In search of younger-looking skin, humans turn to all manner of bizarre treatments, from fish jizz to menstrual blood.

Scientists discovered that river otter droppings contain large numbers of parasites that infect the animals’ prey, indicating that otters may play a significant role in shaping local food webs.

Raven La Fae, a 32-year-old artist in Calgary, Canada, has always been able to predict their menstrual periods almost to the day; it arrived every 28 days and lasted for five. But after contracting ...