Until recently, scientists assumed humans were the only species in which females went through menopause, and lived a substantial part of their lives after they were no longer able to reproduce. And they had no idea why that happens, and why evolution wouldn’t push females to keep reproducing right up to the end of their lives. But after a close look at some whale poop, and a deep dive into chimp life, we find several new ways of thinking about menopause and the real purpose of this all too often overlooked second act of life. Special than...