A study led by the University of Michigan in the United States reviewed the genetic and health information of over 276000 people, providing strong support for a decades old evolutionary theory - the Williams hypothesis. The research findings are published in the latest issue of the journal Scientific Progress. In 1957, evolutionary biologist George Williams proposed that if genetic mutations that cause aging in early life are beneficial for promoting early reproduction or producing more offspring, they may be favored by natural selection. Williams' idea is now known as the hypothesis of antagonistic pleiotropy in aging, although supported by individual case studies, lacks clear genome-wide evidence. A new study has found a strong negative correlation between reproduction and lifespan in genes, which means that gene mutations that promote reproduction often shorten lifespan. In addition, according to the study, individuals carrying mutations that cause their fertility rates to be relatively low are less likely to live to the age of 76 compared to those carrying mutations that cause their fertility rates to be relatively high. However, researchers warn that both reproduction and lifespan are influenced by both genes and the environment. Compared to environmental factors (including the impact of contraception and abortion on reproduction, as well as the impact of medical progress on lifespan), the role of genetic factors discussed in the study is relatively small. The research findings provide strong support for Williams' hypothesis that aging is a byproduct of natural selection. Natural selection rarely cares about how long humans can survive after reproduction, while human health is largely determined at the end of reproduction. Interestingly, research has found that having only two children is beneficial for having the longest lifespan when controlling for gene predicted reproduction quantity and time. The fewer or more children one has, the shorter their lifespan will be. (Lai Xin She)