Venki Ramakrishnan
Appearances
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
That's the heart of what we call messenger RNA or mRNA, which again, nobody had heard of a few years ago, but then COVID came along and everybody started shooting mRNA into their muscle. And of course, what that mRNA had was the gene for the spike protein of coronavirus. So when it went into our cells, our ribosomes latched onto it.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
and made spike protein and displayed it to our immune system to react. So it's a perfect example of how all this molecular biology knowledge that we had accumulated over decades suddenly became useful. during a pandemic. People think that the vaccine took 11 months to develop, but actually it took decades.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And it just so happened that we were at a time, at a point in time where we could very quickly implement these platforms.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It's jumpy in the sense it's stochastic, but it's fairly deterministic. To give you an example, the error rate in making a protein is typically one in a thousand to one in 10,000. And that's quite a low error rate. It's much lower than the best peptide synthesizers that humans can make in the lab, have a much higher error rate and are much slower.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I mean, a bacterial ribosome adds about 20 residues a second. So if you made a movie of a bacterial ribosome, it would just be a blur. In fact, I have a movie that I sometimes show, and I show it slowly with all the players coming in and out. And then I say, okay, now I'm going to speed it up to real time. And it's just a blur. So it's an amazing machine.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And yes, it's stochastic in the sense binding is stochastic. But there is a deterministic... direction to it. And that's because energy is used at each step. And that's what thermodynamically drives it forward in the forward direction.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, so the fact that ribosomes can crystallize suggests that ribosomes are largely identical But there's now a debate in the field.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
There are a group of scientists who believe that ribosomes can be specialized, that in some cells you may get subsets of ribosomes which translate particular mRNAs or translate under certain, you know, translate meaning translate the genetic information into protein. So that they work under certain circumstances. And this field of specialized ribosomes is still somewhat controversial.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But it does have some strong advocates. And I think... I would say the jury's still out, but there is some evidence for specialized ribosomes.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Very similar. They're not exactly the same because there'll be small genetic differences. So just like, you know, for example, a mouse may be well over 95% or so identical to in some ways to humans. But of course, that same degree will apply to ribosomes and ribosomal proteins. But I will tell you one thing, the core of the ribosome, the part where the amino acids are joined,
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
to during stitching together a growing protein chain, you're going to add amino acids to the growing protein chain because amino acids are the building blocks. So that part where it's joined or the part where the genetic code is recognized in the ribosome, those parts are highly conserved. They're even conserved across kingdoms.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So there are only very small differences in the so-called peptidyl transfer center, which is where the amino acid bond is formed, peptide bond is formed. There are very subtle differences between, say, bacteria and humans. But overall, the ribosomes of bacteria look very different. For example, the human ribosomes are...
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
almost twice as large, and they've expanded both their RNA and protein components considerably.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Environmental factors, viruses. So I think part of the reason that eukaryotic, that is a translation in higher organisms, with a nucleus is more complicated, is because there's more regulation in higher organisms. And Initially, biologists thought that almost all of the regulation of genes had to do with how much and when you made mRNA from a section of DNA.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that once the mRNA was made, the ribosome inevitably had to just do its thing, almost like a slave. But that's not how it is. It turns out that control exists both... at the mRNA production level, but also at the protein production level. So what we call translational control. And this means that the cell has ways of deciding when to start making proteins.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
or it has ways of detecting when protein synthesis has gone wrong, when ribosomes have stalled because they've run out of amino acids. And what do you do about stalled ribosomes? So there's a whole series of control mechanisms and regulatory mechanisms. And the interesting thing is viruses will often hijack the ribosome. So they will shut down what's called the initiation machinery.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
This is what tells the ribosome where to start on the mRNA. It doesn't start right at the extreme end. It has to start somewhere and then go along until it finds the first ribosome. codon, the first amino acid signal to be made. And that process of initiation is very complex. And what viruses do is they shut down the host initiation. So none of the host genes can be made into protein.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And then they have alternative ways of recruiting ribosomes to their own mRNA. And so they effectively hijack all of the ribosomes to make their message. In fact, the first gene product of coronavirus is something called NSP1. What NSP1 does is shuts down initiation from host mRNAs and somehow still allows coronavirus to make its own genes, you know, proteins from its own genes.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So there's a lot of... controlled regulation that's going on. And so even though the structure of the ribosome, the first structures came out from bacteria in about 2000, and then gradually we learned more and more about structure, the field is still going forward in all these complicated directions.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I don't think so. But as I've mentioned that there is this subset of the ribosome community that believes in specialized ribosomes. And they do have, you know, some data to support their view. So I think that it's still a matter of debate in the community. And it could be that there are specialized ribosomes. I wouldn't be completely surprised.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Although if you had to ask my personal opinion, I think that We still need to have stronger evidence for that.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
People have already done that. So the structures of the ribosome do describe it in atomic detail. So we know the X, Y, and Z coordinate of every atom in one state of the ribosome. But remember, the ribosome is a highly dynamic machine. It moves around. It undergoes all sorts of processes. conformational changes. And so it's very much like watching a complicated machine which moves around.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Take a car, for instance. You have pistons that move around or a rotor that moves around in an electric car and wheels move and steering wheels move. So it's not a static object. And the ribosome itself is not static. It has complicated movements of its various component parts.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And what people are trying to do now is to simulate, using molecular dynamics, how the ribosome might move over time and as things bound to it, for example, the mRNA bound to it and the small adapter RNA molecules called tRNA molecules that bring in the amino acids to add to the protein in the ribosome.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So all of those things can change the conformation, the shape of the ribosome, because it's a dynamic machine. And people are trying to simulate that in computers.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I have to say, you know, I was a grad student in physics and I was trying to do condensed matter theory. And it was just so hard to make progress and do something interesting. And I used to subscribe to Scientific American. And I don't know if you remember, but in those days... all the articles were written by the primary scientists themselves, of course, with editorial help.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It was really very much a first person account. It was really thrilling. But what impressed me was that every issue had big questions in biology that were being answered left and right. And I thought, well, you know, this is probably where I should be
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So right after my PhD, I went to grad school again at UCSD to study biology because I felt I didn't know any biology, so I didn't want to do a postdoc right away. Right, right.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, and I have to say, I thought I was in the middle of a revolution, but that revolution seems to still be going. It's been going for a long time. I would say ever since the discovery of the gene in the late 19th century, there's just been this steady onslaught of advances in biology. I liken it to how physics progressed very steadily after Galileo and Newton. and just kept on going.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And then when it was stalled, then suddenly you had quantum mechanics and relativity, and then there was another big wave. So I think biology is sort of behind physics by maybe a couple of hundred years. So it's not as mature a field as physics. And that's probably why I think physics is also harder, because it's more mature and the questions are harder.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
That's another way of thinking about it. Yeah, that's true.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Well, I think it started because I wrote my first popular book, which was called Gene Machine, which was about the race for the structure of the ribosome. It was meant to capture some of the frankness of the double helix, which I have to say I read as a student of physics. For the first time, it gave me some idea of the thrill of physics. you know, a biological question.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And I know it's a very controversial book, but it's influenced lots of people, including Jennifer Doudna, who in the preface to her own book says that's a book that really stimulated her to become a scientist. So although it's got its, you know, downsides, you know, Jim Watson can be frank, but also unnecessarily nasty. I wanted to capture the frankness without the gratuitous nastiness.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so that was my experience of writing that book. And I found I enjoyed the process of writing about a complicated subject in molecular biology for the general public. Then I thought, well, what could I write about now that would be really timely and that I would have something to say? And the thing is, as I mentioned, protein synthesis is central to aging because proteins do a lot of things.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And if the process gets disrupted or becomes less optimal, then it leads to aging. So I was very, very close to the field, even though I don't particularly work on aging. And aging, of course, is a big existential question. We may be the only species that's aware of mortality. Animals may know about death. They can certainly sense death.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But I think there's no evidence that they know about mortality in the sense that we humans know that we're all going to die, that we're not going to live past 120, at least given current medicine and biology. So that's influenced us greatly.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Ever since we were aware of it, if you look at all the ways we try to avoid death, you know, building pyramids and mummifying ourselves, and also a lot of religions actually deal with what happens when you die. And they're all different religions will have different ideas of what will happen, but they all view it as some sort of transition.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
rather than a finality so it is a question that's bothered us ever since we became aware of it but It's only in the last 50 years that biologists have made real advances in understanding what is the aging process. It's not just wear and tear. It's much more complicated than that. And what is the aging process?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Why is it that some species live for a day or two and others live for several hundred years or possibly, in the case of plants, even a thousand years or more? And why is there this huge spread? What causes that? What causes us to eventually die? It's a big existential question. Then there's a practical thing, which is societies are getting older. And as societies age, what happens is that
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
you have to deal with an aging population because fertility rates are going down. The population distribution is being more and more shifted towards older age groups. And if these older people require lots of care or poor health, that's not great either for them or for society. And so there's a big push from governments to do something about improving health in old age.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that requires understanding the whole problem of aging. And so there's a lot of research, but then now you have injection of a lot of private money. There are 700 companies doing some sort of longevity-based biotech. Billions of tens of billions of dollars going into this. A lot of it funded by tech billionaires from California. And I like to joke that these are guys who...
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
just are afraid of getting old. They like their life and they don't want the party to end. And so they're funding, they can't buy youth, so they're buying research into aging. And that's also distorting the field. It's generating huge amounts of hype because now there's money involved.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so I thought as somebody who doesn't have a personal skin in the game, and since it is this big question, I thought I could look at the current state and talk about how we came to our state of understanding, which is interesting in itself, but also what are the realistic prospects and what's just a lot of hype. So I think that's the sort of goal.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And it turned out to be a much bigger problem than I imagined because aging basically encompasses all of biology, right from DNA all the way to cells and tissues and organisms. So- But it was fun to write it.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yes, I do say that, actually. We all have a skin in the game in that we're all aging, and we'd like to do something about it if we can.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And of course, the other skin in the game I have is I like to say I'm not selling anything, but of course, I'd like the book to sell.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
They need to sort of... Oddly enough, I found many unicellular organisms do die. For example, budding yeast. where you can clearly separate the mother cell from the daughter cell, they do die. The mother cell only can undergo a certain number of divisions, and then it's basically senescent and dies. And interestingly, people have even done this with simple bacteria like E. coli.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
The trouble with E. coli is you can't tell which one is the mother cell and which one's the daughter cell. But people figured out that when E. coli grows, it grows in one direction. It doesn't grow in both directions at the same time. So there's a new part of E. coli and there's an old part of the E. coli when it's when it grows.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Then when it divides, one half, one daughter cell inherits the new part. The other daughter cell inherits the old part. And if you keep repeating this by very carefully producing these E. coli in thin tubes so you can keep track of it, it turns out that the old E. coli eventually dies. So it's pretty amazing. So I would say almost everything dies, even even unicellular organisms.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But of course, that's not what we mean when we say death. And this actually, you know, since we both have a connection with the Santa Fe Institute, this really, I absorbed this through a series of workshops on aging at the Santa Fe Institute, where they think of aging as a Biological aging is a special case of aging of everything, all complex systems.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
For example, companies or societies, cities, they all grow and they age and then they die. So in our case, what do we mean when we die? It's a particular weird thing. It has to do with us as an individual, and that's also hard to define. What do you mean by an individual? Because the strange thing is, When you're alive, millions of cells in you are dying all the time.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And in fact, many of those cells are required to die at appropriate times. If they didn't die, you as an individual would die. So that's one side of the story. The other side is that when you die, most of the cells in your body are still alive. In fact, that's the reason why we can donate our liver and kidney and heart to transplant recipients when we die. And so here you have this paradox.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
When you're alive, a lot of you is dying. When you're dead, most of you is still alive. So what does this mean? It means that we can no longer function coherently as a whole individual. And we worry about it because we are aware of ourselves as an individual. We have consciousness. But you can imagine species that don't have consciousness.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
The extreme are, for example, plants, but also simple animals. They might never actually, even if they had a nervous system, they might not actually even think about death. It's just something that happens. So it's a peculiar situation that we're in that we obsess about mortality and death.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Oh, definitely. I think, for example, when you get to sexual organisms, then you have a clear separation between the germline, which is responsible for reproduction, and the rest of the body. And in a sense, there's a part of us that has been alive for billions of years because we didn't come out of nothing. We came out of a cell, which came out of a cell, which came out of a cell.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So there's a direct lineage all the way back to a few billion years that did not die. And so the germline, there is a chapter in my book which is called, I think, the immortal germline and the disposable body or soma. And so that is really a dichotomy in complex organisms. And in a way that's different from say bacteria or other organisms.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And what is interesting is that germlines aren't actually immortal, but we've evolved so that germlines are much better protected. For example, DNA damage or other kinds of damage are cause of aging. And germlines are protected much better against DNA damage and other kinds of damage. The other thing that happens is that germlines are selected almost ruthlessly.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
For example, when a female fetus, in the early embryonic stages, there are almost a million eggs or so. But of course, you know, you don't have, those million eggs are not, you don't have a million ovulation cycles. You know, in a human woman's life, maybe a few hundred eggs are, you know, secreted during menstruation, I mean, during ovulation. So what happens to all the others?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Well, the others are all ruthlessly selected because There's a whole process of selection from the oocyte, the precursor of the egg, all the way to the final egg that ends up ready for fertilization. And at each stage, it's monitored for defects and ruthlessly pruned out. And of course, sperm in males is also ruthlessly selected for, you know, millions of sperm and they all have to swim.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And if they can't make it and they are in any way defective, they just don't have a chance to undergo fertilization. And even after the embryo is formed, many embryos spontaneously abort without the mother even being aware of it in many cases. Some cases they are aware if it's later and there's a miscarriage. And so there's ruthless selection there.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And even within the developing embryo, defective cells are destroyed. So I think this... I thought about why is it that we get old, but when a child is born, it's not born old. So it's as if the biological clock has been reset every generation. And that's because of this combination of protection and against damage for the germ cells and ruthless selection.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I think it's that combination that allows us to have an embryo that is, you know, looks, you know, it's gone back to state zero. But of course, all of the little tags on the DNA have been erased. These tags are markers for aging. They've been erased and and then reprogrammed to start from scratch.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So so it's all this combination of things that goes on to to reset the the biological clock every generation.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, so this has to do, you know, we talked about how some species live only a day or two and others live several hundred years. Well, you know, Jeffrey West, who we both know from Santa Fe, has written a great book called Scale. And in that book, he talks about relationship between lifespan and parameters like size.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It turns out that large mammals live, on average, much longer than small mammals. Now, why would that be? Well, it's because evolution simply doesn't care how long you live. It cares about fitness, which is how likely are you to pass on your genes? How successful are you going to be at passing on your genes? And so I think...
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
If you're a mouse, there's no point in spending a lot of resources to repair and maintenance because we do have sophisticated repair and maintenance mechanisms. Otherwise, we wouldn't even last a year. We would be dead before that. We do have this very sophisticated mechanism, but that takes energy and takes resources.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And in a small animal, it's not worth it because the animal is going to be killed off by a predator or die of starvation or some other cause. So there it's more advantageous for evolution to put resources into rapid growth and reproduction. And that's what a mouse does. And at the other end, you have things like a bowhead whale or a Greenland shark, very slow metabolism and
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
well, especially the Greenland shark has a very slow metabolism, large, and can produce offspring over a long period. So you have these opposite extremes. And the interesting twist on this are bats. So bats weigh about the same as a mouse, the same size as a mouse, but can live 10 to 20 times as long. And the reason is bats can fly, so they can escape predation.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And they also can forage over a much wider area and are less likely to starve. So it makes perfect sense that you would have this evolutionary thing.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
This is called Pitot's paradox, after Pitot, who was the scientist who first formulated it. Because an animal like a whale or an elephant has thousands of times more cells than a mouse.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
and so if even one of those cells became cancerous and triggered a cancer then the animal would die so you would think those animals would be more likely to get cancer instead it's a mouse that's more likely to get cancer that has to do with the fact that you know all these repair mechanisms don't work as well in a mouse because evolution doesn't care how long a mouse that a mouse should live that long
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But anyway, so it turns out that there's a DNA response repair mechanism. One of the genes involved is called P53 or TP53. And this is involved in sensing DNA damage and triggering repair mechanisms. And it turns out that elephants have something like 20 copies of this gene.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So they're much more efficient at detecting cells where there's been some problem with the DNA and destroying them so they don't become cancerous. And people have looked at whales, and whales also seem to have alternative repair pathways that presumably prevent them from getting cancer. That is the way that evolution has dealt with the cancer problem.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And yeah, that's right. It's not exactly a cure, but it does give you some understanding. And it also shows you the relationship between aging and cancer. It turns out many of the... things that cause aging, like telomere shortening, these are the ends of our chromosome, get a little shorter each time the cell divides.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And when they reach a critical stage, the cell stops dividing and goes into a state called senescence, and then it's eventually destroyed. And you would ask, why would it do that? Why not? And if you were to let cells have the ability to proliferate indefinitely, then if that cell became cancerous, it would be a cancer risk.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so this idea that you destroy that ability to divide forever in most of our cells and restrict it to just a few cells, like our stem cells, that's probably evolved as a cancer prevention mechanism. And that, again, is because you don't want to get cancer before you have a chance to reproduce.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And once you've reproduced, okay, the consequences that you age, that's okay because you've passed on your genes. That's the evolutionary game.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
No, there are many different aspects to aging, and they happen from the molecular level all the way to the level of tissues where cells talk to each other. So just to give you an example, we could start with DNA. which encodes proteins and so on. And DNA damage is one of the primary causes of aging. And of course, we have extensive repair mechanisms, but the DNA repair mechanisms themselves
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
can break down with aging. So it's a kind of auto catalytic or accelerating phenomenon that DNA damage becomes increasing with age. But that's a cause of aging. And then the proteins that are made using genetic information They often, the quality of those proteins goes down with age. Our ability to recycle proteins that are defective also goes down with age.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So there's all those levels at what I call the protein level. And then this also affects organelles like our mitochondria, which are our organelles in our cell that are responsible for energy production. Of course, some of you may be interested that mitochondria actually were bacteria that were swallowed up by an ancestral cell of ours.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And the two somehow managed to live in a symbiotic state ever since. But mitochondria now control a lot of the health of the cell, including a lot of metabolic pathways. And so if mitochondria become dysfunctional, that's another cause of aging. or the lysosome, another organelle which is responsible for removing the junk in our body.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So all of these proteins that accumulate that are defective or entire organelles that are defective are taken to the lysosome and recycled, basically degraded and recycled. But that process called autophagy can also decline with age. And then cells themselves can decline. So I pointed out that when cells are stressed, when they sense damage, they go into a state called senescence.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
These cells can't divide, but they, in turn, they secrete inflammatory molecules. And early on in life, that has a purpose because this senescent cell is saying to the immune system and other repair cells that, look, I'm damaged. This site around me is probably damaged. Maybe there's a virus attack. And so come here and repair the damage.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so in the process, they repair the damage and the senescent cell is destroyed. But as we get older, the ability to destroy the senescent cells has also declined. And of course, more and more senescent cells are formed because other processes stop working and more cells go into senescence. So you get this buildup of senescent cells and inflammation. So that's another problem.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And then stem cells, which are the cells which are responsible for regenerating tissues. So they have to do two things. They have to regenerate themselves, and they also have to regenerate the tissue that they are sort of in charge of. Early stem cells can make any kind of tissue. So in an early embryo, you have what are called pluripotent stem cells. These cells can make anything.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But later stem cells, later in development, they specialize. So some stem cells can only make skin and hair. Others can only make cells of the nervous system. Of course, there are many different types, but still a subset. Others can only make cells of the blood, and that includes the entire immune system and our red blood cells. So these stem cells themselves
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
decline with age because many of them go into senescence. And so you get a depletion of stem cells. And the quality of the remaining stem cells is also not as diverse and not as good because they're often descended from a few clones which don't have necessarily the optimal properties. So that's another cause of aging. And that leads to tissue loss.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
For example, a common problem with aging is loss of muscle and frailty. So you can see that at every level there's an effect, but each level is not independent. They all interact with each other. And so there's this complicated web of things happening at different levels of complexity.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, it does. People have made a lot of progress. For example, I mentioned senescent cells. So amazingly, people have been able to target senescent cells using some particular biomarkers, things characteristic of senescent cells. And when they destroy senescent cells in, say, mice, aging mice, the symptoms of aging improve in those mice. And so that's one way.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
that one of the more exciting and more challenging ways to deal with aging is to reprogram cells. So you take cells and you reprogram them so they go slightly backwards in development. So effectively they become like stem cells. So you're reactivating stem cells for different types of tissues.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that, I would have thought that was almost science fiction, but recently in the last few years, a number of papers have come out doing exactly this in mice. And showing that the symptoms of aging have improved in these mice. But of course, reprogramming cells raises the risk of cancer. It also raises the risk of how do you do this in a body in a holistic way?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Because our different organs age at different rates. And how do you ensure a kind of systemic recovery? rejuvenation, if you like. I think people don't like that word. Some people like it. Just to popularize it. So it's a challenging but hard problem. It's another way to maybe tackle some aspects of aging.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It's unlikely to, although that also has a real scientific basis. And many decades ago, people actually connected a young mouse with an old mouse.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
By connecting their blood systems together. And some decades ago, people found that actually the old mouse benefited from the young blood And the young mouse actually deteriorated as a result of the old blood. And so this was an amazing finding and, of course, raised all sorts of questions like what's going on in blood and what are the factors in blood.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Maybe there are factors that prevent damage or factors that cause damage in old blood or maybe activate stem cells in young blood. There could be a number of scenarios. And so there's a huge field that's looking for these factors and trying to identify what is different about young and old blood. And of course, of the many differences, not all of them will be relevant.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So they have to figure out which factors are actually relevant to aging. And then they have to find out how they work. And then they have to figure out if they could actually use it in some therapeutic way. But the amazing thing is as soon as this... these findings were published by Randall and others at Stanford, they started getting all sorts of weird phone calls from creepy people.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And there were all these companies that sprang up which would collect information blood donation, well, they would buy blood from young donors and then sell them at presumably at a huge markup to, you know, rich old people who wanted a transfusion. And there's no evidence that any of this actually worked in humans, you know, and certainly not over the long term. So that's how it is.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that's a... I have to say that's characteristic of the aging field. Scientists will make a completely bona fide discovery. in animals, the original scientists often, but not always, okay? I should say there are a number of scientists who are also, you know, have a kind of agenda. But by and large, scientists will be somewhat cautious and want to proceed rigorously.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But then outside parties will jump on it and then try to commercialize it or hype it up. or use some sort of supplement that they think will activate this phenomenon. So there's a huge amount of hype in the field. And I've tried to kind of try to separate the rigorous science and the biology from the hype.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Because even knowing the rigorous biology, there are lots of things we can do that will help us age more healthily. So it's not as if You know, there's nothing we can do, and we have to wait around for this industry to come up with something. There are things we can do now, and then potentially there may be more powerful things later.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yes, that's very perceptive. So that was a question people asked that maybe the young mouse was actually acting like a dialysis machine, for example, cleaning out the old blood because its organs and kidneys were better and so on. But what people did was then they took actual young blood from the young mouse without connection. and gave it to an old mouse and did vice versa.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And there, it's interesting, they found that the old blood actually was more deleterious to the young mouse than the young blood was beneficial to the old mouse. And that perhaps why these transfusions
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
aren't quite having as big an effect as you as as you might have hoped you know brian johnson the tech billionaire who spends i i guess i'm told he spends like two million dollars a year on various longevity treatments and diagnostics And clearly, he has an agenda. He says he thinks of himself as an experimental animal out at the forefront.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And he wants to try all the stuff and be an aging pioneer, if you like. Anyway, he did this intergenerational transfer where he took blood from his son, gave it to himself, and then he gave blood to his father. So it's a sort of three-generation. I joke he was keeping it all in the family. Anyway, but after a while, he was also measuring all these various markers of aging.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And I think he came to the conclusion it wasn't having much of an effect, and I think he stopped.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I think, well, there are a number of possibilities. I think to me, cellular reprogramming is perhaps, if it pays off, one of the most powerful ways of doing it. But I will tell you, you could reprogram many tissues perhaps, but reprogramming the brain is going to be a real challenge because the brain doesn't naturally regenerate.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
There's only a very small amount of new neurons being synthesized compared to things like skin or blood or even liver. And of course, when neurons decay, or become dysfunctional, how you would reprogram them or even replace them, it's not at all clear. And you would have to do this in a way that, you know,
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
maintains the connections between neurons and their states, because that's after all what determines the workings of a brain. And I think that is going to be a huge challenge. And there is this worry that we're all getting older, we're staying healthy. Eventually, if it means that we're going to come down with dementia, And, you know, the incidence of dementia is growing tremendously.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It's already the largest killer of an old age in the UK. You know, it surpassed other causes. That could be a ticking time bomb. And so I'm optimistic that we'll be able to improve health in many ways in old age. I'm not so optimistic about this, you know, eventual thing of extending life dramatically. I think that's going to be much harder than people think.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Well, cellular reprogramming is, you know, I mentioned how you start with a fertilized egg and it slowly develops. And as it develops, the cells become more and more differentiated into different types. And And eventually you still have stem cells, but then those stem cells are differentiating into the final tissue. Those final tissues can only divide a certain number of times and then they die.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And then they have to be replaced by stem cells. And also those tissues can't be any other kind of cell, okay? So cellular reprogramming would be taking one of these final tissue cells, like a skin cell or an epithelial cell from your gut, and programming it to go backwards in that development process. And that means changing which genes it's expressing.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And what's amazing is that it, and this is why Yamanaka won the Nobel Prize, is that it only takes four factors to to take a final cell all the way back to that early pluripotent cell, which could create any type of cell, okay? The downside is that if you do that, you often end up getting cancers.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
If you start developing those cells in a tissue culture, they often will develop tumor-like growths and so on. So I think, you know, That's both a promising and a challenging approach. And it's the one thing that actually reverses the process. And one reason that I am perhaps somewhat optimistic is, remember Dolly the Sheep? I do. Dolly the Sheep was cloned from something like a skin cell, okay?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And It was a sick sheep and it had all sorts of problems. It had shorter telomeres than normal, and it died at about half the age of a normal sheep. And everybody went, aha, that's because you started with an adult cell, which is already old and damaged. And then you tried to grow a new animal out of it. And so of course you haven't reset the clock.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Well, it turns out Dolly was only one of a cohort. There were other sheep like Dorothy and Daisy and Debbie. They gave them all D names for some reason. Anyway, it turns out most of these sheep were normal. Of course, you have to realize that the frequency of success in a cloning experiment is very small. most of those experiments fail and don't grow into adult animals.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But of the ones that actually made it into adult animals, a number of them had normal lifespan and apparently normal health. So at least in those cases, and of course there was ruthless selection involved because as I said, most of these embryos failed to take. But nevertheless, it is possible, at least in theory, to reset the aging clock, just as we naturally do every generation.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that involved wiping out the signals, the programs of which genes are expressed, back to an early embryonic state. And that program is different from, the skin cell makes only a subset of genes, that we have. And it's a different subset from a brain cell or a heart cell or a blood cell. But you could take it all the way back.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
that you need tissue regeneration. And it turns out that, and you need to recycle bad products. You need a number of things that have to happen that become dysfunctional as we get older. And it turns out one of the things that allow us to be healthier in old age is caloric restriction. Again, there's a big debate about that because they're always comparing
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
animal that gets just the bare number of calories it needs to live without starving. The animal is not losing weight and becoming lethargic. It's getting the bare minimum, though, to live. And they're comparing that with Animals that can eat all they want, an ad libitum diet. And there's always a difference.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Now, some people have argued, including Leonard Hayflick, who was the first person to discover that cells can only divide a certain number of times, which eventually was explained by telomere loss and so on. But that guy died, by the way, Leonard Hayflick died in his 90s, only about a month or two ago. Anyway, he was a skeptic.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
He said, all this shows is that an all-you-can-eat diet is bad for you. Because in the wild, you never have all you can eat. This is a problem of a plentiful food supply, civilized society. But nevertheless, caloric restriction makes a difference, and it does affect a number of pathways. And people have found out that there are drugs that can inhibit some of these pathways.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And those drugs will often have some of the benefits of caloric restriction, maybe many of the benefits of caloric restriction. One of them called rapamycin was discovered in this very odd way. It has a fascinating history, how it was discovered. But it inhibits a major pathway called the TOR pathway. but which is also restricted by caloric restriction, inhibited by caloric restriction.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so when they tried to give rapamycin to older animals, those older animals did seem to have improved health and improved symptoms and also lived a bit longer. So it's become a darling of the aging, some of the aging research community. But rapamycin is also the reason that it was known as a drug was because it's immunosuppressant.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It's given to transplant recipients to prevent organ rejections. And you wouldn't want to take an immunosuppressant all your life. I mean, if you're an organ recipient, you would, because otherwise you'd die, you'd reject your organ. But the equation's different if you're normally healthy. Why would you want to risk infection? And then it has all sorts of other side effects.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So the aging, some of the rapamycin advocates would argue that, well, maybe there's a dose at which it has the benefits without the side effects. Or maybe we can find compounds similar to rapamycin that don't have the side effects but have the benefits. So that's an ongoing research field. And I would say that's a valid field.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So the other thing is exercise. The other thing is exercise. And exercise, it turns out... helps to repair and renew the body. In fact, It's involved in regeneration of mitochondria, regeneration of muscle. So it has a huge number of benefits. And the last leg of this trio is sleep. So we think of sleep as something that maybe mammals do or animals with a brain or eyes do.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It turns out sleep is highly conserved, even very simple organism sleep, even things like single-celled animals sleep. have a daily fluctuation in the genes they express, which is the equivalent of sleep. And sleep would normally, you would have selected against it because you're vulnerable when you're asleep.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And the fact that we all sleep and need to sleep means it's performing an essential function in life. There's a fascinating book called Why We Sleep by Matthew Walker. And, you know, he goes into a lot of this detail. It turns out during sleep, we're doing a lot of maintenance and repair, both of our nervous system, but also of our cells. And sleep is essential for healthy aging.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And so this trio, I would say, is a great place for us. You don't have to restrict your calories to the absolute minimum you need, but As long as you avoid bad food and being overweight, and especially obesity is a real problem with all sorts of things, including aging and cancer.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So if you can avoid that, eat moderately and eat healthily and exercise regularly and sleep, that's a great way in which we can take control. And these might have been longstanding pieces of advice, but what's different now is we understand the molecular basis for why they're actually working. So we know that they do actually work.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Well, the goal of the aging research community is to give you a pill so you can have that blueberry pie and ice cream.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
I personally think that our mortality is what gives our lives meaning. there's a famous law, Parkinson's law, that work expands to fill available time. Now imagine if you had all the time in the world, you would just procrastinate. And I think that's a serious problem. It gives us the drive to get things done. It gives us some purpose in life. Now, I also think there's another problem.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Let's say we all started living very, very long lives. And if you don't want a population growth, explosion, then what you have to have is very slow turnover. And this means the same people are hanging on with very slow change in society. And you would have, I think, a stagnant society. Because even though we're living longer, it does turn out that we're at our most creative when we're young.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
This is true in many of the sciences, but oddly enough, it appears to be true even in areas like literature. Many authors write their best work when they're young. Then they go on to produce good work, but it's not necessarily their best work.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And Ishiguro, the writer, Kazuo Ishiguro, had an idea that he says, when you're young, it's not just about your cells and your DNA damage and things like that, but rather you're experiencing everything fresh for the first time. You're more objective. You're not biased. You haven't accumulated biases. And so that leads to creativity.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Step into a world where stories come alive. On Audible, there's more to imagine when you listen. Immerse yourself in captivating audiobooks, including master storyteller Stephen King's latest short story collection, You Like It Darker. Let King's chilling tales transport you to realms both haunting... and thrilling. With Audible, you're not just hearing words, you're experiencing them.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
It's interesting because You know, everybody thinks they know what DNA is. They've all heard of it. Even if they don't actually know what DNA does, they know it has something vaguely to do with our genes. But if you ask them what a ribosome is, most people have never heard of it. Never heard of it.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Another possibility is that as we get older, short-term memory is one of the things to go. And maybe the creative act requires holding disparate facts in your head in an attempt to synthesize some new thing. And if we're not able to hold them while we're trying to synthesize it, that makes creativity harder. So there are a number of explanations.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And I also think if you look at social change, things like that, it's often driven by the young. And there's a whole question of intergenerational fairness. If old people just hang on to power positions, et cetera, there's this problem of turnover. And we in academia are only too well aware of this. And so I think... For all sorts of reasons, it's problematic.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But of course, the flip side, as someone pushed back against me, was that, look, 150 years ago, we were living half as long as we do now on average. Of course, the oldest people were still living quite long, but on average. And now we're all living about twice as long on average. Do you think we should go back to the older time because there was more regeneration, faster regeneration?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Or would you want to go back? And of course, none of us would, right? And tomorrow, if somebody came to you with a pill and said, look, this is the result of anti-aging research. It's going to give you 10 extra years of healthy life. Nobody wants to live unhealthy, but say 10 extra years of healthy life. Most of us would take it. And that's the paradox.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
We as individuals don't necessarily do what's best for we as a species or as a group. We haven't evolved that way. And this is the problem behind all sorts of social problems, including climate change. We're unwilling to do the things individually that we know might help us as a society.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Absolutely. I'll tell you one thing that I didn't say apart from the trio. There are other things that help with aging, and that is avoiding social isolation. It turns out reduces mortality. But having a sense of purpose also reduces mortality. That, to me, was a bit surprising. But in hindsight, perhaps not so surprising because it gives you that will to go out and do things.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So, you know, one of the purposes in your life is your podcast. And it definitely, you know, thinking about it, thinking about what new topics to discuss and whom to invite. You know, those are all things that are going to keep you young.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And the thing about the ribosome is without the ribosome, DNA would almost have no meaning because DNA encodes genetic information. but it's really the ribosome that reads that genetic information to produce that whole orchestra of proteins that makes a cell actually be able to live, carry out all the reactions, but also build all of the structures in the cell.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Thank you.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
All of those structures are either made of proteins or built by proteins. So I like to say that almost everything in the cell was either made by the ribosome or was made by enzymes that were made by the ribosome. So you can think of it as the sort of mother or grandmother of all things in the cell. And it's also older than DNA. It goes back to an RNA world.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Before DNA was used to encode genetic information, life probably began as an RNA cell. world because RNA can both carry out catalysis or chemical reactions, but it can also store genetic information. And the earliest ribosomes were probably made just of RNA and were somehow used to make small random proteins. And eventually a coding mechanism evolved so that you started making coding proteins.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
So that was the beginning of genetics, of gene-encoded protein synthesis. And it's an enormous machine. It was discovered in the 50s, but a human ribosome has about half a million atoms. And so even though it was discovered in the 50s and then people started to figure out what it was made off and what it did, the exact mechanism, how it actually worked remained a mystery for a long time.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And that's because when you have a big complicated machine, if you don't know what it looks like, it's very hard to make detailed hypotheses about how it works. It's amazing that biochemists made as much progress as they did without ever having seen what a ribosome looked like.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
You know, that just shows how clever many biochemists are in doing the kinds of experiments where they could make inferences. But ultimately, solving the structure was a game changer. And it allowed people to do much more detailed mechanistic experiments to understand how it all worked. And now, you know, it's led the way to understanding how the ribosome is regulated, because that's
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
you know, you mentioned my book on aging, the connection between ribosomes and aging is that the regulation of ribosomes start to unravel as we get older. And so a lot of current works about ribosome regulation and regulation of protein synthesis.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, that's true. And I think the science of visualization in molecular biology has advanced tremendously. I mean, first it was X-ray crystallography. And now more recently, there's cryo-electron microscopy. And also now predictive algorithms for protein domains and proteins using AI, which is also having a big impact in structural biology.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
From thrilling mysteries to heartwarming romances, there's a story waiting for everyone. As an Audible member, you choose one title a month to keep from their entire catalog, and new members can try Audible free for 30 days. Visit audible.com slash WonderyPod or text WonderyPod to 500-500. That's audible.com slash WonderyPod or text WonderyPod to 500-500.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
Yeah, the ribosome, as I said, it's large in molecular terms, but of course, it's only a couple of hundred nanometers across. So you can't really see it with an ordinary microscope, but you can see them under an electron microscope. And the big progress in the visualization field
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
is that electron microscopy is advanced as a result of better detectors, better algorithms, faster detectors so that they can freeze the movement of particles while they're collecting the image. And that means that you can get high resolution atomic level images without using crystallography. So you don't even need crystals, which is what you needed for x-rays. And that was a big bottleneck.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
And the other thing about electron microscopy is you need tiny amounts of sample, and they don't even have to be pure. You can sort the particles computationally. So that has been a big game changer. And it struck me, there was a paper in BioRxiv just a few months ago where they had looked at ribosomes inside a cell. So they hadn't even broken open the cell to purify it.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
They just looked at thousands of ribosomes inside cells classified them into groups, and got a whole bunch of structures, each of which represents a snapshot of a ribosome. So what took us years of work, I mean, these guys did, you know, within weeks.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
But that's just how science is, right?
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
We did the painful way of... producing crystals which would take eight weeks to grow and were tiny. Then you'd have to take them to a synchrotron, these powerful x-ray sources, and hit them with x-rays and then analyze the data. And then eventually, if everything went well, you would get an image. And the first images were quite fuzzy. They were what we call low resolution images.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
You couldn't see atomic detail, but you could see broader features, like you could see a double helix for the RNA. RNA, of course, also forms double helices like DNA. And when we saw that first double helix in the image of the ribosome, that was a very exciting moment because we knew that it was real because it had the features that you would expect. So it was a very exciting time.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
You know, I think... You know, smaller pieces of RNA had been already crystallized and their structures determined. So we knew that that's what RNA double helices should look like. I mean, the thing about the ribosome is not the structure of the individual pieces, but rather how they were put together in this large complex and how they interacted, how the different pieces interacted.
Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas
291 | Venki Ramakrishnan on the Biology of Death and Aging
That's still basically the story. Of course, there are some genes which are never made into proteins. They stay as RNAs. And there are other parts of DNA and RNA that are involved in control, you know, start here or do this in response to this stimulus. So there are lots of control signals, but the part that codes for the protein