A new study rewrites the story of human evolution, suggesting that intelligent life is not rare but a natural planetary process rather than an improbable event.

“Our existence is probably not an evolutionary fluke,” says Jennifer Macalady, a study co-author and microbiology professor at Pennsylvania State University. “We’re an expected or predictable outcome of our planet’s evolution, just as any other intelligent life out there will be.”

If an extraterrestrial civilization existed with technology comparable to ours, would they be able to detect Earth?

Roughly 300,000 years ago, our species first appeared on the African landscape before spreading globally and coming to dominate the planet. All this happened about 4.5 billion years after Earth formed,