THERE are millions of Americans seeking love on the Internet. Little do they know that teams of scientists are eagerly watching them trying to find it.

Like contemporary Margaret Meads, these scholars have gathered data from dating sites like Match.com, OkCupid and Yahoo! Personals to study attraction, trust, deception — even the role of race and politics in prospective romance.

They have observed, for instance, that many daters would rather admit to being fat than liberal or conservative, that white people are reluctant to date outside their race and that there are ways to detect liars. Such findings spring from attempts to answer a broader question that has bedeviled humanity since Adam and Eve: how and why do people fall in love?

“There is relatively little data on dating, and most of what was out there in the literature about mate selection and relationship formation is based on U.S. Census data,” said Gerald A. Mendelsohn, a professor in the psychology department at the University of California, Berkeley.