Why We Get Old & How We Can Stop It - Dr Andrew Steele | Modern Wisdom Podcast 265

Toward the end of the book, I start talking about what our cure for aging is actually gonna look like. And I think it's gonna be much more complicated than anything we've talked about so far. The reason I've got some faith that it's gonna happen is because we're undergoing a computational revolution in biology at the moment. You know, even if we don't get to general intelligence, I think we're gonna get to a point where AI programs are able to interpret this huge sort of torrent of data that biologists are producing in a way that humans just can't understand.

What is aging?

That is an excellent question. There are many, many different ways you could define this, and I think e- every different scientist could give you a different answer. But I've got two ways of thinking about it, one of them statistical, one of them biological. And the statistical way of thinking about it, which I think is the most sort of catchall definition of aging, is it's what happens to your risk of death with time. So the longer you've been alive, how much does your risk of death increase? So let's take the example of humans. Um, if you're in your 30s, your risk of death is about one in 1,000 per year. If you're lucky enough to make it as far as 80, your risk of death goes up to 5% a year. So it's- it's, you know, hundreds of times more. And what... Uh, s- yeah. Yeah, so what that means actually, if you look at the stats, is... Can I start that again? 'Cause I think it's not hundreds of times, is it? The difference between five and 1,000 is on- it's 200. It's 200 times more. I'm right. (laughs)

That's fine.

Sorry. Let me do that-

It's correct.

Let me-

It's correct, Andrew. We're- we're- we're-

(laughs)

We're, the- the- the internet, you're here because you're a scientist, not because you're a mathematician.

(laughs) And what you find actually is the- the better people are at maths, in terms of, like, the- the proper theoretical hardcore maths, the worse they are at mental maths. And you find yourself second-guessing yourself all the time.

(laughs)

If you get a proper hardcore number theorist, they can't add two and five.

(laughs)

(laughs)

I remember my-

So that-

My old housemate did a PhD in pure mathematics, and he once ordered a four-seater taxi for five of us because apparently in pure math, you count from zero.

(laughs) Yeah, yeah, it's off by one error. Classic in computer programming as well. (laughs)

Unbelievable, man.

So-

You spend all this time doing maths, you can't count to five?

I know. Got a PhD, can't even manage it. So what, where was I? Yeah, yeah. So the- so humans, the- the sort of way to sum up all that stuff that I just failed to add up in my head is that our risk of death doubles every eight years. So you can say in some sense, our rate of aging is encapsulated in this number. We're saying that if our... That's, you know, this... It's called the mortality rate doubling time. So how long does it take your mortality rate to double? And if you look around the animal kingdom, this isn't universal at all. For mice, it's a matter of months. Um, but if you look at something like a giant tortoise, um, which you'll find on the cover of my book, and the reason is that they're what's called negligibly senescent. They have a risk of death which is constant with time. So effectively, their mortality rate doubling time is infinite. And that doesn't mean they're immortal. It doesn't mean they're gonna live forever, but what it does mean is it doesn't matter how long ago they were born, um, their risk of death stays the same. So that's the statistical definition of death. The biological definit- sorry, of aging. The biological definition of aging, I'd say, is to look at the individual components of the aging process. And there was a paper published in 2013 called The Hallmarks of Aging, and it lists these nine different changes in your cells, in your molecules. Um, and they- they tend to increase with age, all of these things. Um, they tend to... If you accelerate these changes, then the animals will have their aging accelerated, so they'll die more quickly. And if you slow these changes down, then the animals get less disease and die more slowly. So that's the sort of criteria by which they define these different hallmarks, which are a sort of more nitty-gritty, molecular, what's-actually-going-on definition of aging, as opposed to that high-level statistical one we started with.