In the more than six million years since people and chimpanzees have separated from their common ancestors, human brains have quickly accumulated tissue that helps with decision -making and self -control. But the same regions are also most susceptible to dismantling in old age, such as a study 1 Mixture shrews compared to scans of human brains.

Earlier studies have shown that regions of the human brain that recently show tires, such as parts of the frontal lobe, as the first sign of aging 2 , a theory known as 'load in, first out'. The latest study shows that some of these regions that are later mature and most susceptible to aging were also developed in humans.

The results tend to "support the important hypothesis that our cortical expansion has paid its price for age -related dismantling," says Rogier Mars, neuroscientist at the University of Oxford, Great Britain. The results were published on August 28th in science advances

thought cards

researchers created data-controlled maps of human and chimpanzees ( Pan troglodytes ) brain with non-invasive magnetic resonance imaging (MRI) scans. They analyzed scans of 189 chimpanzees aged 9 to 50 years and 480 people aged 20 to 74.

Overall, they found that the brains of the two types were generally symmetrical across both hemispheres and had many similar clusters of anatomical structures, especially in areas of the prefrontal cortex. This region is involved in complex cognitive functions, such as language, working memory, time perception and decision-making, says study mitar Felix Hoffstaedter, a big data neuroscientist at the Jülich research center, which is based in Bonn, Germany. Damages in this region are connected to Alzheimer's and various forms of dementia, he says.

Then the researchers measured how much gray substance in the brain shrank over time - a sign of aging - in chimpanzees up to the age of 50 and in humans up to the corresponding age of 58. In humans, they found the strongest declines in the frontal cortex, including the prefrontal cortex, while chimpanzees experienced the strongest declines in a central structure that is involved in habitual education and reward -related behaviors, the striatum. Regions of the brain that are related to visual processing and motor skills were less susceptible to aging in both types.

Fast growth

Last the researchers rated which regions of the human brain were strongest compared to the chimpanzee brain and compared scans of human and chimpanzees in the equivalent age and gender. The fastest evolutionary growth had taken place in areas of the prefrontal cortex - one of the regions that are most susceptible to aging. A structure hidden deeply in the brain, which is involved in the processing of emotions and physical signals, called insula, also showed a quick evolutionary growth and an increased risk from aging.

"Evolutionary, the youngest, biggest changes are," says Hoffstaedter, "where aging takes place the most.

The researchers also compared chimpanzees with olivbaboons ( papio anubis ) and rhesusmakaken ( macaca mulatta ). Here they found no connection between the regions of the brain that had experienced a quick evolutionary expansion, and those who went through an accelerated aging process, which indicates that this property could be unique for the evolution of human brain.

Mars says it would be interesting to look at the age -related changes beyond the decline in gray substance, including changes in the connections between brain regions and gene ex speech.