A new study finds that dogs’ brains have shrunk since domestication. That’s likely because life with humans demands less brainpower than life in the wild. Humans are largely responsible for the change. The finding comes from a team at the Institute of Ecology and Botany at the Center for Ecological Research in Hungary, led by László Zsolt Garamszegi.
Dogs are canids that were domesticated at least 15,000 years ago. There are now more than 400 dog breeds worldwide. Overall, relative brain size in modern breeds is smaller than in their wild ancestor, the gray wolf. Veterinarians and other experts say dogs’ brains have been shrinking over centuries of domestication. Domesticated dogs faced fewer demands for finding food, escaping predators, or securing mates than their wild counterparts. With those reduced cognitive demands, brain size gradually decreased — a trend reported by the Daily Mail. The paper adds, “The phenomenon results from a decreased need for metabolically costly brain tissue in a domesticated environment.”
How the Research Was Conducted
The team set out to check whether domestic dogs have smaller brains relative to body size than wild canids. They analyzed brain and body sizes for 25 canid species, including the domestic dog (Canis familiaris), the gray wolf (Canis lupus), and the raccoon dog (Nyctereutes procyonoides). They found domestic dogs’ brains are significantly smaller relative to body size than those of their wild ancestor, the gray wolf. Still, the domestic dog has a relatively large brain compared with some other species. A notable exception was the raccoon dog, which has an unusually small brain for its body. The team suggested this may be because it is the only canid that hibernates.
Hibernation involves long stretches of low metabolic activity and food scarcity, which likely contributes to smaller brains. The paper says, “Extended periods of food scarcity, such as during hibernation, hinder brain development due to permanently high energy demands.” The authors conclude that domestication is linked to decreased brain size, and hibernation may also drive reductions in wild canids. The study appears in Biology Letters.
