(I know, I know, I couldn’t help myself)
Last week’s post ended with a couple remaining questions about how dogs understand human social cues:
1. Was the evolution of this skill due to humans specifically breeding wolves that understood human social cues, or was it due to humans breeding wolves based on a more general trait, like behaving friendly towards humans (or, on the other hand, NOT breeding wolves that showed aggression towards humans)?
2. How would you even test the domestication hypothesis, besides spending thousands of years selectively breeding wolves (again)?
One fascinating study that addresses both of these questions is the Russian Fox Experiment. The experiment began in 1959, when Soviet scientist Dmitri Belyaev started breeding silver foxes for tameness. He would only breed those foxes that showed the most friendliness and least aggression towards humans. After generations of this selective breeding, the foxes behaved very much like dogs: they were eager to be around humans, wagged their tails, and even evolved floppy, dog-like ears! This experiment is essentially the domestication of the silver fox, and likely parallels the domestication of the dog.
(For more information about this experiment, including some great pictures and videos, check out this fantastic post on The Thoughtful Animal, an animal cognition blog on Scientific American’s website.) (Edited: That post’s author, Jason Goldman, wrote another version of that post, which goes into more detail about the history of the experiment.)
Fortunately for our purposes, the Russian Fox Experiment is still going strong. Since we know exactly which traits the domesticated silver foxes are bred for, testing them on the food-finding task could tell us whether selectively breeding for tameness alone is sufficient to develop the skill of understanding human social cues.
When researchers tested domesticated silver fox kits and adults, they found that the foxes were just as good as dogs on the food-finding task. Undomesticated “control” silver foxes, which had not been selectively bred for any trait, performed worse on the task than the domesticated silver foxes and the dogs. These findings indicate that the domesticated silver foxes developed the ability to understand human social cues through domestication, which is the same process we theorize for dogs (the domestication hypothesis).
Furthermore, the results suggest that selectively breeding for tameness alone is sufficient for developing the ability to understand human social cues. In other words, we didn’t need to specifically breed foxes or dogs for this specific trait — we could just breed them for the more general trait of tameness, and the trait of understanding human social cues was part of the package.
There is evidence, however, that this ability can be improved by more specific selective breeding. Researchers ran the food-finding task yet again, this time comparing the performance of working dogs (shepherds and huskies) and non-working dogs (basenjis and toy poodles). Working dogs have theoretically been bred to cooperate with humans, whereas non-working dogs have not. The working dogs did perform significantly better than the non-working dogs on the food-finding task, showing a greater ability to understand human social cues.
Together, the results of these studies suggest a mechanism for the evolution of the ability to understand human social cues in dogs: domestication by selectively breeding for tameness was sufficient to develop this ability, and additional selective breeding can improve this ability, for example in working dogs.
Thanks for sticking with me through this (longer-than-originally-planned) series of posts — hopefully it was interesting and gave you something to think about! Next week we’ll move on to another area of animal cognition.
I’ll leave you with this timely Op-Ed on LiveScience called “Does a Dog’s Breed Dictate Its Behavior?”.
Goldman, Jason. “Monday Pets: The Russian Fox Study.” The Thoughtful Animal. Scientific American, 14 June 2010. Web. 1 Oct. 2013.
Hare, Brian, et al. “Social cognitive evolution in captive foxes is a correlated by-product of experimental domestication.” Current Biology 15.3 (2005): 226-230.
Wobber, Victoria, et al. “Breed differences in domestic dogs'(Canis familiaris) comprehension of human communicative signals.” Interaction Studies 10.2 (2009): 206-224.