Wouldn't that be sex, not love?
Well, love can often lead to sex, so eh~
Love is one, sexual gratification is another.
Sex alone is nothing but "egg × sperm = division by googol", rather boring really. :|
Hmm, I forgot other interpretations of "love". So, for the thread now, I continue:
Love like that of a mother for her child. A Mechanism to have the parent care for their child, even if it's a horrible little brat. :O
Love as friendship. Teamwork mechanism in humans; we once hunted like packs of wolves, and for that, knowing one's fellow hunters would indeed be helpful. Also, as people make circles of friends, they share amongst eachother, ensuring no one is left hungry, cold etc. — how many times have you asked your friend for a piece of their chocolate bar?
Love for objects. Unless you have a paraphilia involving man-made objects, this may as well be a different word (give it a few thousand years and it may end up spelt and/or pronounced differently) since it's just a liking towards whatever object, perhaps because it tastes nice. There's no "like, liker and likest" so 'love' makes a decent already familiar term to use in such a case.