The testes are active during gestation, as well as during early infancy. Testosterone elevation during fetal development has been shown to play a role in human neurobehavioral sexual differentiation. The role of early postnatal gonadal activation in human psychosexual development is largely unknown, however. We measured testosterone in 48 full term infants (22 boys, 26 girls) by monthly urinary sampling from day 7 postnatal to age 6 months, and related the area under the curve (AUC) for testosterone during the first 6 months postnatal to subsequent sex-typed behavior, at the age of 14 months, using the Pre-School Activities Inventory (PSAI), and playroom observation of toy choices. In boys, testosterone AUC correlated significantly with PSAI scores (Spearman's rho = 0.54, p = 0.04). In addition, play with a train and with a baby doll showed the anticipated sex differences, and play with the train correlated significantly and positively with testosterone AUC in girls (Spearman's rho = 0.43, p = 0.05), while play with the doll correlated significantly and negatively with testosterone AUC in boys (Spearman's rho = − 0.48, p < 0.03). These results may support a role for testosterone during early infancy in human neurobehavioral sexual differentiation.
Thursday, May 10, 2012
Infant testosterone predicts toddler behavior
A new study from Hormones and Behavior:
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What are the differences between the fetal testosterone that affects the developing brain and the testosterone later produced?
ReplyDeleteWhoa. If this is as predictive as they say, we may have identified something that predicts homosexuality, right?
ReplyDeleteIf these toddlers are followed, it'd be interesting to see if play preferences persist and if they can predict gender atypicality in play.
In today's "Science Daily":
ReplyDelete_____________________________________
"Testosterone-Fueled Infantile Males Might Be a Product of Mom's Behavior"
ScienceDaily (May 10, 2012) — By comparing the testosterone levels of five-month old pairs of twins, both identical and non-identical, University of Montreal researchers were able to establish that testosterone levels in infancy are not inherited genetically but rather determined by environmental factors.
"Testosterone is a key hormone for the development of male reproductive organs, and it is also associated with behavioural traits, such as sexual behaviour and aggression," said lead author Dr. Richard E. Tremblay of the university's Research Unit on Children's Psychosocial Maladjustment. "Our study is the largest to be undertaken with newborns, and our results contrast with the findings gained by scientists working with adolescents and adults, indicating that testosterone levels are inherited."
The findings were presented in an article published in Psychoneuroendocrinology on May 7, 2012.
The researchers took saliva samples from 314 pairs of twins and measured the levels of testosterone. They then compared the similarity in testosterone levels between identical and fraternal twins to determine the contribution of genetic and environmental factors. Results indicated that differences in levels of testosterone were due mainly to environmental factors. "The study was not designed to specifically identify these environmental factors which could include a variety of environmental conditions, such as maternal diet, maternal smoking, breastfeeding and parent-child interactions."
"Because our study suggests that testosterone levels in infants are determined by the circumstances in which the child develops before and after birth, further studies will be needed to find out exactly what these influencing factors are and to what extent they change from birth to puberty," Tremblay said.
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For years they've checked the serum testosterone levels of straight males and gay males and found no differences.
ReplyDeleteHowever, I've never heard of a study in which they've followed testosterone levels of newborns and toddlers and then years later followed up to see if they found a correlation between T. levels in those who turned out to be straight males and those who turned out to be gay males.
Seems they could do this easily enough and then check back with the boys when they are in late teen years, check for sexual attractions.
Say researchers got a larger sample, say a couple hundred male infants and toddlers, and did what they did in this study-- collected urine samples from infancy to early toddlerhood and measured T. levels, then checked back in the boys' teen years when T. levels are virtually the same for gay boys and straight boys.
ReplyDeleteIn a random sample of 200 males, one would expect to find about 4-6 homosexual boys (2-3%). If those boys that had lower T. levels as infants or toddlers are predicted of those 4-6 boys among the 200, they are on to something.
Then, the question would become, what caused the lower T. levels in infancy, early toddlerhood? Well, there certainly are a lot of pathogens that the youngster faces after birth, and not every kid's immune system is likely to behave the same way.
However, I've never heard of a study in which they've followed testosterone levels of newborns and toddlers and then years later followed up to see if they found a correlation between T. levels in those who turned out to be straight males and those who turned out to be gay males.
ReplyDeleteI think the deal here is that 2D:4D results are a good proxy for this, and aren't too impressive.
Also face shape -http://www.cosmosmagazine.com/news/5295/finger-length-predicts-facial-shape-boys
I'm not sure I understand how this story is a story at all. The fact that testosterone at a certain time in utero effects sexual behavior is what I would have called established science.
ReplyDeleteFor example: There is a whole chapter on this called "Hormone Levels During Development" in Simon LeVay's book Gay, Straight, and the Reason Why pp. 129-156 Oxford University Press 2011.
Or for a different perspective there is Brainstorm by Rebecca Jordan-Young pp. 85-87 Harvard University Press 2010.
There are hundreds of other less authoritative references on the web.
This isn't a new idea.
Albertosaurus
I have reconsidered: I first thought that this was pretty big news because it measured post natal testosterone beyond the neonatal stage, but after googling I see this isn't news, unless I am missing something.
ReplyDeleteWhat I've not really found, however, is a study that identifies male neonates and toddlers whose T. levels fall on the lower range when compared to their gender and age group, and then follows them to see if they exhibit gender atypical play and gender atypical interests as they age. Of course, a final step would be to identify if these boys wound up gay.
If Cochran is right-- that it's actually more likely that the pathogen strikes after birth rather than in utero--then studies of neonates and toddlers makes sense.
ReplyDeleteGonads are still providing surges in T. in the neonatal, toddler period.
Whoa. If this is as predictive as they say, we may have identified something that predicts homosexuality, right?
ReplyDeleteHomosexuality has nothing to do with testosterone, or with masculine vs feminine behavior.
There are some male homosexuals who display feminine traits, and female homosexuals who display masculine traits, but they are the exception and not the rule.
"Homosexuality has nothing to do with testosterone, or with masculine vs feminine behavior.
ReplyDeleteThere are some male homosexuals who display feminine traits, and female homosexuals who display masculine traits, but they are the exception and not the rule.'
That is patently untrue.
The most accurate predictor of homosexuality is gender atypicality in play patterns and interests. Check any number of studies by googling. (you can start with Bailey, but there are many others).
You can also google the correlation between gay voice versus straight voice, body language, and mannerisms, and the research showing the correlation between jobs/careers/interests between gay versus straights.
The literature is abundant.
That said, it's true not all gay males are effeminate and not all lesbians are butch, but many lie at the extremes and as far as gay males are concerned, the "average" gay male himself rates himself as less masculine than the average straight, and studies seem to show he's right.
How about commenters use a name of some sort. If everyone posts as Anonymous it puts me in the position of writing something like "Anonymous is more than just wrong he's bloody idiot, whereas Anonymous is a Daniel come to Judgement, informed, articulate and wise".
ReplyDeleteAlbertosaurus
The most accurate predictor of homosexuality is gender atypicality in play patterns and interests. Check any number of studies by googling. (you can start with Bailey, but there are many others).
ReplyDeleteI'm not the anon you're quoting, but it's more a question of how absolute a predictor it is (in terms of explaining all homosexuals), more than whether it is predictive at all, or the most accurate of the ones we have.
Say we had a pop where (for the sake of argument), 1 in 10 were gayers, and of the kids 1 in 30 were effeminate, and they had a probability of 0.6 of becoming gay. That's better than chance, but effeminacy in youth wouldn't be a very good absolute predictor of gayness as adults, no matter how good your other predictors were or weren't.
The most accurate predictor of homosexuality is gender atypicality in play patterns and interests.
ReplyDeleteThat's an utterly meaningless statement. "Most accurate" compared to what?
You might as well say that clouds in the sky are the "most accurate" predictor of rain. Compared to zero clouds in the sky, that's true. The problem is that it's still a piss poor predictor of rain.
it's true not all gay males are effeminate and not all lesbians are butch, but many lie at the extremes
ReplyDeleteWhy not just say "I don't actually know a heck of a lot of homosexual people, other then the ones I've seen on TV"?
An honest admittance of ignorance can be the beginning of knowledge.
"An honest admittance of ignorance can be the beginning of knowledge."
ReplyDeleteI see you don't like to google, just make general claims and then accuse others of doing the same.
Again, look up Bailey, Zucker, Green, Bem, Levay and use their papers to lead you to other research in their biblios.
You might find interesting the brain scan work of Rahman (Karolinksa Brain Institute, Sweden) that shows brain size differences in the amygdala an area regulated the fight/flight response and which found the responses of gay males in the amygdala resemble those of straight women, not straight men, one anatomical, neurological indicator of behavior. That's not going to be the end of the story, for sure.
And, of course, you might also use your eyes and call upon experience from your elementary school days.
However, I suspect you know all about these studies--you simply reject their findings.
It's altogether possible, however, that you really believe a large % of gay men are simply so masculine in their interests and in their mannerisms that you don't think straight men and women don't glean their effeminacy.
Oh, well. Guess you don't have gaydar.
Since you're making the claims, seems like you could at least talk about the size of the damn predictive effect sizes. Should be simple to do if you're as familiar with this literature as you assert.
ReplyDeleteRather than just make vague claims that could just amount to "slightly more predictive than chance, but almost identical to chance".
you might also use your eyes and call upon experience from your elementary school days.
ReplyDeleteMy eyes and experience from my elementary school days suggest that it is very difficult to predict whether a person will grow up to be homosexual on the basis of their childhood personality.
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