From The New York Times:
The news about love — if anything can be said to be new when it comes to love — is that it affects us on more levels than we realized. Poets and artists have long viewed love as a prime mover, but by the beginning of the last century, scientists and philosophers were dismissing it as socially and scientifically irrelevant. Love was confined to private life, where only women and novelists and psychoanalysts were supposed to pay much attention to it. Then, a little more than half a century ago, biologists and economists and psychologists decided that love mattered after all, and began conducting experiments to determine how much.
The early science of love looks a little shocking in retrospect. Experiments meant to demonstrate that mammals attach themselves to mothers because they need love, not just food, all too often required outright torture. Researchers snatched baby creatures away from mother creatures and put them in cages to prove that life without love was a sad, diminished thing. The science of sexual attraction made use of more benign methods, but until more women entered the field and started asking different questions, the experiments tended to produce stunning affirmations of Western patriarchal stereotypes. Whatever the results, however, this work did make scientists appreciate the central importance of love for life. Love or the lack of it turned out to affect not just psyches but also bodies; not just brains and genitals but also hormones and the expression of genes; not just the well-being of individuals but also the flourishing of societies.