The functional approach doesn't work for love imo. For survival of humanity, f*** around would suffice, but love has too many drawbacks to be regarded as nothing but a necessary foundation of community.Also, if you view it from your "evolutionary", (sorry, but: pseudo-)scientific angle, why would you differentiate between emotion and chemicals?
Sure about that? The reason we form family units is probably because our babies take a long time to become even remotely self-sufficient.
This is obviously pseudo-science as I don't actually know anything about this subject, but it does seem resonable. Or do we have examples in the animal world of mothers taking care of babies for 1.5 decade before the baby is reasonably self-sufficient?