Thursday, December 1, 2022

Q&A with Steven N. Austad




Steven N. Austad is the author of the new book Methuselah's Zoo: What Nature Can Teach Us About Living Longer, Healthier Lives. His other books include Why We Age. He is Distinguished Professor of Biology at the University of Alabama at Birmingham.


Q: What inspired you to write Methuselah's Zoo, and what first intrigued you about studying longevity? 


A: I began thinking about the longevity of various species years ago, when I discovered by accident that opossums lived only about two years in nature. That was shockingly short. Moreover, they seemed to fall apart physically almost overnight. They lost muscle, became frail and parasite-ridden, got cataracts, all within a few months.


I had always assumed that you could estimate how long something lived from how big it was. We all know that dogs live longer than mice, horses longer than dogs, elephants longer than horses. So I assumed that opossums, which are about the size of house cats, would live 10-20 years.


I was so struck by this observation that virtually ever since I have been compiling information on how long various species lived. After decades of doing this, I realized that I knew more than anyone else on the topic and thought that people with an interest in animals would have an interest in species with exceptional longevity and their natural history.


Although my original intuition about size turns out to be generally true – bigger species do generally live longer than smaller species – there are dramatic exceptions and I think those exceptions give us insight into why we age and whether we might be able to modify our own aging rate.


Getting back to size, here are three species that are all about the same size but live dramatically different lengths of time: opossums: two to three years, house cats: up to 20 years or so. Albatrosses up to 70 years or so. Flight, it turns out, is associated with exceptional longevity.


Q: What would you say are some of the most common perceptions and misconceptions about the aging process?


A: Misconception #1 is probably how important genetics is to aging and longevity. People think that how long their parents live pretty much determines how long (and how well) they are likely to live.


Lots of research shows that ancestry determines only about 20-25 percent to how long you can expect to live. The other 75-80 percent is environmental, meaning that you have a lot of control, by your lifestyle habits, over how long you will live and be healthy.


Misconception #2 is likely that in the distant past people aged much more quickly than we do today. It is true that in the distant past, average longevity was much shorter. Before we know about proper hygiene and germs or had developed childhood vaccinations, death could come quickly to just about anyone if they were in the wrong place at the wrong time.


Infections were ubiquitous. One-third of children died before age 10. But a healthy 40 or 60 year old 2,000 years ago would have been pretty much the same as a healthy 40 or 60 year old today. The difference is that many fewer people reach 40 or 60 years of age then than now.


And exceptionally old people have always been with us. The ancient Egyptians 5,000 years ago considered 110 years to be about the limit of human life. Today we think that limit may be a bit over 120 years – not such a big difference.


Q: You describe a wide range of creatures in the book. Do you have a particular favorite, or one that especially fascinated you?


A: Yes. I have an inordinate fondness for bats. When I worked as a field biologist in South America, I was around bats all the time and found them endlessly fascinating. That was before I had any idea how long they lived.


We saw bats in our house, in the forest every night of course. I caught bats by accident in mist nets I had set to catch the birds I was researching. I probably handled 30 or more bat species when removing them from my nets and releasing them back into the forest. We even had bats in the local movie house where they put on quite the show.


The light beam from the movie projector would attract moths, bats of course were attracted to the moths, and the shadows of bat-moth chases showed up on the move screen, providing much more entertainment that the movies that were typically shown.


Then I discovered that these little creatures, a fraction as large as a mouse, could live 20, 30, even 40 years in the wild where just about everything was out to get them. To maintain the endurance and agility to catch insects on the wing in the dark, fly 50 miles or more per night, and find your way home, again in the dark, astonished me.


Even the fact that some bats, the longest-lived ones, could remain inactive for months when hibernating, then wake up and fly away amazed me, particularly when we all know that a week or so of inactivity in the hospital makes it difficult for people just to get out of bed and walk. How they do all these things has something to teach us about our own aging,in my opinion.


Q: In the book, you describe a wager you made about human longevity. Can you explain why you made that wager, and what you see looking ahead when it comes to longevity?


A: Sure. In 2001 I made a wager with demographer S. Jay Olshansky about when we would have a legitimate 150-year-old person. I said that I thought that person was already alive.


The oldest person known at the time, and still the oldest person with validated birth and death dates, lived 122 and a half years, so I was betting that advances in the scientific understanding of aging would lead to our being able to learn how to medically slow the rate of aging by at least 20 percent, which is roughly the difference between 122 and 150 years, in time for someone to become 150 years old by the year 2150.


Olshansky was equally convinced this would not happen. So we each put $150 into an investment account and calculated that at the historical rate of growth in the stock market that $300 would grow to $500,000,000 by 2150.


At that time, if there was at least one 150 year old alive and cognitively intact enough to carry on a conversation, my descendants (or in the best case I) would get the accumulated money. If not, his descendants would get it.


By the way, some 20+ years on, we are still both convinced we are right. A few years back, we doubled the bet, so that it would be projected to be worth a cool $1 billion by 2150.


Q: What are you working on now?

A: I have gotten very interested in differences between men and women in aging and longevity. As everyone knows, women live longer than men, although I doubt that many know that women have always lived longer. They live longer everywhere and in all historical epochs for which we have reliable birth and death records.


Even as babies, girl babies survive better than boy babies. Women survive better during famine, during pandemics, during just about any hardship. I’d like to understand that and am working on that question now.


There is a paradox here though. Although women live longer, in later life they tend to be in worse health. They are more likely than men to be disabled, more likely to become demented, spend more time in the hospital. This is true even correcting for the fact that they live longer.


If we could find a way to allow men to survive as long as women, and for women to remain healthy as long as men, we would be making a great contribution to human health and happiness.


Q: Anything else we should know?


A: Everything else that you need to know can be found in my book, of course. But I do want to point out how staying physically and mentally active (say, by reading books) are about the best thing you can do for your physical and mental health.


--Interview with Deborah Kalb

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