Given the seeming paucity of moisture in the leftover remains of Earth's building blocks, planetary scientists have long assumed our planet's water supply came after it formed in a rain of hydrogen-soaked rocks and comets.

Researchers say they discovered evidence that early Earth was home to more hydrogen than previously thought, calling into question widely held beliefs about the origins of water and the planet’s evolution.

All that said, the findings can’t confirm the terrestrial life theory beyond a doubt. There’s still a chance hydrogen-heavy meteorites helped us along. Still, the new evidence makes a strong case that ancient Earth had the ability to form water all on its own—no space rocks needed.