Re: Geary 3

From: Chatwin Judy (JAChatwin@aol.com)
Date: Mon Feb 16 1998 - 17:38:14 GMT


Sexual selection and sex differences in mathematical abilities
Section 3

3. Evolution of sex differences

>For the present argument, sexual selection is broadly defined to include
>characteristics that directly influence the outcome intramale competition,
>such as
>physical strength, as well as less direct influences on the outcome
>of any such
>competition.

Does this mean that all sex differences can be accounted for by the desire for
males to compete against other males in order to win a mate?

>Trivers (1972) argued that sex differences in the level of parental
>investment in
>offspring "governs the operation of sexual selection" (p. 141),
>and, as such, is
>the ultimate cause of any associated sex differences.
>The higher-investing sex, in contrast, is expected to be much more
>discriminating
>in terms of choosing sexual partners, with discrimination
>focusing on a potential
>partner's physical characteristics or behaviors that
>might benefit future offspring.

Does this not reflect the fact that women are far more limited in the number
of off-spring they can produce and therefore have less room for error?

>First, sex hormones are likely to be an important proximate mechanism for the
>development of any sex differences associated with sexual selection.
>Second, sex differences in social behaviors and cognitive abilities that are
>relatively insensitive to historical and cultural changes also need to be
>considered
>as potentially related to sexual selection.
>Third, it is possible that sex differences in early play patterns influence
>later sex
>differences in cognitive abilities (Serbin & Connor 1979).
>Finally, the associated social and cognitive skills should serve some
>plausible
>function related to reproductive success.

When looking at sex differences in social and cognitive styles, you need to
consider the influence of sex hormones, which behaviours and abilities have
not been affected by history and cultures, how early developmental behaviour
can affect later ability and their relevance to successful reproduction.

>Human males are verbally and physically more aggressive than females across
>cultures (Eibl- Eibesfeldt 1989; Rohner 1976).
>Moreover, Susman et al. (1987) found that during adolescence, adrenal and
>gonadal hormones were related to aggression and delinquency in human males
>but not females.

Does this increased aggression relate to increased competitiveness in the
classroom? If this is the case why does it not affect all academic
achievement rather than emphasize mathematical ability?

>..sex differences in competitive and aggressive behavior are often very large
>under conditions that represent a threat to the male's status, or might
>directly
>influence reproduction, e.g., sexual jealousy (Daly & Wilson 1988;
>Wilson & Daly
>1985).

Beware generalizations, the author seems to be forgetting the male individuals
who do not display these characteristics. If aggression and competitiveness
are such dominant features when why hasn't natural selection led to these
characteristics being displayed in all males?

>During the preschool years and into adulthood, girls' social styles reflect,
>relative
>to boys' styles, a greater concern for egalitarian relationships,
>more cooperation,
>and a greater concern for the feelings of other group
>members (usually other
>girls; Buhrmester & Furman 1987; Maccoby 1988; 1990).

>..males appear to be relatively more object oriented, and females more people
>oriented (McGuinness 1993; Thorndike 1911).
>This is not to say that this pattern necessarily supports a proximate
>mechanism
>associated with sexual selection, but rather suggests that parental
>socialization is
>not likely to be the sole cause of the sex difference in
>object versus people
>preferences.

This would seem to be an important factor in explaining the differences in
mathematical abilities.

>Nevertheless, it is more likely that the object preferences of boys reflect a
>bias
>toward learning about the physical, as opposed to the social,
>environment.

I agree, but remember there are exceptions.

>..it has been frequently argued that the male advantage in certain areas of
>mathematics (e.g., problem solving) is related to a male advantage in spatial
>abilities (e.g., Benbow 1988; McGee 1979).

>..in a meta-analysis of sex differences on the Mental Rotation Test (MRT;
>Vandenberg & Kuse 1978), a measure of the ability to mentally rotate 3-
>dimensional geometric figures, Masters and Sanders found a substantial male
>advantage (3/4 to 1 1/4 standard deviations) in 14 of the 14 studies
>assessed.

Need to consider the cognitive abilities used for this test and relate them to
other mathematical abilities.

>Furthermore, "there is now substantial evidence that cognitive patterns may
>vary
>with phases of the menstrual cycle in normally cycling women and with
>seasonal
>variations in androgens in men" (Kimura & Hampson 1994; p. 57).

It seems that hormones cannot be ignored when considering any sort of sex
differences in cognitive abilities.

>The point is---if males with superior spatial abilities (which facilitate
>hunting and,
>for example, group migration or warfare) had even a slight
>reproductive
>advantage over their low-ability peers, then a sex difference,
>favoring males, in
>certain spatial abilities (e.g., those involving the
>processing of 3- dimensional
>information) would have emerged over the course
>of human evolution.

But what about those males who do not display such superior ability - why are
they here at all?

>For complex spatial measures, the male advantage is found across historical
>periods and cultures, is influenced by prenatal exposure to sex hormones, and
>fluctuates with circulating levels of sex hormones.

>The proximate mechanisms governing the emergence of these sex differences
>include sex hormones and a biological bias in the spatial-related activities
>of boys
>and girls, a bias that is also likely to be influenced by
>sociocultural factors.

As usual - a bit of both!

>..the position that sexual selection might be related to the tendency of
>males to
>show more variability in some cognitive domains than females is
>relevant to the
>issue of sex differences in mathematics (Benbow 1988;
>Feingold 1992;
>Thorndike 1911).

>Greater variability in reproductive strategies would presumably result in
>greater
>variability in any associated social or cognitive domains.
 
>..there are more males than females at the high and low ends of many ability
>distributions..

It is unclear just how great this variability is and therefore how relevant it
is. It is possibly that social factors could explain it.

>.. not only are males more variable in many cognitive abilities, they are
>also at
>much greater risk than females for an array of neurodevelopmental and
>other
>physiological disorders (e.g., Gualtieri & Hicks 1985; Stillion 1985).
>Sex hormones have been implicated as one source of these physiological sex
>differences..
>Such deleterious effects of male hormones might explain the greater number of
>males than females at the low end of many ability distributions, but does not
>explain the greater number of males at the high end of these distributions.

It has also been suggested that males are more sensitive to the environment,
poor environment = negative impact, good environment = positive impact - this
view may explain the greater variability in the male distribution.

>The greater variability in the reproductive success of males, relative to
>females,
>might have created pressures for males who were not successful in
>modal forms
>of intramale competition to develop alternative reproductive
>strategies (Le Boeuf
>1974).
>It seems that there are many different routes to high status for males.
>Presumably, different routes to high status would have led to different
>patterns of
>cognitive abilities being selected for in males who used
>different reproductive
>strategies.

These factors may also have led to greater variability within the males,
thereby offering an explanation for the wider distribution.

>.. sexual selection and its consequences might be one theoretical perspective
>from which the issue of the sex difference in intrasexual variability can be
>addressed. Second, sex differences in the distributions of cognitive
>abilities has
>important implications for interpreting mean sex differences in
>mathematical
>abilities, because mathematics is a domain where a consistent
>sex difference in
>variability is found; males are more variable than females
>(e.g., Feingold 1992).

The need to understand variability in sex differences is as important as
understanding the mean sex differences because of the variation in the number
of males and females at each end of the ability distributions. There is also
a need to relate these differences to mathematical abilities because of the
consistent sex difference in variability found in this area.



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