字幕表 動画を再生する 英語字幕をプリント Aging is an age-related decrease in viability and increase in vulnerability. It means that, your capacity to respond to external stresses, and your capacity to function decreases with age. You become more vulnerable to diseases. One of the major causes of mortality in the elderly is influenza, which is just the common flu. The thing with aging, of course, it entails different levels and different organs and different systems in the body, which makes it very complex and relatively difficult to study. We actually don't know much about aging in the sense of its mechanisms. Why we age, what drives the process of aging from a cell or molecular perspective--is still relatively poorly understood. I mean, if you look at it evolutionary, our life span only recently has been so long. I mean the life span 150 years ago was something like 40 years old. And a thousand years ago it was maybe 25. When our species evolved and when most species evolved, most of the animals die when they're young. So there was really no pressure or very weak pressure, for us to avoid aging or to live longer. There are hypotheses, for example: That there's damage to DNA, that then probably affects cell renewal and stem cells, which, in turn, prevents repairing the body and contributes to loss of viability. Then there's the free radical theory of aging. This idea that as mitochondria in our cells, as they burn energy with oxygen, it generates these very highly reactive compounds, which creates damaging oxidative stress, which in turn accumulates with age, and that's the cause of aging. There's also things like the telomeres. So Telomeres are the tips of chromosomes and they shorten with cell division. But because it occurs with age as well, people say, well maybe, this drives the process of aging. So after about age 30, your chances of dying double every eight years This is fairly standard for human populations. No matter where you're from or where you live... In a third world country, they may have higher mortality to begin with, but you'll still see this exponential increase in mortality. But then you have very unique creatures. One example are birds. Now birds actually live longer than would be expected for their body size because, you know, they can fly and avoid predators. One of the species that we're interested in is an organism called the naked mole rat. Which lives over 30 years. Why? Because it lives in this protected environment... Then there is evolutionary reason, there is evolutionary pressure to live longer. One of the interesting things about the naked mole rat is that it's extremely cancer resistant. There's not been a single case of cancer in hundreds of naked mole rats. So longevity is plastic. Not only are there species that live much longer time than we do, but there are species that appear not to age. Like some species of turtles. Probably one of the greatest breakthroughs in the field so far is that you can manipulate individual genes and it has a very significant impact on aging. We know, for instance, that if you start manipulating DNA repair systems, sometimes, say, for example, in mice, you get what looks like accelerated aging. On the other hand, you can turn off a single gene in mice like growth hormone receptor and increase life span by 50%. There're also interventions that modulate aging. So the most famous of them all is Caloric Restriction: restricting the amount of calories animals eat while keeping nutrients like vitamins and minerals healthy. And this has been known for decades to extend life span in rodents like 50%. And they're healthier for longer and you know it's quite impressive. So one of the things, for instance, our lab does, is, well, if you know of a gene that mediates the effects of caloric restriction, then it may be a suitable target for you to develop drugs that target that gene in order to have the same effect of caloric restriction without you having to go on a diet. Which, let's face it, most people don't want to. We do a mixture of bioinformatics and experimental work. We try to look for common patterns amongst these genes as a way to identify new genes that modulate longevity. And we want to identify which genes are regulating the other genes, so, key regulators of the whole pathways. And the thing to remember about aging in general is that it's very time-consuming and expensive to do experiments. That's one of the problems of aging research. If you could slow down the process of aging just by seven years, this would reduce in half the incidence of age-related diseases at every single age. This would have a massive impact on human life span, on human health. I generally make the analogy of the Wright brothers They used to look at birds and they said, listen, there are birds. They are heavier than air, and they can fly. So if birds can fly, so can we make airplanes. There's no law of nature that says that aging is immutable. On the contrary. What we know now is that aging is surprisingly plastic. In the sense that it can be manipulated by genes, it can be manipulated by evolution, it can be manipulated by diet. When I was younger, I think maybe ten years old, I realized that everyone ages and dies. And I thought, well, why should that be, I mean, can't we do something about it? So I thought, well, I'll do it. I'll study aging and I'll figure it out and I'll find a solution for it. So people don't have to age and die.