Do we have a planetary bias when it comes to understanding where life can perpetuate? It's only natural that we do. After all, we're on one.

However, planets may not be necessary for life, and a pair of scientists from Scotland and the USA are inviting us to reconsider the notion.

We focus on planets as habitats for life because they meet the conditions necessary for life to survive. Liquid water, the right temperature and pressure to keep it in a liquid state, and protection from harmful radiation are the primary requirements for photosynthetic life.

But what if other environments, even ones maintained by organisms themselves, can also provide these necessities?

In new research published in the journal Astrobiology, researchers point out that ecosystems could generate and sustain the conditions necessary for their own survival without requiring a planet.

The paper is titled "Self-Sustaining Living Habitats in Extraterrestrial Environments." The authors are Robin Wordsworth, Professor of Earth and Planetary Sciences at Harvard, and Charles Cockell, Professor of Astrobiology in the School of Physics and Astronomy at the University of Edinburgh.

"Standard definitions of habitability assume that life requires the presence of planetary gravity wells to stabilize liquid water and regulate surface temperature," they write. "Here the consequences of relaxing this assumption are evaluated."

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