Q. But there are an incredible number of good reasons to want a much longer life.
A. Absolutely. You’d still have the youth and energy to reinvent yourself. You wouldn’t be stuck in choices you didn’t like. You could start over. So radical life extension is not black and white—it’s a fascinating mix of fantasy and nightmare.
Q. Which are the most promising theories on aging?
A. The leading molecular theories are:
- Chronic inflammation, which seems like it’s clearly bad for you.
- The error catastrophe theory still has life in it. That’s the theory that our cells are gradually accumulating mutations as we get older, and even those that don’t lead to tumors can still derail the works.
- There’s the garbage catastrophe hypothesis, which theorizes that our cells are filling up with junk—the submicroscopic waste our cells can’t clear out. The more molecular junk there is, the less efficient cells are, and the more frail we grow.
Q. Are there other kinds of theories?
A. There are also evolutionary theories, such as the disposable soma theory that holds that humans didn’t evolve to live forever because we were going to get chewed up by a lion or freeze to death before we got back to the cave. So evolution never worried much about what the body suffered after our 20s, it created a disposable body; all that matters is that you grow up to the age of reproduction.
Q. The disposable soma theory seems to ignore one not-so-minor detail: how beneficial grandparents are to their children.
A. That’s right, and the grandmother hypothesis is also alive and well. That’s the theory that we live so much longer than the other primates because we can pass on our culture and wisdom as we grow older, that we have value long past the age of reproduction. It’s a virtuous cycle—the more culture we have to pass on, the more value we have, so the longer we live. Families with long-lived, helpful grandparents do better than families who don’t.
Q. You spend a lot of time talking about the work of theoretical biologist Aubrey de Grey, the fairly controversial gerontologist.
A. Aubrey has a gigantic beard, always a beer in his hand and talks a mile a minute. But I don’t want to just make him out to be a joke. I don’t think he’s going to be remembered as one of an infinitely long line of charlatans going back to Dr. Faust.
Q. Which theory of his seems to hold the most promise?
A. He and a group of eminent gerontologists published a big policy paper. They argue that we need to be pushing research on all these fronts—looking at calorie restriction [CR] and drugs like resveratrol that mimic what calorie restriction might do. That’s where a lot of the serious research money is now—in the search for calorie restriction mimetics. And then there’s Aubrey, who is promoting a less fashionable approach that may turn out to be the better strategy. Aubrey thinks we shouldn’t intervene in metabolism, like the CR mimetics, but instead focus on cleaning up the junk metabolism produces.
Q. He makes it sound so easy! Clean up all the garbage in the cells, and suddenly we can cure any disease. Is there anything to it?
A. At least in principle, it’s an easier strategy than tinkering with our metabolism. As he says, the junk is inert. If you could clean up the junk, maybe the body would function much more smoothly for much longer. Serious gerontologists are willing to talk about that as a plausible strategy. But he’s awfully optimistic about how quickly we can get from here to there—maybe in as little as 15 years.