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The human body allocates 20-25% of its total resting metabolic rate to the brain, compared with 8-10% in other primates and a mere 3-5% in other mammals.
Thus we view the brain as a rather energy-hungry supercomputer.
This analogy with an electrical computer is a good one. The greater a computer's capacity, the more electrical power is required to keep it running, and the larger the electrical supply cables need to be.
It is the same with the brain. The higher the cognitive function, the higher the metabolic rate, the greater the blood flow and the larger the arteries.
The evolution of the human brain is unique among animals. We have looked at the size of the carotid arteries in 34 species of living primates that represent evolution toward the great apes and hominins.
Among these representatives of primate evolution, both body size and brain size increased, but body size increased faster. The blood flow to primate brains increased roughly in proportion to brain size. Only in the hominins do we see that blood flow increased faster than brain size, which indicates that the brain was not only developing in size, but in usage as well. And that shows our ancestors were getting smarter.
Would routing a firehose directly from our heart to our brain make us smarter, then?
(Score: 3, Interesting) by TheLink on Sunday March 26 2017, @04:14AM (1 child)
(Score: 0) by Anonymous Coward on Sunday March 26 2017, @06:34PM
Sorry but the fossil evidence points to the plains apes getting to the top of the food chain with tiny brains. They could as we still can out distance run any creature on earth. Our bodies were evolved to run. Brain size clearly had nothing to do with just about all our body's evolution when you look at the modern evidence. Just watch PBS Nova on it and that is enough to get the point across.
The big problem is that there are no signs of how these running apes developed larger brains. They didn't cook food with their tiny brains. The best theory I've read which I currently subscribe to is that these apes got to the top of the food chain and multiplied until resources became a problem -- as happens with any imbalance in a species but for them their tribes spread out as well as fought creating multiple evolutionary pressures on mental adaptability.
How did stupid running apes multiply so well? Well, by gathering over a wide area and hunting much more--- every animal runs away from a pack of rock throwing chimps.... and will run to the point of exhaustion. Make that a group of stick/weapon using chimps and even lions would lose from prolonged attacks -- not smart enough to realize fighting it out is better than getting over heated. BTW, the other big evolutionary thing we inherited besides being the best joggers is we SWEAT to cool off better as well! It makes sense doesn't it? Before you think it takes much brain power, look into how wolves will get prey isolated and doggedly wear it down working as a team.
So... why didn't dogs become smart? Why didn't we get tougher and stay stupid?