You published two intriguing books, "Why we age, what science is discovering about the body's journey through life." And that book was translated into several languages, at least eight languages. Your new book, "Methuselah's Zoo: What nature can teach us about living longer" will be released in MIT Press this year. 

So let's start with a discussion with animals as model organisms for aging processes. How to make sense of the vast difference in the lifespans of animals? Dr. Steven Austad, PhD. Dr. Anton Titov, MD. 

Yes, so I think this is a very important point. And ever since I came into the aging research field, I've been very much concerned about which animals we use to study aging because if you think about it, virtually every animal ages, so almost any animal should be able to be a model of aging. But humans are different than most animals. We age more slowly than most animals. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. We are the longest-lived mammal that doesn't live in the ocean. And so the question becomes, what can we learn from other species that might help teach us something about human life? And my thought is that we want to look at species that age more slowly than we do. That's where the lessons from nature are going to be learned. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. 

You're right. There's a vast, vast difference between the shortest-lived and the longest-lived organisms. And initially, when I got into aging research, I wanted to try to understand that difference. Since I've been in the field long enough, I've decided, wait a second, this is not just an abstract question. This is something that humans are very, very concerned about, especially as the global population ages. And I've also been a little bit concerned that almost all biomedical research goes along with animals that are demonstrable failures at aging. That is, they fall apart very, very quickly, relative to us. Dr. Steven Austad, PhD. Dr. Anton Titov, MD. And I'm concerned that we're not going to learn what we need to know from studying worms and mice and flies.