David Linden: The Brain is a 'Freaking Mess' | Big Think

There are a lot of things that are created accidentally in evolution. There are a lot of side effects. So you can evolve a pleasure circuit for adaptive things so they will eat food and drink water and have sex. And you can evolve social cognition, and then you can connect up your social cognition center with your pleasure center. And then you can take pleasure from positive social evaluation, which is something that you can imagine would promote group cohesion, and in hunter/gatherer societies would be adaptive.

But then you've built a machine that can be operated on in all kinds of ways in terms of culture and behavior. And we shouldn't fall into the trap and think that all those ways are adaptive or useful just because they've evolved. Evolution is a tinkerer and not an engineer, as Francoise Jacob famously said. And when you're a tinkerer, you throw things together to solve the problem at hand. You don't build elegantly, and you don't build the way an engineer would build to try to consider all the possible contingencies. You're just solving the one problem that circumstances have dealt you at this moment.

There's a tendency, particularly when looking at brain function, to be overawed by the brain, and, well, this is understandable. We say, well, human consciousness is manifest in this two-and-a-half pounds of tissue in our skull, and that's amazing. You say, that's amazing, but that doesn't mean that when you lift the hood and look at how it's built, either anatomically or electrically or genetically, that what you see is well-engineered. No. It's a freaking mess in there.

And it's a freaking mess both at these biological levels, and a lot of times it's a freaking mess at the behavioral level. We have two visual systems in our brain, a subconscious one and a conscious one. We have two auditory systems in our brain, a subconscious one and a conscious one. No engineer ever would have designed it like this. And then, the information from these two streams has to be fused to create our behavior. It's a total kluge, it works pretty well.

Our brains are pretty impressive in what they can do. The engineering behind it is completely insane. It never is what anyone would have designed given the chance, with all the time in the world on a blank sheet of paper.