Sincere Relationships

There's nothing like being in love. Minutes seem to creep and fly at the same time. We get lost on the way home, thinking of the next date. Music cries out to us alone, and the full moon winks our way. Long after other memories fade, the recollection of love lingers. It's pure magic. Or at least that's what we like to tell ourselves.

For all the advances scientists are making deciphering the biology of love--for all the circuitry appearing in brain scans and the chemistry emerging in blood and scent studies--we still want to believe that science will never tame romance. We're sure that it will always remain utterly separate from the cells and organs and reflexes that biologists study. And indeed, how could anything that so moves us to poetry and song be so reducible to behavior and chemicals?

Charles Darwin started wrestling with questions like this when he published his 1871 book The Descent of Man. Darwin granted that his readers might doubt that humans evolved from an ancestral ape. "Man differs so greatly in his mental power from all other animals, there must be some error in this conclusion," he wrote. But he argued that the difference between us and other animals was of degree, not of kind. That applied not just to our teeth and toes but also to our morals and minds. And even, he declared, to love.

Over the past 137 years, scientists have learned again and again the value of Darwin's perspective. One of the best ways to appreciate what it means to be human is to learn about how human abilities came to be. No other species uses full-blown language, for example. But animal communication is surprisingly complex. Primates in particular are able to do a lot of the mental tasks that are essential to grasping language. Regions of the brain