No way simple reptiles: Geckos have a form of self-awareness, the results of an experimental study suggest. They can distinguish their own smell from that of their conspecifics, as can be seen from behavioral patterns in tongue-in-cheek smell tests. The possible self-recognition in turn provides evidence that intelligence and social communication skills have been underestimated in these animals, say the scientists.
“That’s me!” The ability of humans and some animal species to recognize themselves is made clear by the so-called mirror test: After initial irritation, they begin to understand that they are not seeing a fellow species, but an image of themselves. The point test is proof of this: Malt If you put a point in the face of apes, they marvel at what they see in the mirror and touch the spot themselves. Similar behaviors have now also been observed in other animals.
However, some animal species – including those that are considered particularly clever – do not pass the mirror test. One possible explanation is that other senses play a more important role than sight in perceiving identities. For example, dogs also fail the mirror test. However, certain behaviors clearly show that they can recognize their own scent. A point test is not possible, but at least it shows that dogs have a form of self-awareness. This is probably the case for other species as well.
On the trail of olfactory self-recognition
Birgit Szabo and Eva Ringler from the University of Bern have now investigated whether signs of olfactory self-recognition can also be detected in geckos. Because the sense of smell also plays an important role in the life of many reptiles. They are known to use their tongues to detect signaling chemicals called pheromones from other individuals. With geckos, too, it is obvious that they take in important information when they “tongue” – such as about possible sex partners. But can geckos recognize their own scent?
In order to investigate this question, the two researchers carried out experiments with geckos of the Gekko gecko species kept in terrariums. They presented the reptiles with various smell samples on cotton swabs. These were smears that had previously been taken from the surface of the test animal’s skin or from conspecifics of the same sex, as well as control odors. When the different cotton swabs were presented, the behavior of the respective test animal was recorded and analyzed.
Smarter and more social than you think?
As Szabo and Ringler explain, the geckos showed two aspects with their “tongue-nose sniffing”: On the one hand, they stretched out their tongue in the direction of the smell, but also repeatedly in other directions in their immediate vicinity. In doing so, the researchers have now identified peculiarities in the different odor samples: tongues were tongued much more frequently at the smell of conspecifics than at one’s own. They suspect that the geckos first perceive the smell on the swab and then compare it to their own smell in the immediate vicinity. “The geckos did this more often when they encountered another gecko’s scent, as opposed to their own. This suggests that they know their own smell,” explains Szabo.
Further experiments showed that the animals react similarly to the smell of their own or other people’s faeces. In other words, they recognize their own shops and use this ability to distinguish them from the droppings of other geckos in their habitat. This fits in with the well-known behavior that the small reptiles, like many mammals, also use certain droppings deposits. Apparently, they also use this to inform their conspecifics of their presence.
The results cannot be equated with mirror tests and further investigations are needed to further explore the ability to recognize oneself. But at least complex cognitive performance is already emerging in these often underestimated animals, say the researchers. “Lizards, and reptiles in general, are viewed as antisocial proto-animals. We need to recognize that reptiles are more social and intelligent than previously thought,” Szabo said.
Source: University of Bern, specialist article: Animal Cognition, doi: 10.1007/s10071-023-01751-8