Charles Cockell argues that Earth may be a lonelier place than is popularly thought. This is despite recent discoveries of a plethora of distant solar systems and potentially habitable planets.
On Earth, living organisms fill just about every environment capable of supporting them.
This leaves the wrong impression that life is bound to arise anywhere it can, says Prof Cockell.
“The pervasive nature of life on Earth is leading us to make this assumption,” said the professor, who is director of the UK Centre for Astrobiology at the University of Edinburgh.
“On our planet, carbon leaches into most habitat space and provides energy for micro-organisms to live.
“There are only a few vacant habitats that may persist for any length of time on Earth, but we cannot assume that this is the case on other planets.”
Even though habitable planets might be abundant in the universe, that does not mean the same is true of Earth-like life, says the professor. More than 800 “extrasolar” planets orbiting stars beyond the Sun have been detected since the early 1990s.
Advanced techniques are now allowing astronomers to identify smaller, rocky planets within the “habitable” zones of their parent stars.
The habitable, or “Goldilocks”, zone is an orbital pathway just the right distance from a star to allow mild temperatures and surface water, a prerequisite for life as we know it.
In a talk at the Royal Society in London today, Prof Cockell warns against expecting too much from the search for extraterrestrial life.
“It is dangerous to assume life is common across the universe — it encourages people to think that not finding signs of life is a ‘failure’, when in fact it would tell us a lot about the origins of life,” he said.
Not assuming that life is “out there” would make it possible to approach the question in a more scientific way, the professor claims.
Even if another planet did harbour life, it might be so alien that we do not recognise it, he added.
Chemical signatures of life that could in future be detected by astronomers — such as oxygen or carbon dioxide — would be dependent on biology evolving the same way that it does on Earth, said Prof Cockell.
A completely different kind of life that did not have the same fingerprints could easily be missed.
Prof Cockell is one of a number of experts attending a discussion meeting at the Royal Society, entitled “Characterising exoplanets: Detection, formation, interiors, atmospheres and habitability”.