Another traditional usefulness of older people is that they are capable of babysitting their grandchildren, thereby freeing up their own adult children, the parents of those grandchildren, to go hunting and gathering food for the grandchildren.
また 高齢者が 孫の面倒を見られれば 社会とって有用です 孫の親にあたる — 子供達の世代が 孫のために 自由に狩りや 食料採集に行けるからです