America is suffering from an obesity epidemic—and not just among the humans. A new study of more than 20,000 animals shows that even family pets, wild critters that live close to humans, and research animals are getting fatter, Scientific American reports. The biostatistician who published the study looked at weight changes in eight different species including primates and rodents in research centers, pet cats and dogs, and urban rats. They're all packing on the pounds.
"Now, we don't know why these increases occurred, but it invites some very interesting speculation," he says. Unhealthy food and lack of exercise are blamed for the human problem, "but maybe there are other things that are important—because those things can't be acting on the marmosets, or the rats and mice in the National Toxicology Program." One theory is that it's something in the water, literally: maybe toxins that are messing up the endocrine system of humans and animals alike. Future studies may explore the possibility. (Read more obesity stories.)