We humans excel in recognizing between many other individuals.

We humans excel in recognizing between many other individuals. We use many clues, like face, voice, gestures, and even smell, depending on situation, to guess whether we know the other person and precisely who he or she is. For us, recognition of tens and hundreds of individuals is an easy task. We humans evolved as very social species. Keeping the track about who is who in the group and how they behaved to us is a crucial skill for humans. Our brains possess special skills for recognition of other individuals. Our faces evolved to stress differences between individuals to make the recognition easier for our brains.

Such skills are not common to many other animals.

We do these cognitive tasks so automatically that we do not realize that such skills are not common to many other animals. Some species may only distinguish individuals in two categories – familiar or unfamiliar. Many animal parents do not distinguish different individuals between their offspring despite the fact that there are clear differences between them. Such failure of recognition shows that mechanisms allowing recognition may be costly for animals. And, if individuals “do want” to be recognized, they must stop relying on a fact that there is always some individual variation. They need to get traits which will make them more different and recognizable from the other individuals – the true identity signal. Our faces are an example of such identity signal.

Is there selection to sound different in animal kingdom?

One does not need to be a scientist to see that individuals of many other species are individually distinct and it is possible to distinguish between them. However, to decide whether the species poses a true identity signal is a tricky thing. Even more tricky, is to find out how the identity signalling gradually evolved. With any behaviour, there is a problem that, unlike bones, behavior does not fossilize. Many times, the only way how to learn about the evolution of behaviour, such as identity signalling in case of this project, is to use phylogenetic comparative method. We need to look at the extant species and assess how much identity information is there in their signals. Subsequently, it is possible to infer what evolutionary processes lead to current state, which were the transitional steps during the process and which factors (like, for example, number of individuals the animal regularly encounters) affect whether a species has high or low identity information in its signals.

There is enough studies that assessed individual variation in vocalizations. It is the right time to conduct such comparative analysis. This will be the ultimate aim of this project. However, before that it is neccessary to develop statistical methods that will allow comparison of results from those many different studies.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665778 within the grant scheme Polonez 1 administrated by the National Science Centre, Poland (UMO-2015/19/P/NZ8/02507).

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