When we talk about human evolution, we usually talk about how we evolved into humans: how we lost body hair, gained brain mass, started to walk on two feet—in short, things that happened millions of years ago.

But evolution did not stop when the first modern humans emerged. A new studyof two massive genetic databases—one in the United Kingdom and one in California—suggests genetic mutations that shorten lifespans have been weeded out since, and are possibly still in the process of being weeded out today.

The idea for the study, says Molly Przeworski, a geneticist at Columbia, came when the health-care company Kaiser Permanente decided to make available a massive genetic database of certain patients in California. Over lunch at the time, she and the study’s coauthor, Joseph Pickrell, did a quick back-of-the-envelope calculation: With a 100,000-person database, they could see evolution acting on a mutation found in more than 10 percent of the population.

Read the full article at The Atlantic

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Sarah Zhang is a staff writer at The Atlantic.