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Home » What is So Special About The Human Brain? By Suzana Herculano-Houzel (Transcript)

What is So Special About The Human Brain? By Suzana Herculano-Houzel (Transcript)

Suzana Herculano-Houzel on brain


What is so special about the human brain? Why is it that we study other animals instead of them studying us? What does a human brain have or do that no other brain does?

When I became interested in these questions about 10 years ago, scientists thought they knew what different brains were made of. Though it was based on very little evidence, many scientists thought that all mammalian brains, including the human brain, were made in the same way, with a number of neurons that was always proportional to the size of the brain.

This means that two brains of the same size, like these two, with a respectable 400 grams, should have similar numbers of neurons.

Now, if neurons are the functional information processing units of the brain, then the owners of these two brains should have similar cognitive abilities. And yet, one is a chimp, and the other is a cow.

Now maybe cows have a really rich internal mental life and are so smart that they choose not to let us realize it, but we eat them. I think most people will agree that chimps are capable of much more complex, elaborate and flexible behaviors than cows are.

So this is a first indication that the “all brains are made the same way” scenario is not quite right.

But let’s play along. If all brains were made the same way and you were to compare animals with brains of different sizes, larger brains should always have more neurons than smaller brains, and the larger the brain, the more cognitively able its owner should be. So the largest brain around should also be the most cognitively able.

And here comes the bad news: Our brain, not the largest one around. It seems quite vexing. Our brain weighs between 1.2 and 1.5 kilos, but elephant brains weigh between four and five kilos, and whale brains can weigh up to nine kilos, which is why scientists used to resort to saying that our brain must be special to explain our cognitive abilities.

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