If we’re alone in the universe, then the big question is: Why? There are billions upon billions of Earth-like planets out there. Surely, life would have evolved many times over. But lo, Jody Foster couldn’t find any back in 1997, and today, almost 20 years later, we’re still searching.

This conundrum is known as the Fermi Paradox, named after physicist Enrico Fermi, who famously asked “Where is everybody?” one day while eating lunch with his colleagues (note to self: nix the sad desk lunch; you’ll never get a paradox named after you this way), and scientists have been scratching their heads over it for decades. But in a new paper published this week in the journal Astrobiology, two researchers from the Australian National University propose a possible explanation.

They call it the Gaian Bottleneck, and it basically says this: Life did evolve all over the place a few billion years ago; it just all went extinct soon after due to runaway heating or cooling. We’re the exception, the researchers argue, because life on Earth evolved fast enough to start balancing greenhouse gases like H2O and CO2, thus preventing such runaway climate change. So in a way, life evolved here because life evolved here — try smokin’ a J and chewing on that for a while.