Lion of the Blogosphere

Why are children entering puberty earlier?

At an NPR article about children entering puberty earlier, while most commenters were blaming stuff like “chemicals” and other unnatural things in the environment, one commenter had an interesting idea:

I wonder, has anyone stopped to think that the time puberty starts may be genetic? Early puberty could easily be linked to having more children. That, coupled with the fact that young people are dying less than they ever have in human history, could point to this just being evolution.

Written by Lion of the Blogosphere

January 3, 2013 at 7:03 AM

Posted in Biology

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25 Responses

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  1. Is this happening within races (ie, are white kids entering puberty significantly earlier than white kids used to, black kids earlier than black kids used to, etc)

    Or is this just a case of measuring different kids because of glory halleluiah changing demographics?

    anonymous

    January 3, 2013 at 1:45 PM

  2. Well, the commenter is correct.

    Imogen

    January 3, 2013 at 2:11 PM

  3. I suspect early puberty is happening even when controlling for child’s race.

    We know that better nutrition and health care is causing Americans to develop in healthier ways than they were a century ago. We know white Americans and Europeans are taller than they were a century and that breast size has increased substantially even after controlling for obesity. Judging by photographs, the faces of white Americans and Europeans appear to be much more symmetrical than 100 years ago, especially for women. Perhaps female beauty is more heavily dependent on mutational load and prenatal as well as early childhood health because facial symmetry indicates developmental stability.

    100 years, there were likely no white women who came close to looking as hot as this chick: Behold the rare 11 out of 10:

    The Undiscovered Jew

    January 3, 2013 at 3:12 PM

    • There is also the fact that regular people are selecting women for pretty faces much more now than in generations past

      anonymous

      January 3, 2013 at 7:08 PM

      • Behold, the woman who looked better at 40 than your 25 y/o.:

        Certainly, all good looking women should age that well. But that Sports Illustrated chick on Youtube is a whole different breed of mink. She’s hot enough that even Richard Dawkins would, in private and strictly off the record, natch, admit she’s robust evidence (if not definitive proof) for the existence of a benevolent God.

        There is also the fact that regular people are selecting women for pretty faces much more now than in generations past

        I’m skeptical. Men have always selected women for beauty but it’s only over the past 80-100 years that there’s suddenly been a substantial improvement in female beauty. A three to four generation time frame is normally too fast for selective pressures to make that much of a difference on a suite of traits.

        It’s more likely female beauty, particularly at the top 9-10 range of the beauty distribution, has shot upwards because of improved health, selective pressures less so. Health would have a more powerful effect on female attractiveness traits such as body and face symmetry, bone structure, breast size, etc than men because female beauty is more important to signalling a women’s reproductive fitness than male beauty is for men. Keep in mind that body and facial symmetry is strongly correlated with all sorts of positive characteristics such as intelligence, height, lifespan, and social status. From a Darwinian perspective, women who possess excellent physical symmetry are signalling to men that she is very capable of passing on these traits to the man’s potential sons.

        I also question Peter Frost and others when they claim faster sexual maturation in boys is due to cads outbreeding dads. If after controlling for race and other important variables boys are healthier than ever before on a range of metrics then it would make biological sense that they sexually mature faster so they have an even longer reproductive lifespan to pass on their healthier genes.

        The Undiscovered Jew

        January 4, 2013 at 12:34 PM

    • If she’d been born in 1890 instead of 1990,she’d have probably had at least one kid by age 25. She would still look hot, but not *that* hot, because having kids changes the body, even for healthy women.

      Anthony

      January 10, 2013 at 12:15 PM

  4. Lion, did you see this graph from Jayman? He found using the GSS that intelligent conservatives have above replacement if their Wordsums are 7-8. Also, the most intelligent liberals have fertility below 1 while the dumbest liberals have the most.

    https://jaymans.wordpress.com/2012/06/01/liberalism-hbd-population-and-solutions-for-the-future/#values

    http://www.parapundit.com/archives/008848.html

    The Undiscovered Jew

    January 3, 2013 at 3:17 PM

    • That’s not the complete story.

      Wordsum has no correlation with with number of children if a measure of religiosity is included in the same regression analysis.

      It’s only because intelligence is negatively correlated with religiosity that there appears to be a negative correlation between intelligence and number of children.

      The Lion

      January 3, 2013 at 3:45 PM

    • “Lion, did you see this graph from Jayman?”

      And this
      http://jaymans.wordpress.com/2012/12/28/its-not-the-cads-its-the-tramps/

      Anon

      January 3, 2013 at 7:35 PM

  6. Because they’re fatter, and fatter kids enter puberty earlier. To its credit, the NPR acknowledged this in the article. NPR commenters are a different matter.

    J1

    January 3, 2013 at 3:51 PM

  7. See Dick & Jane
    See Dick & Jane watch
    President Bill’s
    Oval office Beejers!
    Go Bill, Go!
    See America applaud!
    Applaud, Americans, Applaud!

    See future Gen Useless
    Copy Pres. Bill
    Hey, it’s OK
    See Dick Jane

    Firepower

    January 3, 2013 at 7:15 PM

  8. My son didn’t enter puberty till 14. We have slow growth and extreme longevity among males in our family. He wants to live to 103 so he can live in three centuries: 20th, 21st and 22nd.

    not too late

    January 3, 2013 at 7:33 PM

  9. Dear God what BS. Ge of puberty is so malleable how could anyone say.

    Nicolai Yezhov

    January 3, 2013 at 9:03 PM

  10. The obvious question to ask is whether children are entering puberty earlier than their parents did. I imagine that the NLSY might have this data.

    Brandon

    January 3, 2013 at 9:34 PM

  11. Girls enter puberty sooner if they are living with an unrelated male– so either stepfather or mother’s boyfriend. Given the increase of divorce and out of wedlock births, this is bound to be a factor.

    islandmommy

    January 3, 2013 at 10:21 PM

    • I suppose it’s possible that living with an unrelated man could somehow induce early puberty, but I think it’s more likely that girls who enter puberty sooner are more likely to have children out of wedlock, and pass that tendency towards early puberty on to their daughters.

      Brandon

      January 3, 2013 at 11:02 PM

    • “Girls enter puberty sooner if they are living with an unrelated male– so either stepfather or mother’s boyfriend.”

      That’s not causal. Girls who live with an unrelated male are more likely to have a less-“committal” mother, hence, more likely to be fast-reproducers themselves.

      JayMan

      January 4, 2013 at 10:28 PM

      • Even if this is the case, which is unlikely as unwed motherhood is rapidly becoming the norm in many segments of society, it is more likely than not due to pheromones from the unrelated male.

        islandmommy

        January 9, 2013 at 2:10 PM

      • “Even if this is the case, which is unlikely as unwed motherhood is rapidly becoming the norm in many segments of societyit is more likely than not due to pheromones from the unrelated male.”

        Precisely how are you coming to this (quite wrong) conclusion?

        JayMan

        January 9, 2013 at 3:45 PM

  12. I can think of several reasons for the fall in the age of puberty:

    1) Human beings have been getting fatter. Fat tends to affect female hormones and lowers the age of first menstruation.

    2) Childhood diseases have been disappearing. I have read of a theory that a disease burden can cause slower growth and later maturation.

    3) The hormone melatonin is produced during the night and the level of it falls just before puberty. If melatonin can delay puberty and if staying up in the evening under artificial light interferes with melatonin we can expect earlier puberty.

    4) Alien Space Bats have been aiming sex rays at the Earth…

    Joseph Hertzlinger

    January 4, 2013 at 1:19 PM

  13. […] lot has been made of Kevin Drum’s article on lead exposure and crime.  Much has also been made of research showing that boys and girls are entering puberty at earlier […]

    Early onset puberty and lead exposure « Gucci Little Piggy

    January 7, 2013 at 1:00 PM

  14. Is puberty really starting earlier? This study (pdf) says that a) it’s *hard* to figure out age of puberty from older data, b) while age of puberty has gone down, it’s not by a whole lot, and it’s not monotonically declining since 1900, c) higher BMI *is* a significant factor, which lowers the age of puberty for girls, but may raise it for boys, and d) the timing of different signifiers of puberty is changing – age at menarche is changing differently from age of certain hormone levels.

    Anthony

    January 10, 2013 at 12:27 PM


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