What street did you grow up on? What was your high school's mascot? What's your mother's maiden name?

I'm not trying to access your bank account. I'm trying to prove a point. Except when you forget your

password, all of this information is completely useless to you as an adult, and yet you've retained

all of it.

Despite not having answered at least one of those questions for years in all likelihood,

your neurons have all the right pathways lined up and ready to fire the right answer as quickly and easily as you could correctly answer the question, what's your name?

Your brain isn't like a hard drive.

It won't run out of space.

You don't need to clear out old memory to make room for more.

No matter how much you add a whole bunch of stuff,

much of it not very useful, is going to stay.

Your brain does filter out some things deliberately,

as we'll talk about soon,

but it's not in the business of deleting whole folders of junk

because it needs room for more info.

But why not?

Why don't our brains run out of room?

Why doesn't your brain delete some of the less useful stuff to make more space?

Well, that's like asking, why don't we make golf balls smaller so we can have more space for them on the course?

Your brain is enormous, one of the largest in the animal kingdom,

and it contains about one billion neurons, each connected to about a thousand other neurons,

and this web of connections stores all the information in your life, from your opinions about

...