我为什么存在? 祖母才是人类进化的关键_BEC初级作文

我为什么存在? 祖母才是人类进化的关键

But that immaturity has a cost. It means that biological mothers can't keep babies going all by themselves: They need help. In forager societies grandmothers provide a substantial amount of child care as well as nutrition. Barry Hewlett at Washington State University and his colleagues found, much to their surprise, that grandmothers even shared breast-feeding with mothers. Some grandmoms just served as big pacifiers, but some, even after menopause, could 'relactate,' actually producing milk. (Though I think I'll stick to the high-tech, 21st-century version of helping to feed my 5-month-old granddaughter with electric pumps, freezers and bottles.)

但这种不成熟有其代价。它意味着生物学意义上的母亲无法完全靠自己带孩子：她们需要帮手。在狩猎采集社会，祖母不仅提供营养，也做了大量的育儿工作。华盛顿州立大学(Washington State University)的巴利・休利特(Barry Hewlett)及其同事非常意外地发现，祖母甚至和母亲共同哺乳。一些祖母仅仅是充当大奶嘴的作用，但有些祖母甚至在更年期过后都能“重新哺乳”(relactate)，真的会分泌乳汁。（不过我想我自己会坚持采用21世纪的高科技方法，用电泵、冰箱和奶瓶来帮助喂养五个月大的孙女。）

Dr. Hawkes's 'grandmother hypothesis' proposes that grandmotherhood developed in tandem with our long childhood. In fact, she argues that the evolution of grandmothers was exactly what allowed our long childhood, and the learning and culture that go with it, to emerge. In mathematical models, you can see what happens if, at first, just a few women live past menopause and use that time to support their grandchildren (who, of course, share their genes). The 'grandmother trait' can rapidly take hold and spread. And the more grandmothers contribute, the longer the period of immaturity can be.