Editorial: Sex ratios in the Anthropocene

Sex ratios.

Jennions et al. introduce the different kinds of sex ratio and their biology.

Sex ratios in primate groups

Changing sex ratios in diabetes.

A survey of sexes and ages in patients attending the Hartlepool diabetic clinic was carried out for the 20-year period 1948-67. The proportion of men aged 50 and over rose from 25.9% in the first decade to 38.2% in the second. An attempt has been made to explain this pronounced and rapid change.

Declining sex ratios in Canada.

OBJECTIVE To examine the trends in the proportion of annual live births that were male in Canada and to compare the trends with those in the United States. DESIGN Analysis of census data. SETTING Canada as a whole and 4 main regions (West, Ontario, Quebec and Atlantic). SUBJECTS All live births from 1930 to 1990. OUTCOME MEASURES Sex ratio (expressed as the proportion of total live birt...

Distorting sex ratios.

D uring sperm production in mammals, the process of meiosis generates sper-matozoa that are genetically different but functionally equivalent. So, with respect to the sex chromosomes, for example, equal numbers of sperm are produced carrying either an X or a Y chromosome. Because X and Y sperm are equally capable of fertilizing an egg, equal numbers of male and female embryos are produced, and ...