What's the point of kissing? What biological function can a make-out session have? Or is it an evolutionary function? These are questions that are unlikely to cross your mind while watching Burt Lancaster and Deborah Kerr on the beach in that iconic scene from From there to eternity. But this is the question that some Oxford scientists asked themselves, leading them to investigate the kissing history of some animal species, especially primates. Because humans aren't the only ones who kiss: ants, birds, and polar bears do it too, to name a few. We're talking about kissing on the mouth, an action to which we attribute a romantic component that science seems to have trouble understanding, since—according to the new study—this action "doesn't appear to aid survival or reproduction in any obvious way, while the potential costs of transferring a disease are high." The very definition these Oxford scientists use strips away all the romanticism: kissing is "non-aggressive interactions involving directed, intraspecific oral-oral contact with some movement of the lips/mouthparts and no transfer of food."

Humans are by no means the only animals that practice sex just for pleasure. Nor are those of us who engage in it with individuals of the opposite sex as well as the same. In fact, at least 1,500 animal species have been documented with homosexual behavior. And in some, such as giraffes, males copulate primarily with other males. Others, like albatrosses or penguins, have stable homosexual partners for a significant part of their lives.

That life is full of coincidences and that it's about knowing how to seize them is something Tomàs Marquès Bonet (Barcelona, ​​1975), one of the world's leading experts in primate genomics and evolution, knows well. Although he wanted to dedicate himself to studying bats and Pyrenean frogs, he ended up at IBM performing banking transactions and learning to program. A few years later, life presented him with an opportunity to return to science, which he seized by writing a computational thesis at Pompeu Fabra University (UPF) comparing humans and chimpanzees. And so, it all began again. Since then, Marquès, a professor at UPF and ICREA researcher, and head of the comparative genomics group at the Institute of Evolutionary Biology (IBE UPF-CSIC), has dedicated himself to the molecular study of primates to learn about humans as a species. He argues that the genomes of our closest evolutionary relatives are key to understanding human biology. Also to combat the illegal trafficking of these animals and help their conservation.