Who’s a good doggy?
Traditionally, self-consciousness is tested using the “mirror test” — if an animal uses its own reflection to examine or touch a red mark that been applied to its own body without its knowledge, either by distraction or under anesthesia, scientists can confirm that they possess a sense of self.
Great apes, dolphins, orcas, rhesus macaques, Eurasian magpies, some ants, and a single Asian elephant have all passed the self-recognition test, and now dogs can be added to the list. “I believed that because dogs are much less sensitive to visual stimuli with respect to what, for example, humans and many apes are, it is likely that the failure of this and of other species in the mirror test is mainly due to the sensory modality chosen by the investigator to test the self-awareness and not, necessarily, to the absence of this latter,” said evolutionary biologist Roberto Cazzolla Gatti from Tomsk State University in Russia.
Dogs, in particular, show no interest in looking at their reflection in the mirror, however, they will usually sniff or even urinate around it. Dogs and wolves show high levels of cognitive complexity, but since both have failed the mirror test in the past, Gatti decided to try a new approach: the Sniff Test of Self-Recognition (STSR).
There have been attempts to verify this idea before, such as the “yellow snow test” by Marc Bekoff, renowned animal behavior expert, who measured how long his dog, Jethro, was sniffing his own urine scent and those of other dogs over a five-year period. Not surprisingly, Jethro paid a lot less attention to his own urine, so Bekoff concluded that his dog had a sense of self — being able to recognize his own scent. However, his study only supplied observational evidence.
The STSR experiment involved collecting urine samples from four stray dogs and exposing them to the scents four times a year — at the beginning of each season. “I placed within a fence five urine samples containing the scent of each of the four dogs and a ‘blank sample’, filled only with cotton wool odorless,” Gatti said. “The containers were then opened and each dog was individually introduced to the inside of the cage and allowed to freely move for 5 minutes. The time is taken by each dog to sniff each sample was recorded.”
Just like Jethro, each dog spent a lot more time smelling other dogs’ urine samples than their own, supporting the idea that they know their own scent. Interestingly, there was a correlation between the age of the dogs and the time spent sniffing the urine samples, suggesting that self-awareness increases with age, just as with humans.
The next step to identifying self-recognition in other species, now that we know using mirrors is not the only way, might be to test using chemical or auditory perception. Maybe all species are self-aware, we just weren’t testing them correctly.