Well yes, but that was never the claim.
I found this report last night which is quite relevant to the debate:
Intelligence: Knowns and Unknowns
Report of a Task Force established by the Board of Scientific Affairs
of the American Psychological Association (Released August 7, 1995)
http://www.csra.net/lrand/APA_01.htm
It is mostly about "The Bell Curve" but contains this section:
Sex Differences
Most standard tests of intelligence have been constructed so that
there are no overall score differences between females and males.
Some recent studies do report sex differences in IQ, but the direction
is variable and the effects are small (Held, Alderton, Foley, & Segall,
1993; Lynn, 1994). This overall equivalence does not imply equal
performance on every individual ability. While some tasks show no sex
differences, there are others where small differences appear and a few
where they are large and consistent.
Spatial and quantitative Abilities. Large differences favoring males
appear on visual-spatial tasks like mental rotation and spatio-temporal
tasks like tracking a moving object through space (Law, Pellegrino, &
Hunt, 1993; Linn & Petersen, 1985). The sex difference on mental
rotation tasks is substantial: a recent meta-analysis (Masters &
Sanders, 1993) puts the effect size at d = 0.9. (Effect sizes are
measured in standard deviation units. Here, the mean of the male
distribution is nearly one standard deviation above that for females.)
Males' achievement levels on movement-related and visual-spatial tests
are relevant to their generally better performance in tasks that involve
aiming and throwing (Jardine & Martin, 1983).
Some quantitative abilities also show consistent differences. Females
have a clear advantage on quantitative tasks in the early years of
school (Hyde, Fennema, & Lamon, 1990), but this reverses sometime
before puberty; males then maintain their superior performance into
old age. The math portion of the Scholastic Aptitude Test shows a
substantial advantage for males (d = 0.33 to 0.50), with many more
males scoring in the highest ranges (Benbow, 1988; Halpern, 1992).
Males also score consistently higher on tests of proportional and
mechanical reasoning [Meehan, 1984; Stanley, Benbow, Brody, Dauber,
& Lupkowski, 1992).
Verbal Abilities. Some verbal tasks show substantial mean differences
favoring females. These include synonym generation and verbal fluency
(e.g., naming words that start with a given letter), with effect
sizes ranging from d = 0.5 to 1.2 (Gordon & Lee, 1986; Hines, 1990).
On average females score higher on college achievement tests in
literature, English composition, and Spanish (Stanley, 1993) they also
excel at reading and spelling Many more males than females are diagnosed
with dyslexia and other reading disabilities (Sutaria, 1985), and there
are many more male stutterers (Yairi & Ambrose, 1992). Some memory tasks
also show better performance by females, but the size (and perhaps even
the direction) of the effect varies with the type of memory being
assessed.
Causal Factors. There are both social and biological reasons for these
differences. At the social level there are both subtle and overt
differences between the experiences, expectations, and gender roles of
females and males. Relevant environmental differences appear soon after
birth. They range from the gender-differentiated toys that children
regularly receive to the expectations of adult life with which they are
presented, from gender-differentiated household and leisure activities
to assumptions about differences in basic ability. Models that include
many of these psychosocial variables have been successful in predicting
academic achievement (Eccles, 1987).
Many biological variables are also relevant. One focus of current research
is on differences in the sizes or shapes of particular neural structures.
Numerous sexually dimorphic brain structures have now been identified, and
they may well have implications for cognition. There are, for example, sex
related differences in the sizes of some portions of the corpus callosum;
these differences are correlated with verbal fluency (Hines, Chiu, McAdams,
Bentler, & Lipcamon, 1992). Recent brain imaging studies have found what
may be differences in the lateralization of language (Shaywitz et al., 1995).
Note that such differences in neural structure could result from differences
in patterns of life experience as well as from genetically-driven mechanisms
of brain development; moreover, brain development and experience may have
bi-directional effects on each other. This research area is still in a
largely exploratory phase.
Hormonal Influences. The importance of prenatal exposure to sex hormones
is well established. Hormones influence not only the developing genitalia
but also the brain and certain immune system structures (Geschwind &
Gaiaburda, 1987; Halpern & Cass, 1994). Several studies have tested
individuals who were exposed to abnormally high androgen levels in utero,
due to a condition known as congenital adrenal hyperplasia(CAH). Adult CAH
females score significantly higher than controls on tests of spatial
ability (Resnick, Berenbaum, Gottesman & Bouchard, 1986); CAH girls play
more with "boys' toys" and less with 'girls' toys" than controls (Berenbaum
& Hines, 1992).
Other experimental paradigms confirm the relevance of sex hormones for
performance levels in certain skills. Christiansen and Knussman (1987)
found testosterone levels in normal males to be correlated positively
(about .20) with some measures of spatial ability and negatively
(about -.20) with some measures of verbal ability. Older males given
testosterone show improved performance on visual-spatial tests (Janowsky,
Oviatt, & Orwoll, 1994). Many similar findings have been reported, though
the effects are often non-linear and complex (Gouchie & Kimura, 1991;
Nyborg, 1984). It is clear that any adequate model of sex differences in
cognition will have to take both biological and psychological variables
(and their interactions) into account.
== end quoted material ==
So if de Garis defines genius narrowly to mathematical or scientific
genius (which I would personally disagree with), then this report seems
to support his claim to some extent. However I suspect that other factors
such as social barriers to entry in scientific fields, and possible
genetic predispositions away from status-seeking endeavors like
academic ladder climbing have at least as much to do with the phenomenon.
Interestingly (and my PC alarms are going off for even mentioning it)
the report has this to say about racial differences:
"The differential between the mean intelligence test scores of Blacks and
Whites (about one standard deviation, although it may be diminishing) does
not result from any obvious biases in test construction and administration,
nor does it simply reflect differences in socio-economic status. Explanations
based on factors of caste and culture may be appropriate, but so far have
little direct empirical support. There is certainly no such support for a
genetic interpretation. At present, no one knows what causes this
differential."
-- David McFadzean david@kumo.com Memetic Engineer http://www.kumo.com/~david/ Kumo Software Corp. http://www.kumo.com