Two recent studies by Parisi et al.1 and Ranz et al.,2 catalogue sex differences in gene expression across the whole genome of the fruit fly Drosophila melanogaster. Both report striking associations of sex‐biased gene expression with the X chromosome. Genes with male‐biased expression are depauperate on the X chromosome, whereas genes with female‐biased expression show weaker evidence of being in excess. A number of evolutionary hypotheses for the expulsion or exclusion of male‐biased genes from the X chromosome have been suggested. (...) None is entirely consistent with the available evidence. BioEssays 25:739–741, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Eminent psychologists were asked to reflect on their work and discuss the basic tenets of beliefs of their psychologies and how they arrived at them. The result is this fascinating collection. Contributors discuss subject matter for psychology, what findings they are most certain of, the best methods to study research problems, and what direction the field will take in the future.