Shankar Vedantam

But you say that the evidence doesn't fully support this explanation either?

John's point is not that medications and psychotherapy are ineffective and should be discarded.

He thinks they have helped millions and could help millions more.

His point is only that depression is not necessarily evidence that there is something wrong with the brain.

In fact, he believes the capacity for depression is wired into the brain.

From an evolutionary perspective, John, what do you think mood is actually doing for us?

You know, we talked with Lisa Feldman Barrett at Northeastern University some time ago on Hidden Brain, and one of her interesting and provocative ideas when it comes to the world of emotions is she argues that emotions are predictions about the world rather than reactions to the world.

They're basically guides that tell us, go forward, seek this out, this is going to be fun, be excited, have high energy, or on the other hand,

Withdraw, be careful, be afraid.

Something is dangerous here.

So when we think about emotions as predictors as opposed to reactions, that fits very well with your thesis that moods in some ways are a guide telling us what to do next.

To bear down on this just a moment longer, you told me how debilitating your depression was, how you felt like there was no end in sight.

You even had thoughts of ending your own life.

How could a condition that is so disabling, a condition that prompted you to consider suicide, how can this be understood as a beneficial adaptation?

So in some ways, what I hear you saying, John, is that, you know, as you discussed, the capacity for anxiety is a good thing, which is that it's important to be on the lookout for predators or threats.

And in our evolutionary history, this was a very useful adaptation.

But in the modern world in which we live, we are inundated with stories about things that could be threatening.

We're reading blog posts.

We're reading stories.

newspaper articles, we are watching cable television, we are on social media, and we are constantly being told about all the threats that are in our environments.