Why sex bias in labs means women are the losers in research into ageing

In laboratories worldwide cages are filled with mice who share a striking similarity: they are all male, say experts

• Study suggests drug could extend women's fertility by five years

Extending the human lifespan is a multibillion-pound industry and has been hailed as the most fascinating scientific challenge in modern history. But if a drug to achieve longevity is ever discovered, one thing looks certain: it is highly unlikely to work on women - and almost inconceivable that it will work on mothers.

That is because, say experts, cages in laboratories across the world are filled with white mice who share a striking similarity: they are all male.