New research has shown that despiteIt is widely believed that relative brain size in mammals is not only related to intelligence, but also due to various evolutionary factors that influence body size, including adaptations caused by mass extinction and climate change. The international study - the largest of its kind - involved a team of 22 scientists who examined 1,400 living and extinct mammalian species. This groundbreaking work has brought together a unique chronology of brain evolution and body size over the past 150 million years, showing how “big-brained” species have reached their extreme proportions in a variety of ways. For example, great apes have a wide range of body sizes, but have shown a general tendency to increase in both brain and body size. In comparison, ancestral hominins that represent the human line showed a relative decrease in body size and an increase in brain size compared to great apes. The findings also showed that relative brain size may have nothing to do with intelligence at all.
Does size matter?
So, scientists have finally refuted the long-standing dogma aboutthat the relative size of the brain can be equated with intelligence. According to the authors of the paper published in the journal Science Advances, sometimes a relatively large brain can be the end result of a gradual decrease in body size. This allows the body to adapt to a new habitat or mode of movement. In other words, nothing at all to do with intelligence.
Comparison of brain and body sizes preserved inthe fossil record allowed the team to gain insight into the historical changes taking place against the changing ecological background. As a result of the blow that killed the dinosaurs that ended the Cretaceous Period, a group of tiny mammals such as rats, shrews and bats underwent significant changes in their brain and body scale - as they got larger, their brains changed too.
Likewise, with the cooling of the climate at the endPaleogene 30 million years later, mammals, including seals, bears and our own ancestors, took advantage of empty niches to fuel and build body weight and brain size.
“The big surprise was that mostThe differences in the relative brain size of mammals living today can be explained by the changes that their ancestral lines underwent after these catastrophic events, ”the researchers said in an interview with Sciencealert.
All of this, however, does not mean that generalizations about larger brains and increased cognitive abilities are complete nonsense. When it comes to the intelligence of other animals, the size Is only one element that matters.
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Brain Size and Intelligence
Professor Anjali Goswami, Academic SupervisorNatural History Museum, London, notes that the results of the new study illustrate the danger of our own biases in interpreting the natural world. He cites the example of dolphins, which have developed relatively large brains, not by increasing brain size, but rather by decreasing both brain size and body size. The complexity of these patterns has led researchers to completely redefine what drives the evolution of brain size. “Our research shows that there are many different ways in which a species develops a large brain,” the study authors write.
Another surprising conclusion of the new workis that most of the changes in brain size appear to have occurred after two catastrophic events in Earth's history. Following the mass extinction at the end of the Cretaceous 66 million years ago, researchers noticed a dramatic change in the relative brain and body size in lines like rodents, bats, and carnivores as these animals filled the empty niches left by extinct dinosaurs.
About 30 million years after coolingThe climate in the Late Paleogene led to deeper changes when seals, bears, whales and primates underwent evolutionary changes in their brains and body size. Elephants and great apes developed their extreme proportions following this climate change event.
See also: What did the brain of dinosaurs look like? The most complete reconstruction has been created
In addition to demonstrating that the size of the brain ishas not followed a stable evolutionary trajectory in relation to body size, research also shows that relatively large brains, long considered an indicator of animal intelligence, may be the result of gradual reduction in body size according to the new habitat, climate or mode of travel. In other words, relative brain size may have nothing to do with intelligence at all.
“Our work emphasizes that resizingthe body is a key factor in changing the relative size of the brain, and opens up new possibilities for thinking about the complex ways of brain evolution, "- write the authors of the scientific work.