寿命是哺乳动物普遍存在的现象,欧美及日本平均寿命男女均延长到70～80岁,但能生存到100岁以上者仍然很低。Sacher 提出的经验式人类寿命界限是10.8×(脑重量)0.636/(体重)0.225(克),提示脑组织的重要性,也很符合实际。有关细胞老化问题,Hayflick 及Moorhead观察到人成纤维细胞倍化次数如超过38～60次则停止增殖。Martin 等认为成纤维细胞供体的年龄越大细胞倍化次数越少,提示细胞增殖次数有限。Wright 及Hayflick 做细胞融合实验显示年轻细胞质和老化核融合细胞的倍化次数与老化细胞水平相同,但老化细胞质和年轻 Life expectancy is a common phenomenon in mammals. The average life expectancy in Europe, the United States and Japan is extended to 70 to 80 years of age, but those who survive over 100 years of age are still low. Sacher’s exponential human life expectancy is 10.8 × (brain weight) 0.636 / (body weight) 0.225 (grams), suggesting the importance of brain tissue is also realistic. Concerning cell aging, Hayflick and Moorhead observed that if the number of human fibroblasts is more than 38 to 60, the proliferation stops. Martin et al think that the larger the age of donor of fibroblasts, the smaller the number of cell doublings, suggesting that the number of cell proliferation is limited. Wright and Hayflick cell fusion experiments showed that young cytoplasm and aging nuclear fusion cells doubling times the same level as aging cells, but aging cytoplasm and young