Transcript

Brains are the most expensive Oregon we have in our whole body. Brains cost about 20% of our metabolic budget. And they're only three rounds in size. So they're really, really expensive. So I sort of wondered, well, why? Why did brains evolved in the first place? And what is the brain good for? The Triune brain is this idea that your brain evolved in three layers, you have the inner lizard brain, which is supposed to contain circuits for instincts. Layered on top of that is thelimbic system, limbic meaning border, and this was supposedly evolved in ancient mammals.

And then layer on top of that is the big cerebral cortex that's supposed to be the home of circuitry for rationality. For many years, this was the kind of dominant view of brain evolution and brain function and brain development really, both reptiles and mammals evolved from fish, they're actually on different branches. And so the idea that you would have an inner lizard actually doesn't make any sense. From an evolutionary standpoint, the only animal on this planet that has a lizard brain is a lizard.