We're social animals. Anything that benefits the extended tribal unit is advantageous. Adults beyond child-bearing age contribute significantly to child raising

We're social animals. Anything that benefits the extended tribal unit is advantageous. Adults beyond child-bearing age contribute significantly to child raising, education, leadership etc of the entire tribe. Similar effects are seen in other species https://www.nature.com/articles/s41467-018-05515-8 https://www.nature.com/articles/s41467-018-05515-8