Trying to understand where life might evolve in other solar systems sometimes feels like we’re jumping ahead. We still don’t know what worlds in our solar system do, don’t, and previously had life. This won’t stop us from imaging other solar systems, but it does put a bit of extra push into the work of folks trying to understand just where life on Earth originated and when it originated.

Our planet’s oldest fossils date back to 3.5 billion years ago, and finding older rock is challenging, so this isn’t as much a “life wasn’t here before that” as “our world didn’t leave us a lot of rock we can access from before that”. There are some indications of biological activity just over four billion years ago, but that’s all we’ve got.

And our ability to better understand how planets form and evolve is starting to inform how we look for life. New interdisciplinary work brings together geologists and prebiotic chemists to work together on understanding all the various possible ways life could emerge. Under consideration are environments like the interface between rock and water and factored in are everything from the ultraviolet radiation of our young Sun and the delivery of organic molecules on impacting meteors and comets.

Researchers are taking into consideration how the materials released from the planet’s interior in volcanoes can rain down and interact with water in hot springs and the general water cycle. And researchers are imagining how life may not have started under the Sun but may instead have originated in the bottom of the ocean.

This is all to say that we don’t know how life came to exist; we just know it did, and through interdisciplinary collaborations, we’re constantly defining more places that it could have come into existence. And for now, we can be excited at the possibilities of life emerging in more than one of these places and continue to hope that it emerged on more than one world not just in our galaxy but maybe even in our solar system.

And while we figure this out, we’re going to keep dreaming of visiting other worlds.

More Information

Rethinking the Search for the Origins of Life (Eos)