Dogs' brains are exceptionally normal
For thousands of years, dogs have allowed humans to think for them. This eases the selection pressure. And now their brain is much smaller than that of a wolf. Coincidence?
Since wolves have settled in with us humans, they have had to take care of much less themselves than their wild ancestors: Feeding, choosing a mate, defence against danger - all this is usually taken care of. As a result, their brains are said to have gradually shrunk. The selection pressure that required their wolfish relatives to always be on guard diminished - and with it the need for an energetically costly brain.
Something similar has also been observed in other pets. However, László Zsolt Garamszegi from the Centre for Environmental Research in Vácrátót, Hungary, and Niclas Kolm from Stockholm University doubt the accuracy of this hypothesis. In a new publication in the scientific journal "Biology Letters", they write: If domestication were really as strong a factor as claimed, the domestic dog should clearly stand out in the brain size statistics. But it does not.
In fact, its brain is noticeably smaller than that of a modern-day wolf (more than 24 per cent according to the authors of the study). However, calculations showed that the brain volume of the domestic dog is roughly what you would expect from an animal of its body size if, like the two researchers, you compare it with 25 other members of the dog family (Canidae).
In contrast, they recognise a brain that really stands out in the tanuki. It is the only member of the dog family that hibernates. According to the scientists, the long period of rest, during which it has to live solely from its stored reserves, is more likely to have an evolutionary influence on brain size than domestication.
The brain volume of today's domestic dogs could have been determined more by the characteristics favoured by the first breeders thousands of years ago. Today's wolves may also not be a good example of the animals from whose ranks the first dogs descended.
With hundreds of dog breeds, the body and brain size of today's animals varies greatly. Garamszegi and Kolm therefore used the corresponding values of eleven original dog breeds, which are most likely to have the favoured characteristics of the first domesticated dogs. These breeds include sled dogs from Greenland and Alaska, the Japanese Akita Inu, the Chinese Shar-Pei and some greyhounds.
Spectrum of Science
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