Books for Valentine's Day: 'Science of Kissing' and more

'Oh no," you groan. "Can't the scientists keep their grubby paws off the last of life's great mysteries, the power of the kiss?" Stop whining. It turns out they have, oddly, failed to really find out why it makes us feel the way we do. Sheril Kirshenbaum, a Discover magazine blogger, cheerfully steps up to the plate with "The Science of Kissing: What Our Lips Are Telling Us" (Grand Central, $19.99). "I promise, the knowledge won't take any of the magic away," she writes, a kind nurse administering a dose of reality. Kirshenbaum interviews neuroscientists, endocrinologists and anthropologists; she pores through studies.

But first, Kirshenbaum takes a brief tour through history. Kissing is first documented in 1500 BC in the Vedic texts of India, in which lovers set "mouth to mouth." Then there's the Old Testament, the Babylonians, the Romans, the Norse myths, the Druids. There's no stopping it, though in many cultures it was, and still is, forbidden in public.

Many of Kirshenbaum's findings are, in fact, mood killers, but look - we've eaten of the tree of knowledge, and there's no going back. It turns out we humans have always liked red (the color of fruit) and things that stick out from the body. Freud (that buzzkill) chimes in with theories of sucking and "breast deprivation." There's a lot of information about sniffing and kissing as a way to gather information on a potential mate. There's the transfer of hormones and, yes, cooties. Is the magic gone yet? You tell me.

Fiction, ever the realm of the heart, delivers where nonfiction fails. With "The Lover's Dictionary" (Farrar, Straus and Giroux, $18), David Levithan has written a love story, the narrator's own, in dictionary format. One is normally suspicious of books with funky rubrics - they often mask poor writing - but "The Lover's Dictionary" is clever and poetic and, sigh, sad.

Let's not mince words: That idiot didn't know what she had. They meet through an online dating service, and the novel begins with the word "aberrant, adj. 'I don't normally do this kind of thing,' you said. 'Neither do I,' I assured you. . . . Measure the hope of that moment, that feeling. Everything else will be measured against it." They are together two years. She doesn't put the cap on the toothpaste, and she steals the covers at night. She drinks too much. He has faults, too. But they are in it together, a pair, until she blows it. "Neophyte, n. There are millions upon millions of people who have been through this before - why is it that no one can give me good advice?"

The brief entries are like poetry; poetry with a gravitational pull back to the central narrative, which is two people falling in love. The fact that the pieces hold together so well is testament, not only to Levithan's light hand and gracious writing but also to the power of this universal story.

In 1987, Deb Olin Unferth fell completely, selflessly in love with George. She was a college freshman, just 18; George was a senior working on a thesis on liberation theology. Now we've all known a George - the charismatic autodidact; the fast-talking, philosophizing, let's-just-do-it guy who inspires followers. In "Revolution: The Year I Fell in Love and Went to Join the War" (Henry Holt, $24), Unferth recounts how she follows George to El Salvador and converts from Judaism to Christianity. They are fired from their first job, at an orphanage, because Deb refuses to wear a bra. They are fired from their next job, in Nicaragua. They are no good at this revolution thing. George proposes and she accepts - but dreads the prospect of this life with George.

Unferth writes with a beautiful insouciance. All the details are not necessary; we readers know the general score. It's the unique moments that are so important, like when she realizes that George, unlike anyone else in her life, is actually loyal to her. "The situation, I explained, had come to a point where I could no longer not say that I loved him. . . . And then I pulled part of my dress over my head. (I used to do that.) And he said, 'Come out of there' (he used to say that), and tugged at my dress until I came out." Two kids. What could be more beautiful?

It didn't work out with George, as you might have guessed. But years later and happily married, Unferth writes this story and, yes, looks for George. Not to rekindle anything but because - and this is good and bad news - love doesn't go away. It just doesn't go away - it changes into something else. Amen. And Happy Valentine's Day.