The costly evolution of the brain • The brain is the most expensive organ in the body, accounting for about 20% of the metabolic budget. • Understanding the evolutionary and developmental records can help determine an organ’s most important job. • The main function of an organ can be determined through studying its records. Transcript: Speaker 1 Oh no, it’s really not the case. Am you know, when i started to think about writing this book, i asked myself, why do we even have a brain? Mean, a brain is very expensive. So that three pound blob of meat between your ears costs about 20 % your metabolic budget. So it’s the most expensive organ you have in your entire body. And i thought, well, why did brains evolve like they’re very, very expensive. And you can’t really say why anything evolved. I mean, you can make up stories, and you can make educated guesses, but you can say, you can look at the record, the evolutionary record, the developmental record, and you can say, ok, Well, what is, what is an organ’s most important job? What is its main function? (Time 0:00:56)
The Evolutionary Purpose of the Brain Transcript: Speaker 1 Oh no, it’s really not the case. Am you know, when i started to think about writing this book, i asked myself, why do we even have a brain? Mean, a brain is very expensive. So that three pound blob of meat between your ears costs about 20 % your metabolic budget. So it’s the most expensive organ you have in your entire body. And i thought, well, why did brains evolve like they’re very, very expensive. And you can’t really say why anything evolved. I mean, you can make up stories, and you can make educated guesses, but you can say, you can look at the record, the evolutionary record, the developmental record, and you can say, ok, Well, what is, what is an organ’s most important job? What is its main function? And when you look at the evolution of the brain, it’s really pretty clear that the brain’s most important job is not thinking, and it’s not feeling, and it’s not even seeing. It’s running the systems of your body to keep you alive and well so that you can do your most important job, from, you know, evolution standpoint, which is to pass your genes on to the next Generation and help that generation survive to reproductive age. (Time 0:00:56)
The Function of the Brain: Understanding Metabolism and Mental Health Transcript: Speaker 1 When we look at the function of the brain, the brain’s main function, which tells us something about its structure, how to understand its structure and the way that it works, we realize Both those questions are completely wrong. Because heart disease is fundamentally a metabolic illness, and so is depression. So i’m not reducing everything to your metabolism, but i’m telling you this is a really important factor that is overlooked. Seratonan, for example, which is a chemical in the brain which is there is i balance in this chemical im in depression. People think about this chemical as the happiness chemical, but you know, it actually functions as a metabolic regulator in your brain and your body. And it evolved for that purpose. It evolved as same thing with dopomine. It’s not a reward chemical. It’s a chemical that helps you to expend effort in the service of obtaining a reward, or or really engaging in any behavior that will cause you to spend a lot of energy, a lot glucose and Oxygen and so on. So the question, asking the right questions about illness and health really require that we understand how brains work. And our own experience of the world and ourselves in the world is not always the best guide to understanding what’s happening under the hood, say iben. (Time 0:03:55)