberty as males moved from Rural to Urban Settings (Urban boys have early onset of Puberty then Rural Boys of the same age). How important is the shift to urban environments is not mentioned but it is clear from the data given in the abstract.

Having made the above observation, it does contain HARD DATA, something the other studies do not when it comes to the any change in Male onset of puberty. The Chinese's study just pointed out the difference in onset of male puberty between various areas of China NOT over any time period. The last study does show a change over a time period, and it seems to be based on some hard line data point.

If the previous studies this study is using as its base point was done after 1970, the Tanner Scale should have been used, but if done before then a different set of observation was used and somehow transformed into a Tanner Scale system. I suspect a 1970 or post 1970 study is the data base line for a generation is a good time measure to compare developmental changes over time.

I have to mention that while most people moved from Rural America to Urban America prior to WWII, African Americans only started to do so in large numbers during and after WWII. This movement peaked in the 1950s and 1960s (Causing the Murder Rates of most American Cities to go above the National Average, prior to the 1960s most murders occurred in the Rural South, causing most American Cities to have lower murder rates then the national average murder rates. The primary reason is AFrican Americans brought with them the culture they grew up in, The Rural South with its high murder rate. Since the 1970s the Murder Rates for African Americans have DROPPED, as African Americans living in Urban Areas adopted Northern Attitudes to violence, this trend continues to this day).

The slow decline in the African American Murder rates shows how slow it takes for people to adopt a new Culture, 50-100 years. This report can be construed that such a slow change can occur in puberty rates due to moving from one area to anther, i.e. from a Rural Areas to an Urban Area.

Several years ago, they was a study done on male sperm counts and how it had declined since the 1960s. The problem was the two studies used, had different data base points. The study done (late 1990s early 2000s) was based on sperm counts done world wide. The study it based point was had used only males living in New York City. Comparing the two studies showed a sharp decline in Sperm counts in males between the 1960s and 2000. This was reported in the papers before critics were finish make comments on the second study. One Critic pointed out it was known that males produce more sperm based on being around more males, thus urban Males will always produce more sperm then a male living in a rural sitting. The first studies had used New York City Residents and thus had high sperm counts due to living in a City, The Second study was based on males from all over the world, from both rural and urban areas and thus would naturally have a lower sperm count.

How this affects the on set of puberty is unknown, but I mention it for it shows the danger of comparing incompatible studies. I would like to see how urban and rural environment affects the onset date of puberty, for it looks like it is a factor. When the male in question moved to an urban area may also be a factor.

Just comments on WHY this change in onset date for Males occurred. THis report seems to overcome my objection to the report used in the start of this thread, i.e the lack of hard data points. On the other hand the abstract is good enough to show that the Study MAY show they did look in urban-rural change AND changes due to changes in area (which seems to be a Factor in the Chinese Report you cite).

Interesting report, have to look to see if I can find more about this report for it seems to answer my concerns for it seems to show solid data of a change onset date for males entering puberty.

Further Reserch.

I did find a cite with a more details on the study, One comment was the earlier study used was an English Study from the 1950s to the 1970s (And given those dates may or may NOT have used the Tanner Scale) . and the folllowing comment:

The meaning of the differences by race/ethnicity in the onset of puberty and in testicular growth "is unclear," according to the authors, "as no existing studies inform differences in mean testicular size at given ages, by race/ethnicity, and sexual maturity stage; or in racial/ethnic differences in the rate of advancement through the Tanner stages over time."

They acknowledged that the study sample may not be representative of boys from the U.S. population and that the age calculations may lack precision because of the inability to collect the day of birth due to privacy considerations.
http://www.medpagetoday.com/pediatrics/generalpediatrics/35453

And that African Americans start puberty earlier then whites or Hispanic may have been a factor, given no Africans-Americans to Hispanics seems to have been used in the earlier studies. The two earlier study indicated that while males have advanced 1.5 years since the British Stidy starting in the 1950s, but only six months from an earalier American Study.

http://www.medpagetoday.com/pediatrics/generalpediatrics/35453

In Report in SLATE on this study the following comment was made:

Only one previous study has documented American boys’ testicular volume using orchidometry , and it was on a smaller scale than the new study, so it’s unclear whether boys are really beginning puberty earlier than they used to—we simply don’t have comparable data from earlier decades.

A note to a 2010 Saudi Arabian Study on Puberty made this comment:

This report of considerably earlier onset of puberty in boys is the subject of ongoing debate internationally. An expert international panel was established to evaluate
data from 1940 to 1994 to determine the evidence of secular changes over time in US children. It was concluded that there were insufficient data to evaluate secular trends in male pubertal development.
21
This debate supports both re-evaluating the reliability of the published data concerning the age of puberty onset in boys and re-studying puberty maturation in boys using a reliable methodology.3,26

puberty Onset Among Boys in Riyadh, saudi ... - Libertas Academica
Aims: The aim of the Riyadh Puberty Study was to provide data on pubertal
development to ... Results: The mean age (standard deviation) at Tanner Stages
2, 3, 4, and 5 for pubic hair .... increase in testicular volume (more than 3 ml), fol- ...
www.la-press.com/redirect_file.php?fileId=2945&filename=2151-CMPed-Puberty-Onset-Among-Boys-in-Riyadh,-Saudi-Arabia.pdf&fileType=pdf

The report went on and found that the average age at the onset of Stage 2 was 11.4 in Saudia Arabia, well within the Margin of Error of earlier English Studies showing ages of onset of 11.6 and a US study of an onset date of 11.5 years (and various other studies done in other countries, all within the Margin of Error of the Sample).

[Tree-Hugger]

84. There's a lot more out there

But I'll leave the searching to you. It's there, though. It's especially good if you have any access to any of the journal sites or university sites that require membership. You should be able to find more there. There have been studies done, but you have to wade through a lot of other stuff to find them.

My overall concern is not exact numbers. We're taking a hit to our health with the Standard American Diet, the lack of outdoor time and the increasing exposure to synthetic chemicals. We're fooling ourselves if we think otherwise. Sadly, it's our children who suffer most.

[happyslug]

85. On those factors I have to agree,

I consider one of the worse thing to happen to education was the replacement of Recess with Gym. With a Recess the kids were sent outdoors not into a gym. They could interact with each other instead of stand around till it was they time to do something in gym.

As to comments on this thread, they wee limited, for we have to be careful when we use studies, make sure they are reliable. That is the reason I made my comment, and subsequent research shows that my concern is NOT with foundation. The author of the report even questioned its findings due to the lack of reliable data and one of the purposes of the study was to establish a base line for later research to use.

Side note: One of the reasons I want to make sure we have reliable data is how data can be misused if we are NOT careful. For example one time I was looking up Silent Spring on the net, and ran across 3 to 4 pages attacking it before I ran across Silent Spring itself and its affect on the environmental movement.

Worse, when if you would read those various attacks on Silent Spring, they tend to cite one Author, who if you look him up actually AGREED with Carson and Silent Spring. His comment was that a 100% ban on DDT removed one of the most effective weapons against Malaria IF USED PROPERLY. A position that even Carson supported.

The problem is the people who wanted to use DDT did not want to be restricted by the restriction the author they were citing insisted on. i.e. no spraying just to spray, limited use around windows to kill mosquito's as they tried to work they way through mosquito netting. No spraying of birds (and the keeping of Chickens close to one's home for Mosquito's prefer Chickens to people). No spraying of fields etc. No spraying of the Chickens etc.

I remember going through pages of attacks on Silent Spring and Malaria and if you ever read Silent Spring Carson NEVER called for a ban on DDT, but restrictions so using it would NOT harm birds. The problem was given a choice, the users of DDT would rather have a ban then limitations thus the ban was imposed.

Even today, if DDT was restricted to use to kill mosquito's in windows and doors, it would reduce Malaria immensely AND do minimal harm to the birds. The problem is farmers want to use it over all their fields to kill every insect, no matter how that affects the birds and other animals. Other want to spray whole cities, lakes, forests etc to get rid of Mosquito's. Such spraying would end up killing all of the birds in the area and the effect on people would be harmful. Thus the need for a ban and why the ban was adopted.

The use of that author's comment to attack silent spring is an example of taking something out of context and then using it for something that the person who made the comment opposed. The right does that all the time and yells when we do it, so lets be careful and make sure we use studies that is supported by solid evidence NOT speculation or desire.

[Tree-Hugger]

76. No

This study was not done on three boys. The study referred to in the OP was large. What you are referring to is a comment I left as a reply to another comment regarding a study involving products containing lavender and tea tree oil. The study referred to in the original post is different.

[Evasporque]

75. no evolutionary advantage to remaining prepubescent

back in the day the advantage is that the longer you remained a child the more likely you were protected by the community...boys that went into puberty sooner died more frequently as the result of assuming an adult role in the community...thus they failed to reproduce...so natural selection dictates that a longer childhood was selected for...

That selection process is probably no longer valid as it once was....so boys can now enter puberty sooner without having a sword tossed into their hands and sent to die....