Deena Emera was mesmerized by the images on the screen. “They were beautiful,” she says of the slides she saw in December—each a microscopic closeup of a bowhead whale’s ovary. The images were marvelously crisp and showed the mottled outer layer of the organs. Bowhead whales are considered the longest-living mammals on earth. They can live for more than 200 years, and females can reproduce well after their 100th birthdays. Emera, an evolutionary biologist, has long wondered: “What is different