Source: Physicsworld

Just because life emerged early on Earth does not mean that this is likely to occur on other Earth-like planets, says a pair of US astrophysicists. The researchers’ new mathematical model says that life could just as easily be rare – putting a damper on the excitement surrounding the recent discovery of Earth-like planets orbiting stars other than the Sun.

Estimates of the prevalence of life in the universe suffer from a severe lack of data. Indeed, they only have one data point – Earth – to support them. We are not even certain about whether our nearest neighbour, Mars, ever hosted colonies of microbes. Still, going on the Earth alone, it appears that life arose within a few hundred million years after the seething magma settled into a habitable planet. That seems early, considering that life then evolved for something like 3.8 billion years and looks likely to continue until the Sun balloons into a red giant about around five billion years from now.

“The rapid appearance of life on Earth is probably the best data we have to constrain the probability of life existing elsewhere in the universe, so it deserves to be squeezed as much as possible,” says Charley Lineweaver, an astrophysicist at the Australian National University.

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