Geckos can use their tongue to identify their own odour differentiating it from that of other members of their species

In a new experimental study, researchers from the University of Bern have shown that Geckos can use their tongue to differentiate their own odour from that of other members of their species. The findings show that geckos are able to communicate socially, meaning that they are more intelligent than was previously assumed.

Self-recognition is the ability to detect stimuli which come from oneself. We as people, and also some animals, can identify ourselves visually when we look in the mirror.

However, not all animals rely on their sense of sight, first and foremost. Geckos, and also other lizards and snakes, use their tongues to perceive chemicals, so-called pheromones, from other individuals.

For instance, when climbing a wall, geckos pause every so often to dart their tongues around. This enables them to detect potential partners or rivals.

But can geckos also detect their own odour and recognise themselves by smell?

In a recent study, researchers at the Institute of Ecology and Evolution of the University of Bern focused on whether Tokay geckos can detect skin chemicals that they themselves produce, and whether they can discriminate between these chemicals and those of other geckos of the same sex.

The experiments confirmed that geckos are capable of this. During the tests, the animals were more interested in the skin chemicals of other geckos than in their own. This shows that geckos use pheromones for social communication.

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two types of behaviour

During the experiment, the researchers presented the geckos with various odours on cotton swabs.

As well as their own odour, these were odours from other geckos, or control odours such as water and peppermint.

When they reacted, the geckos showed two types of behaviour: on one hand, they stuck out their tongues in the direction of the odour on the swab and, on the other hand, towards the surrounding area, their own home enclosure.

The researchers interpreted this behaviour as a sign that the geckos first perceive the odour on the swab, and then compare it with their own odour on the walls of the enclosure.

Birgit Szabo, lead author of the study from the Division of Behavioural Ecology at the University of Bern’s Institute of Ecology and Evolution, said: “The geckos have to compare more frequently when confronted with the odour of another gecko, compared to their own odour. This indicates that they know their own odour.”

In an experiment, the team was also able to show that geckos detect and use the odours of their faeces to distinguish themselves from others.

Geckos also deposit pheromones on their excrement, for instance, to mark their territory. This is because, just like many mammals, geckos have preferred areas for defecation so that they can communicate their presence.

evolution of society

The findings of the study show that geckos can communicate socially by using chemicals from their skin and excrement, and that they use these chemicals to distinguish themselves from other geckos.

Szabo said: “Lizards and reptiles are generally seen as unsocial primitive animals. We must recognise that reptiles are more social and intelligent than we thought.

Eva Ringler, professor and head of the Division of Behavioural Ecology at the University of Bern, added: “Reptiles, and especially geckos, are ideally suitable for investigating fundamental questions about the evolution of sociality.

“Within geckos, we can find a vast range of social structures and habitats. This allows us to investigate the inter-relationships of cognition, communication and social living within a small taxonomic group – and make comparisons between these and other, more distantly related groups of animals such as mammals and birds.”

The research is published in Animal Cognition.

Image: Objects of the study of the researchers of the University of Bern were Tokay geckos (Gekko gecko).

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