The principles of sexual selection were used as an organizing framewor
k for interpreting cross-national patterns of sex differences in mathe
matical abilities. Cross-national studies suggest that there are no se
x differences in biologically primary mathematical abilities, that is,
for those mathematical abilities that are found in all cultures as we
ll as in nonhuman primates, and show moderate heritability estimates.
Sex differences in several biologically secondary mathematical domains
(i.e., those that emerge primarily in school) are found throughout th
e industrialized world. In particular, males consistently outperform f
emales in the solving of mathematical word problems and geometry. Sexu
al selection and any associated proximate mechanisms (e.g., sex hormon
es) influence these sex differences in mathematical performance indire
ctly. First, sexual selection resulted in greater elaboration in males
than in females of the neurocognitive systems that support navigation
in three-dimensional space. Knowledge implicit in these systems refle
cts an understanding of basic Euclidean geometry, and may thus be one
source of the male advantage in geometry. Males also use more readily
than females these spatial systems in problem-solving situations, whic
h also appear to be related in part to sexual selection, result in sex
differences in engagement in mathematics-related activities, thus fur
ther increasing the male advantage in certain mathematical domains. A
model that integrates these biological influences with sociocultural i
nfluences on the sex differences in mathematical performance is presen
ted in this article.