"Despite what the fashion magazines tell you, 40 isn't the new 30," says Rachel Ehrenberg at Science News. "Seventy is." Thanks to advances in medicine, better sanitation, and other environmental changes, humans are living longer than ever before. In Japan, for example, a 72-year-old has the same likelihood of dying in one year as a 30-year-old hunter-gatherer did some 1.3 million years ago. Here, a concise guide to the new research backing these claims:

How was this study conducted?
A team of evolutionary anthropologists, led by Oskar Burger at the Max Planck Institute for Demographic Research in Germany, pored over mortality data from Sweden, France, and Japan. They also looked at death rates of present-day hunter-gathers and from wild chimpanzees to approximate unavailable mortality data from millions of years ago.

What did they find?
The probability of someone dying today at 72 is "similar to the death odds our ancestors likely faced at 30," says Ehrenberg. A 15-year-old hunter-gather, for example, had the same probability of dying within a year as a 69-year-old living in modern Sweden. (Unfortunately, data from the United States wasn't analyzed.) 

Why are we living longer?
"Improvements in our living conditions through medicine, better sanitation, and clean drinking water (considered 'environmental' changes) accelerated life spans to modern levels in just 100 years," says Trevor Stokes at LiveScience. Researchers think that while genetics play a "small role" in shaping human mortality, the key driver when it comes to living longer is "the advent of medical technologies, improved nutrition, higher education, better housing," and the like. It's for these reasons that the mortality rate fallen so rapidly in the past four generations. 

How much longer will we be living, then?
Mortality curves that show the probability of dying at a certain age are, right now, "at their lowest possible value," says Caleb Finch, a neurogerontology professor at the University of Southern California, who wasn't involved in the study. That means there's a "very strong prediction that life span cannot increase much more" than current rates. 

Sources: LiveScience, Science News, WHPTV