Life on Earth only has as little as 1.75 billion years left before it fizzles out, scientists predict.
But the planet could also come to an end in as many as 3.25 billion years, lead researcher Andrew Rushby, a graduate student at the University of East Anglia in Britain, forecast.
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In their research, Rushby and his team identified a 1.5 billion-year spread in which they say Earth will move out of the solar system's so-called "habitable zone" and into a "hot zone."
In this "hot zone," the Earth's oceans would evaporate, leaving no water source for humans to survive, Rushby wrote in a new paper published in the journal Astrobiology.
"Humans would be in trouble with even a small increase in temperature, and near the end only microbes in niche environments would be able to endure the heat," he told the Norwich Evening News last week.
The research team also looked at the lifespans of other planes in the habitable zone to see which ones might have potential for complex life. Rushby said intelligent life could emerge on one of those planets in the coming years, as it takes millions and even billions of years for cells and organisms to evolve.
"We had insects 400 million years ago, dinosaurs 300 million years ago, and flowering plants 130 million years ago," he told the Evening News. "Anatomically modern humans have only been around for the last 200,000 years — so you can see it takes a really long time for intelligent life to develop.
"Much of evolution is down to luck, so this isn’t concrete, but we know that complex, intelligent species like humans could not emerge after only a few million years."
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