By now it’s common knowledge that human beings are gaining weight in many countries around the world. Unsurprisingly, pets are getting fatter as well, often because their owners aren’t paying enough attention to their health. What’s not so well-known is that other animals are putting on the pounds. According to a 2010 study from the University of Alabama-Birmingham that examined animals from eight different species living with or near humans, all have seen an increase in body weight over a period of decades. Notably, chimpanzees living in captivity experienced an average weight gain of 35 percent per decade, and wild rats in Baltimore and rural Maryland are, on average, five pounds heavier than they were 60 years ago.
What’s the Big Idea?
Scientists are pretty clear on many of the causes of obesity among humans and pets, but the picture becomes murkier when dealing with captive animals, whose diets are rigidly controlled, and their wild cousins. The study names a number of possible environmental contributors, such as the presence of endocrine disruptors and certain obesity-triggering viruses. Captive animals and even rats may also be affected by living in climate-controlled conditions where, just like humans, they no longer have to burn calories to stay warm or cool.