A new study suggests that humanity is hitting the upper limit of life expectancy. Advances in medical technology and genetic research are not translating into marked jumps in lifespan overall. That's according to researchers who found shrinking longevity increases in countries with the longest-living populations. The study was published online Monday by the journal Nature Aging. Experts say it’s likely that the number of centenarians will grow in the decades ahead, but that’s because of population growth.
