6.A Long and Healthy Life Have you wished for a magic pill or magic formula (方法) that would let you live happily forever ? If you have, don’t feel alone! It’ s a very common, natural wish that has a long history. Spanish explorers of the sixteenth century even tried to find a fountain of youth in what is now the state of Florida. The water of this legendary (传说中的) fountain, which no one has yet found ,was believed to restore youth and good health to those who drank it. Biologists today don’ t expect that anyone will find a magical fountain of youth. Growing older is a natural part of the life cycle that can’ t be reversed(倒退) .As human beings grow older ,organs such as the heart and lungs may stop functioning properly. Sight and hearing may become weak .And the human body becomes more likely to come down with serious illness from which it cannot recover. Considered together, changes that bring about the decline(衰退) of an organism are called aging .Because of aging ,many biologists believe that there may be a maximum(最大的) age limit to which even the healthiest organisms can live. For human beings, this maximum age limit is about 110 years. Perhaps the most important thing that you can learn from your study of human biology is that you have a lot of control over the aging process in your own life .In fact; within our control are many physical and mental factors that have much to do with aging. For example ,each of us ,as recent research indicates, can do many things to help prevent heart and vessel(血管) disease ,which causes half the deaths each year in the United States .We can avoid eating a lot of fatty meat. Eating too much of these types of anima...
