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O demónio é a maquina


Anyone whose resolve to exercise in 2013 is a bit shaky might want to consider an emerging scientific view of human evolution. It suggests that we are clever today in part because a million years ago, we could outrun and outwalk most other mammals over long distances. Our brains were shaped and sharpened by movement, the idea goes, and we continue to require regular physical activity in order for our brains to function optimally.


To explain those outsized brain, evolutionary scientists have pointed to such occurrences as meat eating and, perhaps most determinatively, our early ancestors’ need for social interaction. Early humans had to plan and execute hunts as a group, which required complicated thinking patterns and, it’s been thought, rewarded the social and brainy with evolutionary success. According to that hypothesis, the evolution of the brain was driven by the need to think.

But now some scientists are suggesting that physical activity also played a critical role in making our brains larger.

To reach that conclusion, anthropologists began by looking at existing data about brain size and endurance capacity in a variety of mammals, including dogs, guinea pigs, foxes, mice, wolves, rats, civet cats, antelope, mongeese, goats, sheep and elands. They found a notable pattern. Species like dogs and rats that had a high innate endurance capacity, which presumably had evolved over millenniums, also had large brain volumes relative to their body size.

The researchers also looked at recent experiments in which mice and rats were systematically bred to be marathon runners. Lab animals that willingly put in the most miles on running wheels were interbred, resulting in the creation of a line of lab animals that excelled at running.

Interestingly, after multiple generations, these animals began to develop innately high levels of substances that promote tissue growth and health, including a protein called brain-derived neurotrophic factor, or BDNF. These substances are important for endurance performance. They also are known to drive brain growth.


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