Here is another article in a popular science series on the history of human longevity and related topics. This looks at a mainstream disagreement in aging research, among researchers who do not see radical life extension as a near-term possibility:
One of the most fascinating debates in life science these days is between S. Jay Olshansky and James Vaupel of the Max Planck Institute for Demographic Research in Rostock, Germany. They disagree fundamentally about whether and how average life expectancy will increase in the future, and they've been arguing about it for 20 years. Olshansky, a lovely guy, takes what at first sounds like the pessimistic view. He says the public health measures that raised life expectancy so dramatically from the late 1800s to today have done about as much as they can. We now have a much older population, dying of age-related diseases, and any improvements in treatment will add only incrementally to average life expectancy, and with vanishing returns.
On the other side of the ring is Vaupel, who says that people are living longer and healthier lives all the time and there is no necessary end in sight. His message is cheerier, but he takes the debate very seriously; he won't attend conferences where Olshansky is present. His charts are heartening; he takes the records of the longest-lived people in the longest-lived countries for each year and shows that maximum lifespan has been zooming up linearly from 1800 to today. One wants to mentally extend the line into all of our foreseeable futures.
Olshansky says the only way to make major improvements in life expectancy is to find new ways to prevent and treat the diseases of aging. And the most efficient way to do that is to delay the process of aging itself. That's something that some people already do - somehow. Olshansky says, "The study of the genetics of long-lived people, I think, is going to be the breakthrough technology." Scientists can now easily extend lifespan in flies, worms, and mice, and there's a lot of exciting research on genetic pathways in humans that might slow down the aging process and presumably protect us from the age-related diseases that kill most people today. "The secret to longer lives is contained in our own genomes," Olshansky says.
Olshansky favors the mainstream high level research strategy that I believe is largely futile: a slow, expensive process of building treatments to alter human metabolism to look more like that of long-lived people, or replicate the effects of calorie restriction. It will produce a great deal of knowledge, but little effect on life spans: this is an approach that will slow aging slightly, not create rejuvenation, and not directly address the root causes of aging. If we want to see real progress in human life span in our lifetimes, decades or more of healthy life added even for those already old, then we have to back repair-based research such as the Strategies for Engineered Negligible Senescence (SENS).