What exactly starts puberty

[bfldworker]

I have been wondering what exactly triggers puberty. Is it weight, diet, environmental or something entirely different.

Why am I wondering this?

I started puberty at 11, maybe earlier. But I was 11 when I noticed pubic hair. My brother who is a year older didn't start until he was 13. My sister who is a year younger started at 7(or so I have overheard my parents talking). I have a friend who is my age and just started growing pubes and I have read stories about people not starting until 16 and some who start at 5 or 6.


I have read (and i wm quoting) "that two genes present at birth, known as GPR54 and KiSS1, are responsible for the onset of puberty.

The GPR54 lies dormant for many years until it's suddenly activated by special chemicals called kisspeptins that are produced by the KiSS1 gene.

The process of puberty starts when kisspeptins turn on the GPR54 gene, sending signals to your brain and triggering a chain reaction in your body."

So I am wondering what factors have to take place for the Kiss1 gene to start releasing kisspeptins.

[tyler1904]

Nothing starts it is just when your body is ready to sexual mature...because the point of puberty is to get your body ready to reproduce

[Poontang King117]

The Pituitary gland in your brain triggers hormones to be produced that are responsible for sexual and physical development.

[Harrier]

bfldworker tbh it sounds like you know more about puberty than I bet most or all people here do. I have nothing. But I learned stuff from your post.

[ska8er]

The Pituitary gland in your brain triggers hormones to be produced that are responsible for sexual and physical development.


This dude has it right.

[hairy balls]

yes man we are all different The Pituitary gland in your brain triggers hormones to be produced that are responsible for sexual and physical development

[Hermes]

I know nothing of the two genes mentioned. I do know the sequence of hormonal events which is as follows:

1. The hypothalamus, part of the brain, release a hormone called GnRH.
2. GnRH stimulates the pituitary gland, located near the hypothalamus, to produce two further hormones FSH and LH. These are named after the functions they have in the female - FSH = Folicle Stimulating Hormone, where follicle refers to follicles that will release an egg and LH = luteinizing hormone, which is the hormone that triggers ovulation.
3. FSH stimulates the testicles to produce sperm while LH stimulates the testicles to produce testosterone.
4. Testosterone is responsible for causing all the other changes of puberty.

There is some interesting reading on the Wikipedia article on GnRh which mentions KISSPEPTIN.

As to what determines the timing, i.e. why does the hypothalamus start producing GnRH when it does, it seems likely there is a genetic component and an environmental component.

The genetic component is suggested by the fact that different people who have a very similar environment can start puberty at different times and there seems to be some correlation from parents to children, i.e. children born to parents who started puberty earlier than their peers are more likely to do the same and the same for later puberty.

The environmental component is suggested by the fact people are entering puberty at a younger age than previous generations. There is no reason to suppose there has been a shift in genes across a large population that would have caused this so the effect must be environmental and it has been proposed that nutrition is part of the key. In particular it has been proposed that the body has a threshold for the minimum amount of energy stored (as fat) to begin puberty and this avoids starting what is an energy intensive process where there would be too little energy to finish it. As to what the mechanism behind that would be I would guess that there is some interaction between the hormones concerned with energy regulation and the hypothalamus.

Should you be able to find any more detail on this it would be interesting.

[Bluebyrd]

I don't know the whole science jazz of it but it's hormones and only certain parts of puberty are environmental.

[bfldworker]

bfldworker tbh it sounds like you know more about puberty than I bet most or all people here do. I have nothing. But I learned stuff from your post.


I read a lot. And if it is a mystery I like to get to the bottom of it. I have always been like that. A mystery begs to be figured out. But this is a mystery I can't get to the bottom of.

[bfldworker]

I know nothing of the two genes mentioned. I do know the sequence of hormonal events which is as follows:

1. The hypothalamus, part of the brain, release a hormone called GnRH.
2. GnRH stimulates the pituitary gland, located near the hypothalamus, to produce two further hormones FSH and LH. These are named after the functions they have in the female - FSH = Folicle Stimulating Hormone, where follicle refers to follicles that will release an egg and LH = luteinizing hormone, which is the hormone that triggers ovulation.
3. FSH stimulates the testicles to produce sperm while LH stimulates the testicles to produce testosterone.
4. Testosterone is responsible for causing all the other changes of puberty.

There is some interesting reading on the Wikipedia article on GnRh which mentions KISSPEPTIN.

As to what determines the timing, i.e. why does the hypothalamus start producing GnRH when it does, it seems likely there is a genetic component and an environmental component.

The genetic component is suggested by the fact that different people who have a very similar environment can start puberty at different times and there seems to be some correlation from parents to children, i.e. children born to parents who started puberty earlier than their peers are more likely to do the same and the same for later puberty.

The environmental component is suggested by the fact people are entering puberty at a younger age than previous generations. There is no reason to suppose there has been a shift in genes across a large population that would have caused this so the effect must be environmental and it has been proposed that nutrition is part of the key. In particular it has been proposed that the body has a threshold for the minimum amount of energy stored (as fat) to begin puberty and this avoids starting what is an energy intensive process where there would be too little energy to finish it. As to what the mechanism behind that would be I would guess that there is some interaction between the hormones concerned with energy regulation and the hypothalamus.

Should you be able to find any more detail on this it would be interesting.

From everything I have read there is no universal consensus. Some think it is environmental, some think it is genetic, some think it may be dietary and other don't know.

I know everyone is different and I know everyone matures at a different rate. But there are several billion people walking around this planet and usually with numbers that high something usually sticks out as to what causes something to happen. You see it happen with other animals be it if they are in a controlled environment or out in the wild.

I understand why some people are hairy or smooth, straight or gay, tall or short, etc, etc. But this one is doing me batty.

Oh well the hunt continues.

[Hermes]

From everything I have read there is no universal consensus. Some think it is environmental, some think it is genetic, some think it may be dietary and other don't know.

My personal view is that genetics are not responsible for people of the current generation starting puberty at a younger age than their parents or grandparents did any more than they are responsible for each generation being slightly taller than the previous one.

Genetic change happens because genes mutate which is pretty much a random event meaning one individual will have the changed gene initially. If the change confers some advantage to them the characteristic can spread because that individual will have more offspring either because of a long life or being more desirable to the opposite sex. Gradually the characteristic can spread through the population but it would take many generations for the new characteristic to become widespread.

Given the time over which the average age of puberty has been changing there is insufficient time for this process to have got very far so this won't be where the change, either in height or in puberty age, is coming from.

When it comes to people of the same generation starting puberty at different ages then clearly genetic could be a factor, though maybe not the only one. I do have an anecdote but note, obviously, that this is not a proper study. A friend of mine was a little on the late side starting puberty whereas I was a little early. He was slimmer than I was, though I wasn't fat, and his father commented that he seemed to be able to eat like a horse and not get fat. Now, looking at the Wikipedia article on Kisspeptin it seems the link with nutrition and energy balance is leptin, which is produced by fat hence the theory that with more fat, and therefore more leptin, there would be more kisspeptin and hence the hypothalamus would start producing gnRH sooner. So, it could be that my friend is genetically different in the way his energy balance system works which means with similar food intake he has less body fat, less leptin, and so on. So, a genetic influence could be indirect.

Oh well the hunt continues.

I think when we first start learning we quickly get the idea that if we don't know the answer yet we just haven't found the right person to ask because all things are known. We start with our parents and then later our teacher and even our friends as well as what we can read in books. As time goes by we may get the notion that there are limits to human understanding though academia currently holds that up to masters degree level it is mostly a case of mastering the existing knowledge and only for a doctorate would one need to do original research. If you pick a narrow subject, though, you may reach the limits of current knowledge much sooner. I am not saying you have reached that point yet but when you speak of scientists disagreeing and there being no consensus that is a sign you are getting close. For all that, good luck.