Jane Barlow Schwartz is obsessed with one question: why did her best friend Martha stop being her best friend? The two girls, distant cousins, had shared idyllic childhood summers in the New England seaside town named for their family's founding fathers. Martha was not just Jane's friend, but her soul mate, her confidante. Then, somewhere along the line, the friendship ended. What went wrong? Was it the family feud, which their parents spoke of only in hushed tones? What did Jane's dotty great-aunt reveal to Martha on her deathbed? Did Jane do something unforgivable?

When the cousins are reunited unexpectedly on a tour of the Galápagos Islands, they meet Darwin head-on. In the pristine Galápagos waters, amid blue-footed boobies and red-lipped batfish, Jane traces back through her Yankee-Cuban-Jewish ancestry to try to pinpoint the "splitting event," the moment when Martha was no longer the Martha she knew.

Bearing Schine's rich wit and playful imagination, "The Evolution of Jane" sparkles with keenly comic observations on the species known as humans. Above all, it is a warm-hearted tribute to that unique adaptation of girlhood, the selection of a vert best friend.