Archive for August, 2016

How the brain works, addendum: why you can’t live forever.

Wednesday, August 24th, 2016

Before the internet was anybody’s bad idea, I wrote this:

And I’ve had a lot of time to think about it more over the years, and I have a few thoughts to add…

You can’t live forever. ‘You’ being the important word here.

There’s been a lot of talk lately about the science of getting older and how to put it off as long as possible.

There may be a magical point in time where life expectancy starts to increase at more than 1 year per year.

Anybody alive at that time (and able to afford whatever treatments are required) can conceivably live forever. I mean eventually you’ll get hit by a bus or taken out by some nasty disease, but the dying-of-old-age problem will have been solved.

Firstly if you think about it for a few minutes, you probably don’t want to live forever anyway, but I imagine you can come up with reasons besides the ones I’m about to offer.

Consider the idea of ‘you’. You are a unique individual person made up of your education and experiences and dna yada yada yada. I’m sure lots of philosophers have gone over this endlessly before me. The simple version of the problem is ‘what defines you’ changes. If you’ve ever looked back at your teenage years and thought “boy that time I did yada yada was really stupid” you might realize that given the same circumstances, you would decide differently. Because you’ve learned from your mistakes and you’ve realized a better decision making process given that scenario and you would do things differently.  Is that the same you? How many experiences do you have to have, and how many different decisions would you have to make before you started to think you were not the same person you were when you were 18.

But that’s a philosophical argument about not living forever, here’s a more concrete one.

Quite simply: your brain will run out.

When you are born you are a randomly firing set of neurons with just enough firmware to keep you breathing and eating. Watch any newborn, this is pretty obvious.

As you grow you learn to see and to hear and to do the most amazing of human skills: recognize patterns.

Then you learn to remember.

After that, it’s just a matter of gathering more and  more patterns and experiences until somebody hires you.

After that you can pretty much coast for a few decades.

But then what. The human brain is probably not a fixed size, but it does have to fit in your skull. Maybe some really smart people co-opt some space from their throat or something, but at some point the brain can only get so big.

Unless there’s some weird hyperspatial transference going on (and I have it on good authority there isn’t) there is a finite amount of information you can store. There are a finite number of neurons that can fire to enable you to think, absorb information, tie it to an existing pattern and impress it to long term memory. If you learn something new, at some point, something’s got to go.

I imagine if anybody could figure it out, we’d find that the human brain has evolved quite an impressive compression algorithm. One that, much like common picture compression, is lossy. It ties patterns together and makes a few distinctions between them, but  certainly does not store a perfect representation of all of your memories, each separate and complete.

You don’t know what you don’t know, and you don’t even know what you did know but forgot. And you don’t know what you forgot, so you can’t even attempt to reproduce it. The error correction is limited.

People tend to misremember things, some worse than others, but nobody’s perfect and as it turns out, the laws of physics do not require people to have perfect memories. People make mistakes, not everything works out correctly all the time. And it’s okay, the world keeps spinning. But I digress, because I like to.

So here it is, you can’t live forever simply because on some level, your brain will stop working well. I have this vague idea that as you get older, some of the thinking neurons are sacrificed for memory neurons, but I don’t have any good evidence of that. But even without that at some point, your brain will fill up and you either won’t remember things as you would have before, or you’ll start losing old memories, or most likely, both.

Somebody once explained to me that a great way to tease out the possible solutions to a problem, is to make the numbers in your problem really large, and then it becomes obvious where the solution to the problem lies.

Given the decrepit state that your brain will be in after a few thousand years of live-forever treatment, it’s hard to imagine that you will still be you, or even able to think correctly.

No, you can’t live forever.