An ancillary effect of extended care for the young could be that humans have a powerful propensity for attachment and thus also strongly attach to nonkin who become friends, neighbors or spouses.

• 长时间照顾年轻人的连带结果是，人类有著强烈的情感倾向，因此也对非亲属关系的朋友、邻居或配偶有著强烈的情感。