Bill Gifford in Scientific American:
How long can human beings live? Although life expectancy has increased significantly over the past century, thanks largely to improved sanitation and medicine, research into hunter-gatherer populations suggests that individuals who escaped disease and violent deaths could live to about their seventh or eighth decade. This means our typical human life span may be static: around 70 years, with an extra decade or so for advanced medical care and cautious behavior. Some geneticists believe a hard limit of of around 115 years is essentially programmed into our genome by evolution. Other scientists in the fast-moving field of aging research, or geroscience, think we can live much longer. A handful of compounds have been shown to lengthen the life spans of laboratory animals slightly, yet some scientists are more ambitious—a lot more ambitious.
João Pedro de Magalhães, a professor of molecular biogerontology at the Institute of Inflammation and Ageing at the University of Birmingham in England, thinks humans could live for 1,000 years. He has scrutinized the genomes of very long-lived animals such as the bowhead whale (which can reach 200 years) and the naked mole rat. His surprising conclusion: if we eliminated aging at the cellular level, humans could live for a millennium—and potentially as long as 20,000 years.
More here.