These findings were statistically massaged. As the authors state: “After adjusting for age, height, weight, ponderosity index, and Tanner stage, testosterone does not exhibit an overall significant racial difference in either sex”.
Height, weight, ponderosity, and Tanner stage correlate with testosterone-induced masculinization. If you correct for these factors, you also ‘correct’ for testosterone. In fact, this is noted in later publications about the Bogalusa Heart Study:
White males are taller and heavier than black males at every Tanner stage (table 1). They have identical or higher mean testosterone levels at 4 of the 5 intervals -- without any statistical adjustment (tables 2 and 3).
The fact that blacks enter puberty earlier is exactly why it would make little sense to compare hormone levels in (pre-)adolescent blacks and whites by age alone and expect meaningful results. I briefly considered pointing this out in my original comment but decided it was obvious.
Note however:
The mean age (Table 1) of black males
compared to white males at Tanner stage II by either staging
method is significantly lower, suggesting that black males
enter puberty before their white counterparts. At Tanner
stage V by either staging method black and white males
again show a significant difference in mean age with blacks
being older, possibly indicating that they finish puberty later
than white males.
White males are younger than black males at the final two Tanner stages. They are barely older at Tanner stage III.
I answered all of your criticisms previously, and at some length, see my blog post at:
http://evoandproud.blogspot.com/2008/03/testosterone-and-human-variation.html
No. You attempted at length to rationalize away with wild speculation and reading incomprehension results that don't support your ideas. You're doing it again here, since you clearly skimmed the Bogalusa study with no aim beyond finding a pretense on which to dismiss it (thus failing to notice the items mentioned above).
The comment to which Peter Frost was replying:
Lindsey is mostly just repeating poorly-supported assertions from Peter Frost.
"Groups with the highest testosterone in the world today are primitive agriculturalists."
Wrong. Testosterone is markedly lower in Sub-Saharan Africans.
"Blacks have much higher testosterone levels than Whites from age 7-24. "
False. See above about blacks in their natural environment. In the U.S., only a tiny study of college students showed a "large" difference and this has never been replicated. Here is much larger study:
A large biracial cross-section of 1038 healthy children aged 6-18 yr with 519 blacks, 519 whites, 678 males, and 360 females was evaluated for Tanner stage and serum levels of androstenedione, dehydroepiandrosterone- sulfate, estradiol, progesterone, and testosterone. The anthropometric values of the blacks and whites were very similar at each Tanner stage with only minor differences in age, height, and weight related to an earlier onset of puberty in blacks. The hormones dehydroepiandrosterone- sulfate, progesterone, and testosterone did not exhibit any racial differences. Estradiol showed a significantly higher level among black males compared to white males (P 5 0.05) whereas androstenedione was significantly higher in both white males (P = 0.0001) and females (P I 0.01) compared with blacks.
[Steroid Hormones during Puberty: Racial (Black-White) Differences in Androstenedione and Estradiol-The Bogalusa Heart Study. J Clin Endocrinol Metab 75: 624-631,1992]
Black men in the U.S. and Africa are consistently found to have higher estrogen levels -- not testosterone levels.
"Black boys’ exposure to high testosterone begins in the womb. Black mothers’ wombs have higher testosterone, and this feeds to the fetus."
Testosterone exposure in utero is not simply a function of the mother's serum T levels.
"Assuming that higher Black testosterone levels are a causative agent in Black crime, aggression and lowered IQ"
Very bad assumptions.
Do you have an explanation? I'm interested in hearing it, no snark intended.
ReplyDeleteWas this a post of his, a comment he left here or an email he sent you?
ReplyDeleteThis may be the crucial black-white difference re T:
ReplyDeleteIt should be noted that the human body’s exposure to testosterone depends not only on blood serum levels but also on how well this hormone interacts with androgen receptors, which seem to be more numerous and more receptive in black subjects (Kittles et al., 2001).
From Frost's post on "Testosterone and Human Variation"
Billare,
ReplyDeleteAs I mentioned in another post: "IQ apparently accounts for more than half the black-white difference in criminality in the US. I suspect variation in genes such as MAOA will eventually be found to account for most of the rest."
I would say it mostly comes to blacks having less self-control.
TGGP,
This was Peter's reply to the one comment of mine that did get posted at guywhite. I refuse to post at guywhite again so I responded here.
togo,
I responded to a similar question here.
As far as I know, it's incorrect that AR are "more numerous" in blacks, and it's not clear to me that would have any relevance even if it were true.
N/s,
ReplyDeleteMy point was that testosterone levels are higher in blacks than in whites during adolescence and early adulthood (up to the early 30s). If you want references, you can check my online article:
Frost, P. (2008). "Sexual selection and human geographic variation", Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society, The Journal of Social, Evolutionary & Cultural Psychology 2 (supp.): 49-65, http://ww.jsecjournal.com/NEEPSfrost.pdf
Nothing you have said invalidates this conclusion. If you break the data down by Tanner stage (as Richards et al.1992 did), you're no longer comparing subjects of the same age. As you point out, black males enter puberty earlier than do white males. So I'm not sure where the disagreement is.
I might add that this transient testosterone advantage is not simply an artefact of early puberty, since it persists well into early adulthood.
Peter Froat,
ReplyDelete"As you point out, black males enter puberty earlier than do white males. So I'm not sure where the disagreement is."
I thought the post was clear. Black males enter puberty earlier but finish puberty later. Matched for age, black males probably have higher testosterone during early adolescence and equal or lower T during middle and later adolescence. The data from this study directly contradict your assertion that:
"this transient testosterone advantage is not simply an artefact of early puberty, since it persists well into early adulthood."
N/a,
ReplyDeleteWell, the data do not "directly" contradict me since the authors did not break their data down by age of subject. You're making an inference, and an incorrect one at that. Yes, African American boys exit pubertal development later than do Euro-American boys, but only about 5 months later:
"These racial/ethnic differences changed somewhat when examining the end of puberty; ie, the attainment of Tanner stage 5. All 3 racial/ethnic groups were within 5 months of each other between their 15th and 16th years for pubic hair growth. However, there was a difference of 1 year between white or Mexican American boys and African American boys in the age at completion of genital development, with the latter being younger."
Herman-Giddens, M.E. (2001). Secondary sexual characteristics in boys. Estimates from the National Health and Nutrition Examination Survey III, 1988-1994, Arch Pediatr Adolesc Med, 155, 1022-1028.
This can hardly account for the persistence of the testosterone advantage among black males into their early 30s. Please read the references below:
Gapstur, S.M., Gann, P.H., Kopp, P., Colangelo, L., Longcope, C., & Liu, K. (2002). Serum androgen concentrations in young men: A longitudinal analysis of associations with age, obesity, and race. The CARDIA male hormone study. Cancer Epidemiology, Biomarkers & Prevention, 11, 1041-1047.
Ross, R.K., Bernstein, L., Lobo, R.A., Shimizu, H., Stanczyk, F.Z., Pike, M.C., & Henderson, B.E. (1992). 5-apha-reductase activity and risk of prostate cancer among Japanese and US white and black males. Lancet, 339, 887-889.
Ross, R., Bernstein, L., Judd, H., Hanisch, R., Pike, M., & Henderson, B. (1986). Serum testosterone levels in healthy young black and white men. Journal of the National Cancer Institute, 76, 45-48.
Winters, S.J., Brufsky, A., Weissfeld, J., Trump, D.L., Dyky, M.A., & Hadeed, V. (2001). Testosterone, sex hormone-binding globulin, and body composition in young adult African American and Caucasian men. Metabolism, 50, 1242-1247.
Peter,
ReplyDeleteLarge, representative samples show small or non-existent differences in circulating testosterone levels between black and white men in the US. None of the references you cite breaks this pattern. Note also that the only study you cite with a large, reasonably representative sample "[does] not support a black-white difference in the age-related declines in serum testosterone".
Gapstur, S.M., Gann, P.H., Kopp, P., Colangelo, L., Longcope, C., & Liu, K. (2002). Serum androgen concentrations in young men: A longitudinal analysis of associations with age, obesity, and race. The CARDIA male hormone study. Cancer Epidemiology, Biomarkers & Prevention, 11, 1041-1047.
"Unadjusted mean total testosterone, SHBG, and free-testosterone concen-
trations were not statistically significantly different between
blacks and whites at any examination (Table 1), except at Year
10, blacks had slightly higher levels (0.0063 ng/ml; P 0.05)
of free testosterone than whites. From the Year 2 to the Year 10
examinations, the concentrations of total and free testosterone
were reduced by a similar magnitude for both black and white
men. Although the reduction in SHBG was greater in black men
compared with white men, this difference was not statistically
significant.
[. . .]
The findings presented here argue against any significant
difference in androgen levels between black and white men
after taking into account BMI and waist circumference. Indeed,
the inclusion of waist circumference as a potential confounding
factor in the associations of race with hormone levels provides
a plausible explanation for differences in the results of this
study with that of previous studies (2–5). One of the previous
studies adjusted only for age (5), whereas others also considered
weight or BMI in their analysis (2–4), but not a measure
of central adiposity. Moreover, our data do not support a
black-white difference in the age-related declines in serum
testosterone."
Ross, R., Bernstein, L., Judd, H., Hanisch, R., Pike, M., & Henderson, B. (1986). Serum testosterone levels in healthy young black and white men. Journal of the National Cancer Institute, 76, 45-48.
This study reports results for a convenience sample of 50 white and 50 black college students. Differences of the magnitude and direction claimed here have never been replicated.
Winters, S.J., Brufsky, A., Weissfeld, J., Trump, D.L., Dyky, M.A., & Hadeed, V. (2001). Testosterone, sex hormone-binding globulin, and body composition in young adult African American and Caucasian men. Metabolism, 50, 1242-1247.
Uses a convenience sample of 23 black and 23 white college students.
"In the current study, the first
to examine the diurnal variation in serum testosterone levels
characteristic of young adult men, the serum levels of SHBG
and total testosterone were higher in African American than in
Caucasian college students living in western Pennsylvania. The
calculated free testosterone level was similar in both groups,
however, implying a similar production rate for testosterone.
Moreover, there was a comparable diurnal variation in total and
free testosterone levels in African American and Caucasian
men with mean levels 25% to 30% lower at 8:00 PM than at 8:00
AM."
(Incidentally: "The size of the testes was slightly smaller (P , .05) in African Americans
than in Caucasians.")
This debate is getting interesting.
ReplyDelete“Large, representative samples show small or non-existent differences in circulating testosterone levels between black and white men in the US”
Those studies use subjects from a wide range of ages. Typically, the mean age is over 30. But it is only over a relatively narrow age span that black men have a testosterone advantage over white men. This transient advantage peaks during adolescence and early adulthood, declines after 24 years of age, and is gone by the early 30s. At older ages, testosterone levels actually seem to be lower in black men than in white men.
It is impossible to break down these “large samples” into year-by-year datasets from adolescence to early adulthood. The datasets would be too small. So the overall “largeness” of the samples is illusory.
I know of only a limited number of studies that have robust samples within the relevant age range. One of these is Gapstur et al (2002). You quote the following passage: “Unadjusted mean total testosterone, SHBG, and free-testosterone concentrations were not statistically significantly different between blacks and whites at any examination.”
This analysis, however, is based only on men 24 years of age and over:
“As mentioned previously, because of the difference in the relationship of age with testosterone concentration between younger and older men, we excluded the 141 black men and 101 white men who were ages 20-23 years from all of the subsequent analyses and included only the 483 black men and 695 white men who were ages 24 years and older.”
Below 24 years of age, the black/white difference is greater, as the authors themselves state in the first sentence of their abstract:
“Serum testosterone concentration appears to be higher in black men than white men, particularly at younger ages”
You also quote this passage from Gapstur et al. (2002):
“The findings presented here argue against any significant difference in androgen levels between black and white men after taking into account BMI and waist circumference.”
First, this analysis applies only to men 24 and over. Second, if you adjust the data for BMI (body mass index) and waist circumference, you’re also adjusting for testosterone. Men who are taller and larger tend to have more testosterone. The authors themselves say as much:
“BMI and waist circumference were inversely associated with total testosterone and SHBG, but only BMI was inversely associated with free testosterone.”
You then discuss the Ross et al. (1986) study, saying “Differences of the magnitude and direction claimed here have never been replicated.” In fact, the differences were replicated by Gapstur et a. (2002) in the 20-23 age group, as well as by Winters et al. (2001).
Finally, you discuss the Winters et al. (2001) study. “the serum levels of SHBG
and total testosterone were higher in African American than in Caucasian college students living in western Pennsylvania. The calculated free testosterone level was similar in both groups, however, implying a similar production rate for testosterone.” Yes, the production rate is probably similar in both groups. The difference seems to be in the retention rate.
Keep in mind that natural selection is operating here on morphological and behavioral traits that are shaped by the amount of testosterone in the bloodstream at any one time. It matters little whether this is done by producing more or retaining more. The result is the same.
Peter,
ReplyDeleteI'll reply eventually in a separate post.
Can you please provide a link to the reply on this page?
ReplyDeleteChris,
ReplyDeleteI don't think I ended up posting a reply. I think my plan was to pull together every related study ever published, looking at the raw data myself wherever possible. But I ended up finding little or nothing in the way of relevant additional studies or raw data.