Readily available food in places packed with people may be the reason
A new study published in Communications Biology shows that urbanization is causing many mammal species to grow bigger, possibly because of readily available food in places packed with people.
The U.S. National Science Foundation-funded finding runs counter to scientists' hypothesis that cities would trigger mammals to get smaller over time. Buildings and roads trap and re-emit a greater degree of heat than green landscapes, causing cities to have higher temperatures than their surroundings, a phenomenon known as the "urban heat island" effect. Animals in warmer climates tend to be smaller than the same species in colder environments, a biological principle called Bergmann's Rule.