Name: Are We Programmed to Die? The Real Science of Aging
Uploaded: 2025-08-21T21:01:30.000Z
Duration: 7 min 30 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

So so I heard long ago and I checked it out and I think it's true that all mammals live for about the same number of heartbeats, except for humans who live two or three times that

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Except, if you go back far enough in time when we were just living in caves, we were right with all the rest of the mammals.

So first, is that true? Second, there are animals, not mammals, that live much longer than we do. I'm thinking of the Galapagos tortoise, for example.

Yeah, so do you guys study other animals to get insight?

So there is a whole field devoted to looking at lifespan of different species.

And you are right that at least among mammals, a Jeffrey West, who's written a book called Scale, shows that the number of heartbeats is roughly the same.

That has to do with the fact that smaller animals have a higher metabolic rate. They have a faster metabolism and and they almost need to because their surface-to-volume ratio is larger.

We did a whole explainer on surface-to-volume ratio.

And so they they they need to maintain a higher metabolic rate. That's one of the reasons that's only one of the reasons why they have higher heart rate That's not a reason why they should die sooner.

Ah, the why we should die die sooner is has an evolutionary Explanation and that is Evolution doesn't care how long you live.

It only cares about fitness fitness in the biological sense is the likelihood that you're going to be able to Successfully pass on your genes and people always misinterpret that as being physically fit or stronger or whatever I will love the fittest.

Yeah, George should have found a different word So evolution cares about fitness now at the same time for most of our history and Certainly the history of all other species resources are limiting and so You have to select do you put more of your resources into maintenance and repair of the individual?

Animal or do you put it into growth and reproduction?

There's always a balance if you if you have limited energy So in the case of a mouse, which lives about two years in the wild There's no sense in having a mouse live for 40 years because long before that it's going to be eaten.

Yep, exactly Or it'll die of starvation or a drought or something And so in the case of a mouse evolution has favored selection of a species that grows very quickly and reproduces prolifically That's a mouse if you get to a large animal like a bowhead whale Let's take an even even bigger than an elephant They can live for two three hundred years and they have a very relatively slow metabolism Wow, and even slower metabolism is not a mammal, but it's still a vertebrate called the Greenland shark 700 years Yeah a vertebrate living for 700 years very slow metabolism How do you know that?

We didn't even have marine biology 700 years ago They can do things like carbon dating and they cut one open it was a 700 rings So you've got the mayfly lives a day mayfly lives a day right and then between that you've gone from there to a Greenland shark And you're Galapagos and there are actually other animals that are thought not to even age Biologically, what's the emote like a hydra and the immortal jellyfish these things have an actual animal called the hydra.

No This is a freshwater small animal and okay, they're full of stem cells, so they're constantly regenerating themselves But if you followed an individual it would also age only very slowly.

It's just in the wild It it dies for other reasons before Actually aging.

Here's might be the only species That dies of natural causes in the world.

In fact, there's a book Written by Steven Ostad called Methuselah zoo Which way talks about all these animals in this book.

He he points out Methuselah zoo in Methuselah zoo he points out how all these species have such different lifespans and It's because of this evolutionary selection, but it's actually worse than that It's the fact is evolution will select for things that help you early in life Even if they cause a problem later in life So many of the things that cause aging are related to growth For example or to cancer prevention, you know prevention of or the or senescent cell These things all help us early in life and they're there a problem later in life But evolution doesn't care what happens to you when later we're not making babies.

Yeah, exactly Yeah, because that's the whole deal So what helps us survive in infancy and then go on to reproduction is the key component of our decline and demise not always not Okay, there are things that happen to us early in life that are selected for early in life that cause aging So the real deal is just keep having babies your entire life And then you you'll never age.

However, you will eventually kill yourself because of these kids So we're we're an outlier we're an outlier we live about twice as long twice as we would Based on our size, but only post caveman life, right?

So only I mean half of everyone died by 30 Yeah, and so we're not 2x other mammals at our size Yeah, and one last thing is there's a group of animals mammals the bats They live much longer they're about the same size as a mouse in terms of mass Yeah, if leader mouse, they they they live about 10 or 20 times as long as a mouse Mm-hmm, and the reason is they can fly around So that means two things they can escape predators more easily Yeah, and they can also forage over a much wider area for food So and and when they roost their roost in the ceilings of caves, so they're not safe accessible They've been designed to survive longer And so there is worth it for evolution to make them live longer because they'll still keep producing more babies Yeah, so you got to be grandpa Munster.