Today there are several lines of research under way that are treating both the infirmities of aging and the aging process itself, so that we are treating many of the phenomena like loss of memory, loss of vision, sexual performance, and so on with individual therapies, and in the course of that we are essentially extending the quality of life for people at a much higher age. If one then in addition looks at the current work on stem cells as well as on certain phenomon like telomerase, an enxyme in DNA, what we find is we are learning a great deal about how that mechanism is the control mechanism for aging, and it is very likely that over the next 25 years, we will be actually be able to manipulate the production of telomerase in individual cells. In other words, society will see serious and effective medical intervention in the aging process---people undergoing such therapy will keep looking and feeling and acting younger than their calendar age. The prospect to individuals for living seriously longer than the current norm will begin to open up.
The Hayflick limit is the limit of the maximum number of cell replications that a human being (or any species) can engage in. So, how many times do our cells replace themselves? That's the limit of human lifespan. When you can't replace your cells anymore, you die. And Leonard Hayflick calculated that number for a variety of species, and for human beings it was 120. So we have almost no documented instances of people living more than one hundred and twenty years.
Science and medicine will not only be essentially extending people to their normal full life span (i.e. 120), but will extend the human natural life span to beyond that, and a reasonable guess as to how much will be gained over the next century or so is at least 25 or 30 years. In other words, a person born in the year 2000 will still be alive in 2150 There's one other factor. If one simply looks at the historical trend, one finds that over the last century, we have nearly doubled human life span. The average lifespan of human beings (average, not maximum) has gone from about 45 to about 85. With the advances in microbiology and molecular biology, there's no reason to imagine that we won't do at least as much in the next century. In fact, if you double 85, you're at 170... so I'm actually being conservative.
Peter's bet blithely refers to overcoming the Hayflick Limit without even considering the bioethical or social implications of doing so. I suspect that it will be broken, like the atom. But this is one of the fundamental building blocks of evolution--what arrogance and self-importance to think that our existence is so important and valuable that we have the right to mess with evolution, or that we have any clue whatsoever as to the implications of doing so. There's a tremendous outcry about cloning, bypassing sexual reproduction, but no one seems to think there's a problem with cracking the code to immortality.
The life span-expiration mechanism came into play in evolution about the same time as the infinitely popular sexual reproduction. Unless done in by inclement circumstances, single cell animals such as yeast don't die; they just divide. Ironically, the arising of limited life spans coincided with and seemingly contributed to the rapid proliferation of life on Earth. My nonscientific, intuitive take on this is that evolutionary adaptation takes place more rapidly when the older generation gets out of the way, especially as organisms increase in complexity. Humans may succeed in overcoming self-limiting life spans but the result is likely to be contra-indicatory to the continued success of humans and other life.
Further, from a political and compassionate point of view, I am convinced that such an extension of life span would benefit only the privileged and powerful, as it already does. The desire of the self to continue existing is a nearly irresistible force. But it is one thing to extend life by optimizing the care and circumstances of the organism and quite another to extend it by neutralizing inherent cellular functions. I do not doubt that further advances will be made in prolonging longevity and perhaps Peter will prove correct. Luckily, there's yet another expiration barrier that comes into play at about 200 years of age. I am betting money against his prediction purely because I believe that the further radical prolonging of human (and pet) longevity would not benefit the human species, nor the other species who are also rightful inhabitants of this small planet.