Re: [evol-psych] Study suggests that tomboys may be born, not made
- From the description it sounds a great deal like the studies carried out
years ago by June Reinisch at the Kinsey Institute. She reported that
girls with higher levels of prenatal exposure to androgens were muchg
more likely to be tomboys than those not so exposed. I have not read the
current study and perhaps it adds something to the earlier research, but
certainly in view of this and other earlier research findings we are not
entitled to the evident surprise this current study evoked. It is
exactly what one would expect from the earlier research and its
implications are the same. Perhaps my problem is that I continue to be
surprised at the scientific communities apparant lack of collective
Incidentally, June Reinisch is also responsible for the following
wonderful quotation, which appears in the Columbia World of Quotations:
"When people say women cant be trusted because they cycle every month,
my response is that men cycle every day, so they should only be allowed
to negotiate peace treaties in the evening."
Ian Pitchford wrote:
> Public release date: 12-Nov-2002
> Contact: Karen Hart K.J.Hart@...
> Center for the Advancement of Health
> Study suggests that tomboys may be born, not made
> Levels of testosterone during pregnancy appear to influence the gender-role
> behavior of preschool girls, according to a new study.
> Researchers measured pregnant women's levels of testosterone, then evaluated
> the behavior of their children at age 3 1/2. The greater the maternal
> testosterone level, the more likely girls were to engage in "masculine-typical"
> gender-role behavior, such as playing with toys typically preferred by boys. No
> correlation was found for boys' behavior, however.
> The researchers based their hypotheses on animal studies that have shown a
> correlation between maternal levels of testosterone and behavior in female
> "Because hormones influence basic processes of brain development, they also
> exert permanent influences on behavior," says lead author Melissa Hines, Ph.D.,
> of City University in London "In both rats and rhesus monkeys, genetic female
> animals treated with testosterone during critical periods of prenatal or early
> postnatal life show increased levels of . male-typical play behavior as
> Hines and her co-authors note that girls with congenital adrenal hyperplasia
> (CAH), a genetic disorder involving prenatal exposure to high levels of male
> hormones, tend to prefer masculine-typical toys and activities.
> The study results appear in the November-December issue of Child Development.
> Participants were part of the Avon Longitudinal Study of Parents and Children,
> a long-term study of biological, environmental and social factors associated
> with pregnancy outcomes and child health. A total of 13,998 pregnant women --
> who represented 90 percent of all pregnancies occurring in the Avon, England,
> area during an 18-month period in the early 1990s -- enrolled in the study.
> Data from 679 offspring of the 14,138 children born during the study were
> The researchers obtained blood samples from the pregnant women during routine
> prenatal medical care; 55 percent of the women had blood taken between weeks 8
> and 24 of the pregnancy; a quarter of the women had the samples taken between
> weeks 5 and 7, and the remainder after week 25. The samples were analyzed for
> levels of testosterone and a hormone that limits the ability of testosterone to
> act, called sex hormone binding globulin.
> Once each child reached age 3 1/2, a primary caregiver completed the Pre-School
> Activities Inventory (PSAI), which assesses the child's engagement in various
> sex-typed behaviors, such as play with certain toys, games and activities.
> Higher scores indicate more masculine-typical behavior. The questionnaire was
> completed again when the child was 3 1/2.
> The authors found a link between testosterone level in mothers and girls'
> scores on the PSAI, with high testosterone levels related to high "masculine"
> scores. No relationship was found between testosterone levels and boys'
> gender-role behavior, however.
> The researchers note that "sex differences in childhood gender-role behavior,
> including toy, playmate and activity preferences, develop as a consequence of
> numerous influences. . For instance, parents, teachers and peers provide more
> positive reinforcement for sex-congruent play than for play that is not
> They therefore identified background variables from the data that may be linked
> to gender-role behavior, such as maternal education, the presence of older
> brothers or sisters in the home, the presence of a male adult living in the
> home, and parental adherence to traditional sex roles.
> "These background variables cannot account for the observed relation between
> testosterone and PSAI scores in pre-school age girls," writes Hines.
> The authors suggest that the effects were not seen in boys because boys
> ordinarily are exposed to higher levels of prenatal testosterone.
> "Compared to girls, boys are more strongly encouraged to behave in sex-typical
> ways and are more strongly discouraged from engaging in cross-gendered
> behavior," they write. "Thus, girls may be more likely than boys to manifest
> hormone-related predispositions to gender-role behaviors more characteristic of
> the other sex, because these predispositions are less likely to be counteracted
> by other influences."
> The study was supported by the Wellcome Trust. The Medical Research Council,
> Department of Health, the Department of the Environment, British Gas and other
> companies also support the Avon Longitudinal Study of Parents and Children. The
> U.S. Public Health Service (HD 24542) also supports Dr. Hines' research.
> FOR MORE INFORMATION
> Health Behavior News Service: (202) 387-2829 or www.hbns.org.
> Interviews: Contact Karen Hart at K.J.Hart@....
> Child Development: Contact Angela Dahm Mackay at (734) 998-7310 or
> News in Brain and Behavioural Sciences - Issue 76 - 9th November, 2002
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/