Darwinian evolutionary theory will help find alien life

In a talk marking the 150th anniversary of the publication of On the Origin of Species, a Nasa scientist said that Darwinian evolution will be the driving force of life anywhere in the universe, and we should use its predictions to decide where to look.

Dr John Baross, a researcher at the Nasa Astrobiology Institute, said: "I really feel that Darwinian evolution is a defining feature of all life.

"And so the limits of Darwinian evolution will define the range of planets that can support life – at least Earth-like life."

Speaking at a public lecture at the Nasa Ames Research Center in Mountain View, California, Dr Baross said that the Kepler Space Telescope’s mission, looking for Earth-like planets around other stars, made this an exciting time for astrobiology – the search for alien life.

He said: "I predict in the next five to ten years, we will make discoveries that will lead to theories and ideas at least as profound as Darwin's."

Dr Baross said that looking for alien life has always involved using the Earth as a model. While our understanding of how life began is incomplete, it seems clear that there are certain requirements.

All life on Earth needs water, carbon-based organic molecules, and an energy source, either solar or chemical. But alien life may not be entirely Earth-like. Dr Baross said: "I'd like to point out there are many different ways for non-Earth-like life to not use light or chemical energy but use some other form like radiation energy, wave energy, or ultraviolet energy."

Similarly, the need for water may not be universal. Dr Baross said: "[Life may exist] in an organic solvent rather than liquid water on Titan, or… at temperatures of minus 100 degrees Celsius — there are a lot of ways to think of this because those conditions exist on other planetary bodies."

So far, astronomers have found 403 “exoplanets” – planets outside our own solar system. While most of them are Jupiter-like gas giants hundreds or thousands of times bigger than the Earth, a few smaller ones have been found, and Kepler is expected to start finding many more over the next few years.

"I think all of us really believe that rocky planets, like Earth, are going to be found at some point,"