Recognition of one’s own reflection is considered an advanced ability, confirmed only in a small number of species, such as chimpanzees, orangutans and dolphins.
“Snakes exhibit many of the same cognitive and perceptual mechanisms as other animals. if we learn them right, if we ask the right questions and if we respect their biology and their view of the world,” says Burghardt. (Read: Discover fourteen animals that show unrivaled intelligence.)
In a study recently published in the journal BehaviorBurghardt and colleagues studied twenty-four garter snakes from the same litter in their Tennessee lab.
The snakes were reared individually from birth and fed either entirely on fish or entirely on worms, allowing their droppings to be chemically distinguished.
When they were four months old, the team individually exposed them to four different stimuli: their own dirty cage liner, a same-sex sibling who was on the same diet, a same-sex sibling’s dirty cage liner. who was on a different diet, and a clean cell liner.
During each experiment, the scientists measured the rhythm of the snake’s tongue and its movements in the cage.
The snakes extended their tongues more slowly when exposed to the dirty cage liner of another snake that was on the same diet than when exposed to their own dirty cage liner.
This behavior demonstrates that garters can recognize that their own chemical signals are different from those of others, even if other individuals come from the same litter and eat the same diet, Burghardt said.
About fifty years ago, American psychologist Gordon Gallup and his colleagues developed the mirror test to study the ability of animals to recognize their reflection, a test that is still used in many experimental studies.
Researchers place a marker on a part of the animal’s body that it can only see in its own reflection. If the animal looks in a mirror and then touches or examines the mark on its body, it passes the test. Humans have been good at this since childhood, and some great apes, such as chimpanzees, orangutans, or bonobos, also manage to recognize themselves. Only some non-primate animals, such as elephants and dolphins, may also qualify.
Gallup and colleagues, however, are skeptical of the evidence offered by the mirror test of self-recognition ability in species other than humans or apes. They have also criticized non-visual self-knowledge studies, such as those using odors or other chemical cues, that claim to be as effective as mirror tests.
That’s why James Anderson of Kyoto University, a collaborator at Gallup, argues that while Burghardt’s snakes show the ability to recognize themselves chemically, this ability is not comparable to the ability of humans or monkeys to recognize themselves in a mirror.
“Many researchers overlook the spontaneity with which great apes [et nous-mêmes] let’s use mirrors to keep track of our appearance or even change it or watch it from different angles,” he wrote in an email. “There is no convincing evidence that the so-called “chemical mirror” can be used in this way. »
Burghardt replies: “I am not saying that these snakes are endowed with self-awareness. But they seem to be aware that they are a different entity from another organism. »
The scientific community is also divided on the real significance of the fact that an animal recognizes itself in a mirror in terms of cognition. Gallup and Anderson argue that taking the test demonstrates the ability to demonstrate self-awareness and perhaps even awareness of the uniqueness of others.