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The Aliens Are Already Extinct

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Life on other planets would likely be brief and become extinct very quickly, according to astrobiologists from The Australian National University who argue that new life would commonly die out due to runaway heating or cooling on their fledgling planets.

“The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens,” said Dr Aditya Chopra, who is lead author of the research published in Astrobiology (

“Early life is fragile, so we believe it rarely evolves quickly enough to survive,” he said. “Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases, such as water and carbon dioxide, to keep surface temperatures stable.”

About four billion years ago Earth, Venus and Mars may have all been habitable. However, a billion years or so after their formation, Venus turned into a hothouse and Mars froze into an icebox.

Any early microbial life on Venus and Mars failed to stabilise the rapidly changing environment, said co-author A/Prof Charley Lineweaver. “Life on Earth probably played a leading role in stabilising the planet’s climate,” he said.

Chopra said their theory solved a puzzle. “The mystery of why we haven’t yet found...

The full text of this article can be purchased from Informit.