Dr Tom Smith: Why do women live longer than men?

Females are born with a big advantage over feeble males. The Y-chromosome that differentiates men from women carries little else but sex chromatin - the stuff that gives them dangly bits. On the other hand, women's extra X chromosome carries a host of goodies other than sex proteins, including extra strands to their immune systems that make them less susceptible to a host of illnesses. That's partly why, on average, women have heart attacks and strokes 10 years later than men. Men start to die from them in their 50s and 60s, women from their mid-60s. As a rule, women should live five years longer than men.

Can people be kept alive with no heartbeat or breath, then brought back to life undamaged?

In 1999, Anna Bagenholm fell through river ice and was brought out of the water 80 minutes later. She had no heartbeat and was not breathing. Her body temperature was more than 20 degrees below normal. However, she hadn't drowned. Hitting her head had stopped her inhaling water and she was almost instantly frozen. Her blood was removed, warmed up and fed back into her veins. She recovered, with no long-term ill-effects. Surgeons are considering low-temperature techniques to operate on seriously injured people - this will avoid the use of vast amounts of blood and should save lives that would otherwise be lost. The problem is getting informed consent from people who are badly injured; we may have to carry consent cards .

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