任何生物在个体发育的最后阶段,都要进入衰老。衰老是生物体在正常环境条件下,机能的进行性减退,逐渐趋向死亡的现象。凡是自然死亡,都正如恩格斯所说的“死亡不是一个突然事件,而是一个长期的过程”。同一个人,每一瞬间都处在不断的产生与衰亡之中。当然,衰老过程的长短是相对的,可塑性很大,蜉蝣成虫朝生暮死,而澳州的苏铁树已经活了一万二千多年。 Any creature enters aging in the final stages of individual development. Aging is the organism under normal environmental conditions, the progressive decline in function, and gradually toward the phenomenon of death. All natural deaths, just as Engels said, “death is not a sudden event, but a long-term one.” The same person, every moment is in constant production and decline. Of course, the length of the aging process is relative and the plasticity is very high. Adult Sumatrans are dying, while the Cycas in Australia has lived for more than 12,000 years.