Young men are more distressed by a partner’s sexual infidelity, whereas young women are more distressed by a partner’s emotional infidelity. The present research investigated (a) whether the sex difference in jealousy replicates in an older sample, and (b) whether younger people differ from older people in their selection of the more distressing infidelity scenario. We presented forced-choice dilemmas to 202 older people (mean age = 67 years) and to 234 younger people (mean age = 20 years). The sex difference (...) replicated in the older sample. In addition, older women were less likely than younger women to select a partner’s emotional infidelity as more distressing than a partner’s sexual infidelity. Discussion offers directions for future work on sex differences and age differences in jealousy. (shrink)

According to Williams, human facially expressed pain, and its perception by conspecifics, is generated by evolved mechanisms. We argue that a key variable – sex (male, female) – needs to be considered for a complete theory of pain expression and perception. To illustrate, we cite findings on sex differences in pain and pain perception, and in crying and crying responsiveness.

Integration of different lines of research concerning grandparental investment appears to be both promising and necessary. However, it must stop short when confronted with incommensurate arguments and hypotheses, either within or between disciplines. Further, some hypotheses have less plausibility and veridicality than others. This point is illustrated with results that conflict previous conclusions from evolutionary psychology about differential grandparental investment.

Blair's assertion that fluid intelligence (gF) is distinct from general intelligence (g) is contradictory to cumulative evidence from intelligence research, including extant and novel evidence about generational IQ gains (Lynn–Flynn effect). Because of the near unity of gF and g, his hypothetical concept of gF' (gF “purged” of g variance) may well be a phlogiston theory. (Published Online April 5 2006).

Suicidal behavior is an interesting blank space in Keller & Miller's (K&M's) population genetical account on explaining the existence and persistence of common, harmful, heritable mental disorders. I argue that suicidal behavior is yet another of these disorders. It may well be consistent with all three evolutionary models considered by K&M. (Published Online November 9 2006).

Simpson and Gangestad's (1991) Sociosexual Orientation Inventory (SOI) is pivotal in Schmitt's cross-national study on sociosexuality. Here I elaborate on psychometric shortcomings of the SOI that are crucial in this research context.

According to Roberts, self-experimentation is a viable tool for idea generation in the behavioral sciences. Here we discuss some limitations of this assertion, as well as particular design and data-analytic shortcomings of his experiments.

Augmenting and supplementing the arguments of Crespi & Badcock (C&B), I show that digit ratio (2D:4D), a putative marker of prenatal androgen action, indeed appears differentially altered in autism-spectrum disorders (lower/masculinized) versus schizophrenic-spectrum disorders (higher/feminized). Consistent with C&B's framework, some evidence (substantial heritability, assortative mating, sex-specific familial transmission) points to possible sex chromosome and imprinted genes effects on 2D:4D expression.