Life expectancy for humans has increased dramatically since 1900: Life expectancy at birth was just 47 120 years ago, and it's 79 today. Dr. Laura Carstensen, who directs the Stanford Center on Longevity, was recently a guest on Morningstar's The Long View podcast to discuss some of the key reasons for those dramatic strides. She also delved into some of the factors that contribute--or don't contribute--to longer lives.
Christine Benz: Most everyone listening will be familiar with the factors that tend to be associated with living longer: family history, diet and exercise, not smoking, and so on. Are there any factors associated with longer life spans that might be surprising to the general population?
Laura Carstensen: Yes, and you're completely right that some of the obvious ones are: try to stay healthy, don't smoke, don't drink too much, get some good genes going. Although, we have learned that genes are not as important as we thought they were to life expectancy. The way we live our lives, lifestyles, contribute much more to how long we live.
One of the surprising contributors to life expectancy, in my view, has been purpose in life. Those people who feel like they matter to a cause or to other people to their families, those people who have a real sense of strong purpose, live longer than people who don't, controlling for health and lifestyle and drinking and smoking. So, you control for all those variables. And the people who say, "There's a reason for me being here," are ones who do better and live longer.
Jeff Ptak: Maybe you can talk about the connection between wealth and longevity. Obviously, wealth shouldn't be mistaken for purpose. But what leads to any connection between them? Is it mainly access to education and things like better healthcare, or are there other factors?
Carstensen: That's a great question. As you noted, education and wealth tend to travel together. People who have high levels of education are more likely to have higher incomes. And so, it's been difficult to tease those things apart very well. But sociologists have done a good job of it, statistically anyway, and it looks like a lot of what contributes to people living healthier longer is education. What helps people live longer after they get sick tends to be wealth, but education seems to be a better predictor than money for staying healthy. But once you get sick, as most of us do at some point in life, then wealth/income predicts better than education, how quickly you will decline.
Benz: At a certain level of wealth, do we max out on the longevity benefits--wealth and education, I should say--or are the wealthiest and most educated among us also the most likely to live the longest?
Carstensen: They're certainly correlated at the population level. And there are some conflicting findings in the literature about how much money contributes to life expectancies. There are some people who think it kind of levels past a certain income. Say you are upper-middle class, you don't see a lot of increase as you get into the very super wealthy. There are some other studies that find, however, that with every $10,000 of income, people live longer. So, there's some disagreement here. And then most studies aren't really including those people who live in austere poverty. And if you include those people, clearly living in poverty takes a big hit on life expectancy, not a big surprise there. So, it kind of depends on what groups you're looking at. And as I say, there's some disagreement about it. But at the general population level, yes, having money helps people live longer, it predicts living longer.
Ptak: To build on something you mentioned a moment ago, focusing on that opposite extreme of the wealth spectrum--life expectancies in the United States have begun to decline for people at the lowest income levels. What are some of the reasons that this is happening? And do we have a longevity divide in the same way we have an income gap?
Carstensen: Yes, and yes, we do. Many of your listeners will have seen these headlines prior to COVID, where we saw life expectancy fall in the United States. And I'm glad you asked this question, because I think there is some misunderstanding about it. And including within the scientific community, some people have taken this decline in life expectancy as somehow meaning that, again, we've reached the limits of how long we can live. And now we're even seeing it tick down. But if we look at the reasons for the life expectancy decline in the United States, it's really being driven by particular subpopulations, mostly in the Appalachian regions, some southern parts of the country, where we see high rates of drug use and poverty. And we also see higher rates of homicide and suicide. And so, the kinds of factors that are contributing to this tick downward in life expectancy in this country are not due to some general shift downward. But rather, again, if we think of this as just an average, we're putting in more low numbers into that set of numbers that we calculate the average, and these are due to preventable kinds of problems and consequences.
Benz: We often hear about increasing rates of longevity discussed as kind of a scary thing that programs like Social Security and Medicare are at risk of running out, that we won't have enough caregivers to assist our older population, and so on. Many of those issues we've discussed at length on the podcast previously, but you think that there are some positives associated with longevity. And I'm hoping you can talk about what some of those are.
Carstensen: I am frankly aghast when people say, "Oh, this is bad that we're living longer." And what this means is that we're not dying. That's not a bad thing. Just about any way you look at it, this is good. So, what our ancestors did in the 20th century was really reduce premature death. That was the accomplishment. And so now people are having a chance to live out their lives. Now, we were handed these 30 extra years of life in the 20th century with no strings attached. Our ancestors hand us more time, and more time is of course fabulous. It means more time to chase our dreams and realize our goals and spend with our loved ones. This is time. It's a great gift, and we should not forget that.
Where the problems originate is really now in this mismatch between the length of our lives and the culture that supports us and guides us through life. And in that culture are included behavioral practices--how we save, how we work, when we retire--but also programs like Social Security and Medicare, which were premised on an age distribution in the population that no longer exists. Those programs are premised on the idea, the assumption--which was a great assumption to make in the early 20th century--that you got a lot of young people and not very many old people. Well, then you can develop a policy based on that. And that's our problem today is that there's this mismatch between the policies and the demography.
It doesn't mean, however, that there isn't a way to live and there aren't policies that could be based on more rectangularized age distributions; it just means that we haven't done that yet. And so, there is a real urgency. There is a crisis on the horizon, by the way, if we do nothing, if we don't change the way we live, if we don't rethink these policies or practices, we're in trouble. But to say we're living too long, is to me putting the emphasis on the wrong problem. The problem is we aren't changing fast enough.