For years, scientists have studied the skin microbiome by analyzing DNA found on the surface of our skin. But there’s a big problem: that DNA doesn’t just come from living bacteria—it also comes from dead ones, long gone but still leaving traces behind.

A team of researchers decided to tackle this issue head-on. They used a clever method to remove what they call “relic DNA” — the leftover genetic material from dead microbes — and focused only on the DNA from live bacteria.

The result? Surprising: up to 90% of the DNA on our skin can come from dead microbes.

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