Geckos are able to recognize their own scent

Reptiles have historically been seen as unsociable, primitive and impassive animals. But recent research has revealed that, at the very least, Tokay geckos – a species of lizard native to Asia – are a little more gregarious and intelligent than previously thought.

On a to study experimentally, a team of researchers from the University of Bern (Switzerland) shows that geckos —whose scientific name is Gekko gecko— can use their tongue to distinguish their own smell from that of other members of their species. Furthermore, the findings revealed that these types of reptiles are capable of social communication, which means they are more intelligent than previously thought.

Lizards and snakes move their tongues to absorb chemicals from the air and from the surface. “We tested the ability of adult Tokay geckos to distinguish between the chemicals (from skin and faeces) that they themselves generate, as well as those of other specimens of the same sex, and we found that they are as interested in their own odors as they are in hair. of other congeners”, explains the main author of the study, Birgit Szabo, to SINC.

We presented these reptiles with various olfactory stimuli and found that they are interested in their own odors and those of their conspecifics.

Birgit Szabo

During the experiment, the analyzed specimens were tried with other odors to rule out any novelty that could influence their reactions. “We recorded the number of tongue movements directed both towards an olfactory stimulus and towards the ground to see how they responded to different odors”, describes the researcher.

To check the answers, the team presented the geckos with different smells on cotton swabs: they were stimuli with smells of members of their species and other control smells, such as water or mint. The Swiss scientist points out that, given this, the evaluated specimens “reacted with two types of behavior: on the one hand, showing their tongue to the smell of the cotton swab and, on the other hand, to the surrounding area”.

The research team interpreted this response as “a sign that geckos first perceive a strange odor and then compare it to their own”. In this sense, the author of the study clarifies that these reptiles “have to compare more often when they perceive the smell of another gecko than when they catch their own, which shows that they know their own smell”.

According to the study, geckos compare the smell of another member of their species more often than their own, indicating that they recognize it.

In this case, as Szabo points out, the analyzed specimens were more interested in the odors exhaled by themselves and other animals of their species than by the controls with which they were experimented (water and mint).

According to the researcher, “the most relevant thing is that the geckos showed more tongue movements towards the ground —which is interpreted as being able to perceive their own smell— to detect the chemical substances of their peers than for their own”.

Pheromones for social communication

Self-recognition is the ability to detect stimuli that come from oneself. People, and also some animals, can identify visually when we look in the mirror. However, not all animals depend on the sense of sight.

Geckos, like other lizards and snakes, use their tongues to detect chemicals from other individuals called pheromones. For example, when climbing a wall, geckos stop every now and then to click their tongues. This allows them to identify potential partners or rivals.

Geckos, like other lizards and snakes, use their tongues to perceive the pheromones of other individuals.

The study, published in the journal Animal Cognition, concludes that geckos are not only able to recognize their own scent, but are also able to distinguish between their own chemicals and those emanating from other members of their species.

And the fact that the animals in the experiment were more interested in the skin chemicals of other geckos than their own shows that these reptiles use pheromones for social communication.

In fact, the team was also able to show that geckos detect and use the odors of their droppings to distinguish themselves from others. So they also deposit pheromones in their droppings, for example to mark their territory. That’s because, like many mammals, these reptiles have preferred areas to defecate, so they can communicate their presence.

One of the most intriguing results for this scientist was “confirming the prediction that they would compare their own odor with what was presented to them”. Now, as he explains, “we can take advantage of these results to understand that they recognize each other through chemical substances”.

Smarter than I thought

Szabo also recalls that “lizards and reptiles are often considered antisocial primitive animals”. However, he states, “we must recognize that they are more sociable and intelligent than we thought”.

In this regard, the researcher argues that, like other groups of animals, reptiles and, above all, lizards, exhibit a wide range of social behaviors: “from tolerance or the formation of monogamous couples to parental care or family groups long-term stable.

Reptiles, and especially lizards, are as well suited as any other animal group for studying the evolution of sociality.

Birgit Szabo

In this context, he emphasizes that they are as suitable as any other animal group for studying the evolution of sociality. “We could even argue that the expression of sociability in reptiles is more like group life in the early stages of social evolution.”

Consequently, Szabo and his team believe that new insights can be gained about the adaptations that likely evolved during these early stages.

“Reptiles, and especially geckos, are well suited to investigating fundamental questions about the evolution of sociability. Within geckos we can find a wide variety of social structures and habitats”, reinforces Eva Ringler, professor at the University of Bern and co-author of the study.

Finally, the researcher states that “this allows exploring the interrelationships of cognition, communication and social life within a small taxonomic group and making comparisons between these and other groups of animals, such as mammals and birds”.

Szabo, B. et al. “Lucks differentiate themselves from others by using chemicals from their skin and faeces: evidence for self-recognition?”. Animal Cognition (2023).

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