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- The human brain is amazing? How did it get that way? The answer may surprise you and make you appreciate your Thanksgiving Celebration even more.
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- Why are our brains better? First guess, our human brains are bigger. Someone estimated the average human brain has 100 billion neurons. About the same number as the number of stars in the Galaxy. About the same numbers as the number of planets in the Galaxy. If all brains are made the same the more neurons you have the bigger the brain the smarter you are.
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- But, that proportionality does not hold true:
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- Cows and chimpanzees have the size brains. We eat cows. There is no comparison.
- Human brains are --- 2.5 to 3.3 pounds
- Elephant brains --- 8.5 to 11
- Whale brains ------ 20
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- The size of your brain does not mean that you have more neurons!
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- Gorillas have much bigger bodies but their brains are 1/3 that of humans, about 30 billion neurons. Humans have 100 billion neurons. But, where did this number come from? Who actually counted the number of neurons? Suzana Herculano-Houzel from Ted-Talk actually did count them.
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- She reduced a brain to soup using detergents. The volume of the soup could be accurately measured. Then a measured drop could be put under a microscope. The number of neurons accurately counted. Do the math and she got 86 billion neurons in the average brain. 16 billion neurons were in the cerebral cortex.
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- Then there was the idea that all brains were made the same. But, when counting neurons was done on a rodent’s brain it was discovered to have larger neurons. So for the same brain size it has fewer actual neurons. A primate has much smaller neurons for the same mass.
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- A primate needs only a 3 pound brain to hold 86 billion neurons. That with a body size of 145 pounds.
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- A rodent would have an 80 pound brain and a body size of 89 tons to have 86 billion neurons. Obviously rodents and primates have different brains.
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- All primate brains are the same. It is just that humans have 16 billion neurons in their cerebral cortex which we use to do studies on other animals that they can’t do on us.
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- How much energy does our brain power take. It takes 25% of all the energy our body consumes. We primates need 6 calories of energy per billion neurons per day. Neurons are expensive to operate.
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- For gorillas to support their 30 billion neurons they must eat food 8 hours per day.
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- For humans to support their 86 billion neuron brains they would have to eat 9 hours per day of the same food. We don’t! How do we get away with 3 small meals per day?
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- ANSWER: We cook our food.
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- Cooking predigests the food. We get more energy out of every bite of the same food. Our ancestors invented this process 1,500,000 years ago. By cooking food, and 1.5 million years of evolution we got to have human brains. Now we do not have to eat 9 hours per day and we can spend our time for other purposes, like writing this review.
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- PROBLEM: Now that we have large brains we are not using them to keep from getting fat. We need to reverse the process and start eating more raw food like gorillas.
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- Cooking made us human.
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- No other brain cooks its food.
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- Happy Thanksgiving - be thankful for your brains and the calories to power it.
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(1) Came from Suzana’s Ted-Talk.
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or cell: 707-536-3272 -------------------------- Tuesday, November 26, 2013
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