In 2006, Harvard sociologists struck a mother lode of social-science data, offering a new way to answer big questions about how race and cultural tastes affect relationships.
The source: some 1,700 Facebook profiles, downloaded from an entire class of students at an "anonymous" university, that could reveal how friendships and interests evolve over time.
It was the kind of collection that hundreds of scholars would find interesting. And in 2008, the Harvard team began to realize that potential by publicly releasing part of its archive.
But today the data-sharing venture has collapsed. The Facebook archive is more like plutonium than gold--its contents yanked offline, its future release uncertain, its creators scolded by some scholars for downloading the profiles without students' knowledge and for failing to protect their privacy. Those students have been identified as Harvard College's Class of 2009.