Biologists are only just beginning to tease out answers, since a few decades ago, this research wasn’t possible. Seychelles warblers were among the most endangered animals on the planet, according to Richardson. At one point, Cousin Island was down to just 29 individuals. With so few breeding pairs, there was no surplus population to fill the subordinate roles, and the species’ cooperative breeding habits was obscured. But conservation has brought the warblers, and all their unique behaviors, back from the brink. Now, we know as much about the fliers—or perhaps more—than just about any other species on Earth. And they may just help us better understand ourselves.