Elizabeth Pollitzer's point about sex mattering in all areas of biology has long been considered an important topic (see Nature 500, 23–24; 2013).

For example, the Endocrine Society's flagship journal Endocrinology, of which I am editor-in-chief, has since 2012 required authors to include the sex of animals, tissues and even cell lines in their papers (J. D. Blaustein Endocrinology 153, 2539–2540; 2012). Authors must justify the use of single-sex animals or tissues, and consider sex in interpreting their data.

Research in neurobiology and psychology has also consistently recognized sex differences in physiology, pathophysiology, pharmacology and toxicology (see, for example, G. E. Gillies & S. McArthur Pharmacol. Rev. 62, 155–198; 2010). The US National Institutes of Health supports such research and has emphasized its importance in programme announcements.

From 1922, the US Committee for Research in Problems of Sex was funded by the Rockefeller Foundation for decades. In 2006, the Organization for the Study of Sex Differences, based in Atlanta, Georgia, was founded for researchers and clinicians.

Studies on sex differences published before the PubMed online archive, electronic journals and searchable keywords should not be overlooked.