Spatial and mathematical abilities may be “sex-limited” traits. A sex-limited trait has the same determinants of variation within the sexes, but the genetic or environmental effects would be differentially expressed in males and females. New advances in structural equation modeling allow means and variation to be estimated simultaneously. When these statistical methods are combined with a genetically informative research design, it should be possible to demonstrate that the genes influencing spatial and mathematical abilities are sex-limited in their expression. This approach (...) would give an empirical confirmation of Geary's evolutionary speculations. (shrink)

Geary suggests that implicit mathematical principles exist across human cultures and transcend sex differences. Is such knowledge present in animals as well, and is it sufficient to account for performance in all species, including our own? I attempt to trace the implications of Gearys target article for comparative psychology, questioning the exclusion of “subitizing” in describing human mathematical performance, and asking whether human researchers function as cultural agents with animals, elevating their implicit knowledge to secondary domains of numerical performance.

The beginning of any rigorous interdisciplinary study, as Hegel and later Marx predicted, is going to be the occasion for opposition, contradiction, negation and mediation. Sociobiology is not a mature field (thesis). Kitcher's critical work entitledVaulting Ambition seeks to at once expose the failings of this field (serving as antithesis) while simultaneously defining the requirements for more mature, and thus epistemologically satisfying, sociobiological explanations (synthesis). The sociobiological research agenda is thus implicitly given a green light provided certain methodological precautions are (...) taken into consideration. Confucius believed that under these circumstances the only way to restore order would be so to arrange affairs that the Emperor would continue to be Emperor, the nobles to be nobles, the ministers to be ministers, and the common people common people. That is, the actual must in each case be made to correspond to the name. This theory Confucius called theRectification of Names (cheng ming), a doctrine which he recognized as being of the utmost importance. (Fung, 1952, p. 59). Tzu-lu said, “If the Lord of Wei left the adminstration (cheng) of his state to you, what would you put first?” The Master said, “If something has to be put first, it is, perhaps, the rectification (cheng) of names.” (The Analects (Lun yü) of Confucius, Book XIII: 3) (Besides being homophones, the two words in Chinese are cognate, thus showing that the concept of ‘governing’ was felt to be related to that of ‘correcting’.) . (shrink)

This article is divided into two main sections. The first discusses “Female Inheritance and the Male Retention Hypothesis.” Permanent groups (groups with no inherent limit on group longevity) exist in several species because over generations members share important interests. Considering the association between cooperation and degree of relatedness, it seems to follow that a collective interest is more likely to be achieved when members show a higher degree of relatedness. I argue that if membership is inherited by only one sex, (...) and this is the female sex, this results in a higher degree of relatedness between group members than when membership is inherited by both sexes, or by males only. Indeed, this is found in the overwhelming majority of species of insects, fish, birds, and mammals living in permanent groups. The (few) exceptions to the rule are briefly discussed. Humans are of special interest because human preindustrial societies tend to show either male or female inheritance. The second section asks, “Do Moralizing Gods Raise Paternity Confidence?” Since males inherit valuable membership in patrilocal/lineal societies, they are expected to be more concerned about the probability of paternity than males in matrilocal/lineal societies. Moral rules, and specifically belief in moralizing gods, are expected to reflect this difference. An analysis of cross-cultural data of preindustrial societies does not refute the hypothesis that moralizing gods are more often found in patrilocal/lineal societies, nor is this hypothesis unambiguously supported. (shrink)

I have provided evidence that Geary's model does not explain male dominance in spatial abilities by sexual selection. The current literature concerning the relations of nonverbal IQ to testosterone, hand preference, and right- and left-hand skill, as well as the organizing effects of testosterone on cerebral lateralization during the perinatal period, does not support Geary's arguments.

Geary's project faces the severe methodological difficulty of tracing the biological effects of gender on mathematical ability in a system that is massively open. Two methodological stratagems he uses are considered. The first is that pancultural sex differences are biological in nature, which is dubious in the domain of mathematics, since it is completely culture-bound. The second is that sociosexual differences are partly caused by biosexual differences, which renders his thesis unfalsifiable and empirically empty.