The best books on Longevity

How did you go about choosing these books and what do they tell us, collectively, about longevity?

I chose them because they came at the topic of longevity from very different directions and I thought having an eclectic mixture of books would be the most interesting approach. They’re all very well written, too. Some books on longevity are completely unreadable, but these are not.

Do you think that there will always be a very clear limit to how we can extend our longevity or do you think that science and technology could dramatically expand the human lifespan?

I’m closer to the latter view than the former. I have a pretty well-known wager with a demographer about when we will have the first person live to 150. My part of the bet is that that person’s already alive. But I’m not on the side of those who say we’re going to live 1,000 years or become immortal. With laboratory animals, we’ve been able to make them live longer by about 20-25%. I think that’s a reasonable goal for humans. Talking about living forever I just think is wishful thinking.

Let’s move on to the books you’re recommending on longevity. First up is Lifespan: Why We Age and Why We Don’t Have To by David Sinclair.

This book is written by a genetics professor at Harvard who works in this area. It’s remarkable that a scientist has written such a personal book. It’s really about him and his research. What motivated him to get into the field was his grandmother who lived to 92, with the last decade of her life not being a good one.

It’s a linear description of how we’ve made progress in understanding the process of aging. He is one of these people who thinks that a 200-, 300-, 400-year lifespan is possible, maybe even more than that. Of the five books, this is the one that gets inside the cell to explain what goes on inside ourselves as we age. That is devilishly hard to write about in a way that’s transparent, but he has a real gift for analogy.

His particular view of aging is that it has to do with our genes not behaving properly and a gradual disorganization of the activities of the cell. There are things that can be done to fix that, and he’s really focused on one particular way of going about that, which is activating the protective molecules that our body has that are called ‘sirtuins’. The book is very much rooted in his own research, and he doesn’t hesitate to give health advice. But it’s perfectly reasonable advice—you know, eat a moderate amount, exercise, that kind of thing.

“With laboratory animals, we’ve been able to make them live longer by about 20-25%. I think that’s a reasonable goal for humans”

In terms of understanding the inner workings of aging, this is really an exceptional book. He talks about our DNA as being digital information, because there are these four letters that you have. Then there’s an analogue overlay, which is our epigenome. The analogy he makes is of a piano. It’s digital to a certain extent, you have a certain number of notes, and you can either be playing them or not. He talks about the epigenome as being the way that a pianist can play them softly, loudly or can emphasize them. That’s what goes wrong with aging. He describes it extremely well. He collaborated with a journalist, Matthew LaPlante, in writing it. I don’t know how much of the excellent writing is due to which person, but it is really well done.

In the latter part of the book, he talks about the consequences. If we did all live 200 years, would that be a global calamity or not? He’s on the side of, ‘No, that’s a problem we can deal with. Overpopulation won’t be a problem. Social security systems will not go bankrupt.’ He’s an extreme optimist, I would say, who argues that all problems will be solved.

What would he anticipate happening to birth rates in such a scenario?

He sees birth rates going down and down as people live longer and longer. That does seem to be true globally. The places with high birth rates are the places with low life expectancy and vice versa.

Let’s move on to Eat Like the Animals: What Nature Teaches Us About the Science of Healthy Eating by David Raubenheimer and Stephen Simpson.

This book is written by two entomologists, people that started off studying beetles and grasshoppers and things like that and weren’t that interested in nutrition. They’ve now become world-class nutritionists. This is probably the best book written entirely by scientists that I’ve read for a while. It is a fascinating read. It traces the authors’ gradual discovery of some fundamental laws determining the way that animals eat, starting with insects, but then moving into everything from baboons to gorillas to horses.

We’ve known since the 1930s that one way to make laboratory animals stay healthy longer and live longer is to allow them to eat much less. So if we take a laboratory mouse and feed it 30-40% less than it would like to eat, it will live 20-30% longer and stay healthy longer in just about every way that we can measure. What the authors have come up with is that it’s not so much the amount of food that’s important, but the composition of what’s eaten, and also the continuous availability of the food.

They’ve seen it in grasshoppers, beetles and baboons. Animals, including people, will eat to get a certain amount of protein. If they’re eating a very low protein diet, they will keep eating more and more and more till they get up to that level of protein. What’s happened in modern times is that we have ultra-processed, high-fructose corn syrup foods, so it takes a lot to get up to our protein quota. That explains a lot of overeating.

They got into the longevity business because somebody told them, ‘If you feed animals less, they live longer.’ They said, ‘Really? All of our research says it’s actually the protein.’ They did a bunch of experiments on fruit flies where they gave them different diets and looked at which ones lived the longest. It was the ones that had the proper level of protein, which is considerably less than if you gave the fruit fly what it wants to eat. What it wants to eat is the diet that will make it reproduce the fastest. That makes sense—that’s what evolution is all about, reproducing the most. But if you cut back the protein, it turns on all of these survival mechanisms.

So they divide the world into what they call the ‘survival pathway’ and the ‘growth and reproduction pathway.’ What we are really programmed to try to do is eat for reproduction, involving the growth and reproduction pathway. But if we want to stay healthy longer, what we really need to do is eat for the longevity pathway. One way to do that is to eat a low-protein diet.

The other way—and this is something that they didn’t really discover, but they talk about it—is that the timing of eating may be as important as the nutrients. One of the ways that this longevity pathway, which is a molecular pathway, gets turned on is by fasting.

I’ve done a lot of research in this area myself, on mice. When we’re restricting the mouse’s food it will eat all its food for the day in half an hour, and so it’s fasting for 23.5 hours. Suddenly people were wondering whether it might be the 23.5-hour fast that’s the important thing and not the amount that’s eaten. That looks like it might be the case.

That’s why you’ve had the development of all these intermittent fasting diets, where you only eat between noon and six o’clock or different amounts of time. It’s a fascinating development. The whole Sinclair book is a lot about genetics, but this book is all about nutrition, the way that nutrition feeds into health and longevity. They don’t make any grandiose predictions, they just say that if you want to maximize your longevity and your health, this is the proper way to think about what you eat.

Next up is The Human Advantage: a New Understanding of How Brains Became Remarkable by Suzana Herculano-Houzel. What does this book have to say about longevity?

This is a really intriguing book by a scientist who’s a neurologist. She didn’t start off being interested in longevity or aging at all. What she was really interested in was trying to understand why humans are cleverer than elephants. Elephants’ brains are three times bigger than ours, so why aren’t they three times as smart? What we have is a particularly big brain for our body size. If you took another animal that’s of comparable size, like a small zebra, it has a brain that’s a fifth the size of ours. So we’re really an outlier.

The way that people have always approached this before is by measuring the volume of different parts of the brain. What Herculano-Houzel does in this book is invent a way to actually count the number of brain cells in certain areas. You might think an elephant with a brain three times as big would have three times the number of brain cells, but it turns out that’s not true. She figured out that by basically turning the brain into soup—so you can’t do this on anything that’s alive—you can count the number of nuclei. What she discovered is that in the cortex, the thinking part of the brain, humans have three times as many neurons or brain cells as elephants do, which is remarkable.

For a long time, people have thought that brain size relative to body size also affects longevity. So one of the reasons that people are long-lived for a mammal of their size is because they have a bigger brain. I’ve always thought that’s speciesism or pride. What she found out is that if she plotted how long animals live against the number of cells in their brain, humans fell right on the line, rather than being this big outlier that they were previously. The other interesting thing that she discovered is that domesticated dogs have an incredibly large number of cells in the thinking part of their brain, the cortex. A dog has more cells, for instance, than a grizzly bear, which has a brain three times bigger.

The fascinating thing is the way that she came up with this technique and applied it to dozens and dozens and dozens of species and then explained the world. She thinks it’s also important in explaining development, how long it takes you to reach puberty. The more cells you have in the thinking part of your brain, the longer it will take you to reach puberty. So I just found her whole story of how she discovered this, and how she up-ended a lot of what people thought about what was going on in our brains by simply being able to count the cells, intriguing.

What are the implications of the findings she sets out in this book for shifts in human longevity?

I don’t think there are implications in terms of changing longevity. The implication is only in explaining why we’re so exceptionally long-lived, because we are the longest-lived terrestrial mammal. Actually, traditional societies and, say, hunter-gatherer societies were just a smidgen longer-lived than elephants. Elephants are pretty close. Bigger animals should live longer, and that’s probably one of the most robust patterns in nature. A horse is going to live longer than a mouse.

A pattern emerges in hundreds and hundreds of species’ longevity that we really didn’t appreciate before. So I thought it was fascinating from that perspective, the way she develops this idea behind longevity, that our brain really dictates everything that goes on internally and externally.

Let’s move on to Long for this World: The Strange Science of Immortality by Jonathan Weiner.  This book sounds like it’s very directly tackling this issue of extending our longevity.

Weiner is a Pulitzer Prize-winning author, and he decided he wanted to do a book on longevity. This is a book that really puts the entire field into a very interesting perspective. He starts out with the first gene that was discovered that changes longevity. Before about 1980, it was thought that a species’ longevity was essentially fixed by the number of brain cells or something. People thought you could modify it within certain narrow limits through proper healthy habits, but really couldn’t do anything fundamental about it. Then, in the 1980s, came a few discoveries where people purposely doubled or tripled or more, the longevity of certain experimental animals. They did this by altering their genes. In fact, one of the earliest studies showed that if you change just one gene, you could double the lifespan of an animal. Weiner covers that discovery, but he focuses a lot on personalities, and the personality that he finds most intriguing is Aubrey de Grey.

De Grey’s not really a biologist. He’s really a computer scientist, but he’s become famous for the outlandish claims that he makes about the future of human longevity. He’s one of these people who has said, ‘Oh, if you’re less than 60, now you can expect to live 1,000 years.’ That’s the kind of thing that he will say, and Weiner spent a lot of time in the pub with Aubrey listening to him talk, not blindly accepting what he says but finding it intriguing. Then he would go back and talk to scientists.

“The longest-lived mammal is a bowhead whale, which probably lives 250 years”

So, whereas Sinclair’s book is really linear in that it says, ‘we discovered this, and then we discovered that’—avoiding a lot of controversy in the field—Weiner covers it very well. He finds people who say, ‘Oh, Aubrey is out of his mind and this is why we think that.’ Another he does that’s really great is he puts the whole idea of immortality into a cultural context. What did different people at different times think about the prospect of immortality? What did the poets say about it? That’s something that none of the other books really do—trying to think of mortality in the larger human context. I really enjoyed that part of the book because he’s a very learned man. He is one of the few journalists that I would go out of my way to read, whatever he might come up with, because he did such a fabulous job of writing this book.

He was at a meeting that I was at just a few years ago, on bat longevity. Bats are the longest-lived animal, if you account for body size. The longest-lived bat lives 10 times as long as an average mammal, twice as long as a human, if they were the same size. He was really interested by this, so he showed up for all these highly technical talks. The thing that he was so good at was chatting with the scientists afterwards. This is just a wonderful book. If I were going to say read one book that will encompass the entire field, I’d say read this one, even though it’s 10 years old.

What’s the reason behind the bat being so relatively long-lived?

We don’t really know. They don’t have a particularly large cortex, the thinking part of the brain. They really are far off the scale. It may be because they fly. There’s a big pattern with vertebrates that fly. Bats and birds are particularly long-lived. We don’t exactly know why. Some people think it’s their immune system, because they’re so good at living with these hundreds and hundreds of viruses that they graciously gift to us from time to time.

With other animals that live a long time in the wild, we know how long they live from having captive colonies. But we have very few captive colonies of bats because they don’t do so well in captivity. So their longevity is exceptional, and it’s in the wild. Bats have to stay healthy, pretty much, to the bitter end. They have to be able to hear well, because insect-eating bats hunt with their high-frequency hearing, they yell and then they hear the echo. Our high-frequency hearing is the first thing that goes in humans. So bats are interesting on many levels—and Weiner is interested in all of these issues. It’s just a great book.

Does Aubrey de Grey have a coterie of scientists who support him or is he just considered by the scientific community in general as a bit out there?

I’d say it’s 80/20. 80% think he’s a bit out there. 20% think that he’s got something useful to say.

We’re now at your final book on longevity. This is Charlatan: America’s Most Dangerous Huckster, the Man Who Pursued Him, and the Age of Flimflam by Pope Brock. What’s this one about? It sounds fascinating.

This one is about a really intriguing character. The reason I included it is that people since Aristotle’s time have been saying ‘take my pill, use my potion, and you can live forever’ or ‘you can stay young forever.’ Those people are still with us. I’d say that once a week in my local newspaper, there’s a half-page advertisement on some crazy stuff that’s supposed to keep you young and healthy forever. These people are quacks. They’re quacks that walk the edge of legality. But this book is about probably the most intriguing quack of them all, John R. Brinkley.

He convinced people in the 1920s and 1930s that the way to preserve their sexual vigour was by transplanting goat testicles into men and goat ovaries into women. He had a remarkable piece of good luck, which was that the wife of one of the first men that he did this on had a baby within a year. He attributed this to the goat transplant, although now we know that the body must have immediately destroyed whatever he put in there because it saw it as foreign material. What made him so interesting is that he was so compelling. He got fabulously rich during the Depression by doing this. But he was an out-and-out quack. He killed dozens of people.

Eventually, he was brought down. He was penniless by the time he died because he got sued for wrongful death by individuals whose parents or spouses had gone to him perfectly healthy, to get their goat testicle transplant, and then died a few days later. It turned out he wasn’t even a legitimate doctor, he had gotten a diploma from one of these diploma mills.

But he was a marketing genius. He basically invented talk radio. In the 1930s he started his own station, with a medical call-in service where most of what he said people should do, after diagnosing them over the phone, was take his pills. He had this string of pharmacies that sold his pills. It turned out his pills were full of coloured water.

Eventually, he was brought down when Morris Fishbein, who was the editor of the Journal of the American Medical Association, wrote an article calling him ‘the most successful quack.’ Brinkley sued Fishbein for slander. It was that lawsuit that got him into court. It became widely known that he was a quack and that was really his downfall. He lost his medical license in Kansas, which is where he practiced for a long time. Then he lost his broadcast license, so he moved to Del Rio, Texas, which is right on the Mexican border, and started a high-wattage Mexican radio station. It was so high-wattage station that it was receivable in every state in the United States and in 15 countries. People said that if you had fillings in your teeth, and you lived in Del Rio, Texas, you could probably pick up his radio station on your teeth.

After he lost his medical license in Kansas, he got mad and decided he was going to run for governor. He made barnstorming public speeches. He would show up in an airplane in small towns and gave speeches from the airport, with all the people there. He came within a whisker of becoming the governor of Kansas. He probably would have done it if the election hadn’t been purposely rigged by the Democratic Party. At that time, he probably would have been the governor of Kansas, which shows that things haven’t changed so much since the 1930s.

How much was his pitch about longevity? Was he primarily telling people that the goat testicles would make them more sexually potent, or was the promise of a longer life just as important?

He started off with sexual potency but then he started adding more and more things. Eventually, it was ‘live longer,’ ‘cure arthritis, tooth decay…’ pretty much everything. Late in his career, he started doing vasectomies, or the opposite of the goat transplant.

He first started out during the 1918 flu epidemic that killed 500,000 Americans. That was the worst epidemic we’d ever had before COVID. He visited all the patients and did remarkably well. The local townspeople raved about what a wonderful doctor he was, even though he didn’t really have a medical degree. Apparently, he was very kind and reassuring.

He’s just a really fascinating character. He built the biggest mansion in Del Rio, Texas, during the 1930s when he was making all this money and I visited it a few years ago. I guess if you were a scoundrel long enough ago, you eventually just become a colourful figure. His mansion is now a Texas historical landmark and on a plaque there it says that he ‘engaged in controversial medical practices.’ That’s like saying a famous bank robber like John Dillinger engaged in ‘controversial banking practices.’

The book is so wittily written. It’s one of the few books that you will chuckle at repeatedly as you are reading it. But what it really shows is how desperate people are to live longer, to stay healthy longer and that they will believe anything. Even in the 1930s, believing that a transplantation of goat testicles into your own scrotum would make you live longer just seems crazy.

Before we go, tell me about your book and what you were looking to achieve with Methuselah’s Zoo.

This is my second book on aging. My first book was published 25 years ago. What this one does is march through the animal kingdom, describing the species that have exceptional longevity. The point of doing this is, first of all, to show people that there are certain patterns in nature. Some animals live an exceptionally long time, and stay healthy for a long time. But I also wanted to point out that current medical studies tend to focus on aging only by studying animals that are abysmal failures at it. Humans are not like that; we’re quite successful. If you look at our longevity, and the length of our healthy lives compared to the rest of the animal kingdom, we’re remarkably long-lived. The point of this book is to show that nature is smarter than we are and that if we really want to be able to change the length of human health and the length of human life dramatically, we need to look at the animals that are more successful than we are, rather than looking at the animals that are slightly less than abysmal failures, which is basically the way that the medical establishment is approaching it now.

I give some examples of how we might go about this. For instance, the longest-lived mammal is a bowhead whale, which probably lives 250 years. It’s hard to have a laboratory colony of bowhead whales, but there’s a lot we can learn from looking into the cells of a bowhead whale. If you have that many cells, 100,000 times as many cells as humans do, and you don’t get cancer in a year—each cell potentially could turn into a cancer—you must have some very, very good mechanisms for preventing cancer. The same goes for other aspects of longevity.

Then there are animals, like bats and birds, that could be studied in the laboratory. A good example that I like is that a mouse, which we can study in the laboratory, will live three or four months on average in the wild, and the longest-lived ones ever probably live a year, maybe a few months longer than a year. But the house sparrow, the most common bird in the world, can live up to 20 years in the wild. It does this despite having levels of sugar in the blood that would make it a diabetic were it a human, and a body temperature that would count as a dangerous fever. All these things should make it shorter-lived according to a lot of the ways we tend to think about longevity at the moment. But, in fact, it lives 20 times longer than a mouse. Those are the kinds of animals that we should be studying. I call them ‘exceptionally long-lived animals.’ Methuselah’s Zoo makes the case that those are the animals that really hold the secrets to longer, healthier human lives.