Hunting as an evolutionary factor. Birds are getting smarter

People have always hunted animals. Before - in order to get their own food. Now in most cases of sports interest. One of the most attractive for hunting enthusiasts the object of pursuit are birds. Moreover, modern scientists believe that hunting may well be one of the factors of evolution, the influence of which leads to the appearance of more intelligent individuals with a larger brain size than their ancestors. The difference in size is not too great, but perhaps it plays a role in the survival of the birds.

Scientists have made their conclusions by studying the behavioral characteristics of the bird population in Denmark. The work is also interesting because it clearly demonstrates that the size of the brain is an important factor in the development of mental abilities.

According to John Marzlouff, a wildlife expert and raven cognitive expert, the new work "expands the boundaries of cognition and shows that the mind is a significant factor in nature, over which man is gradually taking over." Marzluff is a biologist at the University of Washington in Seattle, he has nothing to do with the recently published work of Danish specialists.
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The fact that fishing and hunting are important factors of modern evolution, no one argues. For example, due to the constant catch of the largest individuals of zander, the population of this species of fish living in the region of the Finnish archipelago has changed. The pike perch began to grow smaller. And not because the fishermen catch individuals of a large size, not allowing young individuals to develop. No, the catch rules are respected here. The problem is that the fishermen catch the largest individuals in the population, which results in the generation of offspring of genes of such large fish. It is interesting that puberty in this population of pike perch occurs earlier than decades ago.

Not only man is an evolutionary factor. For example, land predators like arctic foxes or polar bears also “force” their victims to become smarter from generation to generation. A recent study showed that sea ducks, where birds with large heads dominate the flock, can organize better protection than flocks where there are more small ducks with small heads. At the same time, scientists did not measure brain size, but made the assumption that the size of the head in this case is directly related to the size of the bird's brain.

Is this all true for hunter people and their flying victims? In order to find out, Anders Pape Møller, an evolutionary biologist from the University of Paris-South XI , decided to check the brain sizes of 3781 birds of 197 species that fell into the hands of taxidermists (animal stuffed animal expert) in Denmark from 1960 to 2015 year. Other species include pheasants, partridges, black grouses, magpies, and gray crows. According to Danish law, taxidermists must record the date and cause of death of any animal from which they are stuffed. Co-author of the study, Johannes Erritso, a taxidermist and ornithologist from the Birds Research Center in Christiansfield, Denmark, autopsied each bird. At the same time, he noted the mass of each specimen, as well as weighed the extracted brain. Scientists have also recorded the condition of the body of birds, and the age at which the bird died.

As it turned out, 299 or 7.8% of the studied birds from 3781 were shot down. Birds with a small brain (compared to the size of the whole body) were more likely to die from gunshot wounds than birds with a brain, the size of which was larger in relation to body size. It was also noted that the victims of hunters often became large birds (this is a convenient target) and males (in most cases they have brighter colors).

As it turned out, the probability that a hunter will shoot a bird with a brain large in relation to the size of the body is much less than the inverse probability. Experts noted almost 30-fold difference . The research results are published in the publication Biology Letters. This dependence can be traced regardless of the health of the bird, body weight, sex and belonging to a particular species. Hunters, according to the results of the study, involuntarily force the birds to evolve, destroying members of the population with a small brain. Representatives of the same species of bird with a larger brain, as claimed by Danish scientists, are smarter than other relatives, therefore they successfully avoid hunters and traps.

Scientists compared the size and other organs of birds - the heart, liver, lungs, and found that only the brain size of those birds that have been hunted for a long time has changed. “This means that hunting has a very specific effect on the brain of birds, and only on him,” says Moliere.



According to him, the hunters do not set themselves the task of finding and shooting the bird with a small head. Just birds with a smaller brain do not so successfully avoid hunters. “They have a longer reaction time. Between the time of the hunter’s discovery and the perception of danger, such birds take longer than their smarter relatives. ”

Now experts are testing their hypothesis by studying curlews and snipe, the hunt for which has been banned for five years in Denmark. Scientists want to compare the specimens of birds that in previous decades fell into the hands of taxidermists with modern representatives of these species.

The results of the study interested many other scientists, including Susan Healy from the University of St. Andrews. Healy conducted about 50 studies during her work, the purpose of which was to find out the connection between the brain size of animals and the behavioral characteristics of various representatives of the same animal species, including cunning, sexual preferences and propensity to migrate. Significant results in this work did not have .

The work of Danish scientists raises a few more questions. For example, is the evolution of birds that a person hunts long and irreversible in time? How will all this affect the hunt itself in the future? And how does this affect the relationship between natural predators and their prey - isn’t it becoming the first to go hunting the last? It is still difficult to answer all these questions, so we will have to wait for the results of new research.