he urge to select children's sex is not new. The Babylonian Talmud, a Jewish text completed towards the end of the fifth century of the Christian era, advises couples on means to favour the birth of either a male or a female child. 1 The development of amniocentesis alerted the public in the mid-1970s to the scientific potential for prenatal determination of fetal sex, 2 and progressive decrimi...

For centuries, couples have tried to choose the sex of their children. Italian men bit their wife’s left ears during intercourse to beget daughters; Swedish men hung their pants on the right bedpost to father boys; while German woodcutters took their axes to bed and chanted: “Ruck, ruck, roy, you shall have a boy!” or “Ruck, ruck, raid, you shall have a maid!” Sex selection is now a reality. Th...

Sexually dimorphic phenotypes are thought to largely result from sex differences in gene expression, and genes with sex-biased expression have been well characterized in adults of many species. Although most sexual dimorphisms manifest in adults, many result from sex-specific developmental trajectories, implying that juveniles may exhibit significant levels of sex-biased expression. However, it...

Delving into the literature on the evolution of sex is like picking up a dusty, old, unpromising book and discovering that a fascinating mystery novel lies within it. What makes this tome unpromising is that explaining the evolution of sex seems so trivial at first. Isn't it obvious that sex generates variation ? The fact that nearly all eukaryotes engage in sex, at least occasionally , reinfor...