Both men and women are living longer these days in industrialized countries． (1) In general，they can expect to live six or seven years more than men．One reason for this is biological．
One important biological factor that helps women live longer is the difference in hormones between men and women．(2) Between the ages of about 12and 50，women produce hormones that are involved in fertility（生育能力）．These hormones also have a positive effect on the heart and blood flow．In fact，women are less likely to have high blood pressure or to die from heart attacks．
(3)They help the body defend itself against some kinds of infections．This means that women generally ger sick less often and less seriously than men．The common cold is a good example：women，on average，get fewer colds than men．(4)Scientists are still not exactly sure how genes influence aging，but they believe that they do．Some think that a woman’s body cells have a tendency（向） to age more slowly than a man’s．Others think that a man’s body cells have a tendency to age more quickly．(5)