Riggs J E
Department of Neurology, West Virginia University School of Medicine, Morgantown 26506-9180, USA.
Mech Ageing Dev. 1996 Dec 20;92(2-3):111-20. doi: 10.1016/s0047-6374(60)01830-7.
Evidence for natural selection is often presented from the perspective of evolution. However, evolution is not the purpose of natural selection. Natural selection might also impact upon the manifestation of senescence via differential survival. The relationship between age-specific cancer mortality rates and corresponding age group population size in the USA from 1951 to 1989 for age groups over age 45 was examined. Rising age-specific cancer mortality rates among elderly men were increasingly correlated with growing age group population size with increasing age. This relationship was not observed in women. Since an age-specific rate should be independent of age group population size, this finding suggests that successive cohorts of elderly USA men were not comparable with respect to their susceptibility to cancer mortality. Differential survival, which effects men more than women, and its selective culling effect upon the surviving gene pool in an aging population may account for some of the observed increasing cancer mortality rates among elderly men. If so, evidence of natural selection can also be presented from the perspective of manifestation rates for some disorders associated with senescence.
自然选择的证据通常是从进化的角度呈现的。然而，进化并非自然选择的目的。自然选择也可能通过差异生存影响衰老的表现。研究了1951年至1989年美国45岁以上年龄组特定年龄癌症死亡率与相应年龄组人口规模之间的关系。老年男性中特定年龄癌症死亡率的上升与年龄组人口规模的增长以及年龄的增加越来越相关。在女性中未观察到这种关系。由于特定年龄率应与年龄组人口规模无关，这一发现表明，美国老年男性的连续队列在癌症死亡率易感性方面不具有可比性。差异生存对男性的影响大于女性，以及其对老龄化人口中存活基因库的选择性淘汰作用，可能是观察到的老年男性癌症死亡率上升的部分原因。如果是这样，自然选择的证据也可以从与衰老相关的某些疾病的表现率角度呈现。
