The friendship between dogs and humans finds a scientific basis that explains its origin

It is said a lot that it is man's best friend, but not so much that it is the oldest. Dogs were the first domesticated animal in history. Both species sewed their evolutionary destinies about 15,000 years ago, establishing a symbiotic relationship with few analogues in the animal world. A rarity. Archaeologists and zoologists proposed decades ago that this relationship was born of utility but that, over the years, a love and understanding arose that science is now trying to measure. Different studies have analyzed in recent years how this joint evolution affected dogs and humans. In the last 20 years, scientific literature on this topic has only increased. And the conventional one, too. It is estimated that There are more than 70,000 books about dogs on Amazon: one more sign that this prehistoric friendship reaches the present in full form.

Onyoo Yoo has a beautiful four-year-old poodle. She is called Scentbut at home they call him Ring. Before there were others: Yoo has spent his entire life surrounded by dogs and knows from his own experience that these animals can bring joy or comfort, but he does not fully understand the mechanisms that make it possible. Last year, Yoo brought her dog to work to find out. She asked 30 volunteers to pet her, give her treats, walk her and play with her. Meanwhile, Yoo, who is a researcher at Konkuk University in South Korea, analyzed her brain activity.

“Our research found that participants' alpha band brain waves [relacionada con la relajación] They increased while playing and walking with my dog. While beta band brain waves [que se asocian a la concentración] They did it while grooming her, massaging her or playing with her,” explains Yoo. The study, recently published in the scientific journal PLOS One, confirms something that many people feel: spending time with dogs is enormously pleasant. But it does so in a detailed way, “providing valuable information to elucidate the therapeutic effects and underlying mechanisms of animal-assisted interventions,” explains Yoo.

Owning a pet is known to help reduce stress levels, encourage positive emotions, and reduce the risks of cardiovascular disease. “However, research on the brain activity produced by human-animal interaction is incipient and insufficient,” says Yoo. It may be because, to understand it, you not only have to rely on neurology and psychology. We have to use paleobiology and look back.

Starting a friendship is not always easy, and the one forged between men and dogs did not arise by petting a wolf and throwing a ball at it. Domestication was multifactorial and happened in fits and starts. An ambitious study published in Science In 2020 he tried to trace this process by sequencing 27 genomes of ancient dogs. Analyzing them, the authors discovered that the dogs probably emerged from a now extinct wolf population. They also distinguished at least five different canine populations, drawing a complex ancestral history. Different types of dogs expanded with the many other human groups, linking their destiny (and their eventual disappearance) to the survival of the clan with which they had been associated.

Aritza Villaluenga, researcher at the University of the Basque Country UPV/EHU and co-author of the study, points out that the first (although disputed) evidence of coexistence between men and wolves dates back to 25,000 years ago: “Probably, it was not a conscious domestication, They did not know what they were doing, they did not conceive what the result was going to be. They simply had animals that helped them hunt.” We must take a time jump of 10,000 years until the first dogs appear on a sustained basis in history. “And here, yes, we can talk about dogs because genetically they are different from wolves that live in the same area at the same time. There are physical and genetic changes,” explains Villaluenga.

Allies for hunting

At that time, coexistence was symbiotic. “The association was good for the dogs and the humans. The dogs pushed herds of animals towards where the human hunters were, hiding,” explains the expert. The former had much more ability to run and the latter to devise strategies. They formed a good team when hunting and, once the game was collected, they both shared the loot. This made it very important, from the beginning of the relationship, that both species understood each other, that they could read each other.

An experiment with wolves, carried out by researchers from the University of Stockholm (Sweden), discovered that some specimens are capable of understanding human instructions and understanding their playful intentions. It was proven with something as trivial as throwing them a ball and asking them to bring it back. This action seems simple because it is everyday, because many do it daily with their pets. But it contains great cognitive complexity, it demonstrates in a few seconds the ability to understand two species that has been forged over millennia. The study suggested that this ability, present in some very sociable specimens, could have led to their domestication. Associating with humans was, from all points of view, an evolutionary success. It is estimated that currently, for every wolf, there are 3,000 dogs.

Some 5,000 generations after that prehistoric union, today's dogs are capable of understanding many more commands, gestures and words from humans. Mariana Boros, a neuroethologist at Loránd University in Budapest (Hungary), knows this well, and has just published a study that analyzes how dogs can understand words. “The most important ability that this animal has is to understand human communication. They are exceptional,” explains the expert in a video call.

Boros and his team wanted to verify that this understanding was due to vocalization and not context. So they locked a dog in a room, announced to him that they were going to give him an object, say a ball, and then offered him another, for example, a stick. “We thought that if the dog understood what the word meant, he would have an expectation of what he would see next. And the violation of that expectation would be visible in the electroencephalogram,” analyzes Boros. And, indeed, it was. With this data, the team can ensure that the dogs understand the meaning of the word. “In fact, the understanding mechanisms are very similar to what we see in humans,” adds Boros.

Love beyond understanding

The majority of scientific literature concludes that dogs have a special bond with humans for this reason. They understand us and communicate with us better than any other animal. Psychologist Clive Wynne, from the University of Arizona (USA), disagrees. in his book Dog is Love (The dog is love, is not published in Spanish) argues that what happens is that dogs have a unique capacity for interspecies love. If you raise a dog with sheep, goats or cats (even tigers or lions) he will end up hanging out with them and becoming fond of them, he explains, giving examples. Something similar would have happened with huma
ns. Wyne's idea is backed by science. In 2015, Japanese scientists showed that the more people looked into their dogs' eyes, the more their production of oxytocin, the fundamental chemical ingredient for affection, increased. It's not that they understand the humans they live with. It's just that they love them.

In any case, understanding is not the only aspect in which dogs have evolved to adapt to our tastes. Also, different studies point out, they have become more adorable and expressive. Charles Darwin was the first to realize that domestic animals—such as cats, dogs, and rabbits—share certain physical traits. They tend to have droopier ears and curlier tails than their wild ancestors. Their teeth are smaller, and they have white spots on their fur. This phenomenon is known as domestication syndrome.

The most eloquent example of this process occurred on a Soviet fox farm in the 1950s. Geneticist Dimitri K. Belyaev wanted to create a population of domestic foxes by selecting and crossing the tamest specimens. The results were analyzed in a scientific study in 2009. By the fourth generation, the foxes were licking the scientists and wagging their tails. Their descendants, even more domesticated, were capable of understanding human signals and responding to gestures or glances. “They developed not only internal traits such as acceptance of human closeness. Physically, they became more puppy-like, cuter. They changed to be more adorable to the human eye and it is presumed that the same thing happened to dogs,” explains Boros.

The difference is that this happened artificially and forcibly, in just 50 years, and the domestication of the wolf into a dog was natural and is assumed to be much longer. This process was not born from the whim of man, as Villaluenga explained. Some Stone Age wolves showed a natural inclination to befriend those strange apes that roamed the world. They understood each other not only when hunting, but also when playing or giving each other affection. Looking at each other, they both felt strangely good. These wolves came closer and closer to humans and mixed with other wolves that also roamed the human settlements. They decided to stay close, and it turned out to be forever. According to this interpretation, held by many specialists, the dog was not domesticated, but rather some wolves domesticated themselves and ended up becoming dogs. They chose us, at least as much as we chose them.

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