If there are any men left who still believe that women are the weaker sex, it is long past time for them to think again. With respect to that most essential proof of robustness—the power to stay alive—women are tougher than men from birth through to extreme old age. The average man may run a 100-meter race faster than the average woman and lift heavier weights. But nowadays women outlive men by about five to six years. By age 85 there are roughly six women to every four men. At age 100 the ratio is more than two to one. And by age 122—the current world record for human longevity—the score stands at one-nil in favor of women.