Humans could well be alone in the observable universe, a statistical study has suggested.
The evolution of intelligent life is a wildly improbable fluke, research by Oxford University’s Future of Humanity Institute showed.
The researchers said that the unlikeliness of the series of “evolutionary transitions” that led to intelligent life means it is likely to be “exceptionally rare”.
They believe that there is between a 53% and 96% chance that humans are alone in our Milky Way galaxy, Discover magazine reported.
Aliens may have once existed, but could already have been wiped out, the researchers said.
Anders Sandberg, of the Future of Humanity Institute, said: “An empty sky doesn’t mean we are doomed.”
Watch: Astronomers search 10 million stars with no sign of aliens
The researchers wrote: “It took approximately 4.5 billion years for a series of evolutionary transitions resulting in intelligent life to unfold on Earth.
“In another billion years, the increasing luminosity of the Sun will make Earth uninhabitable for complex life. Intelligence therefore emerged late in Earth’s lifetime.”
The sheer timescale required for life to evolve means it’s far less probable that life flourishes elsewhere, the researchers said.
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“One can conclude that the expected transition times likely exceed the lifetime of Earth, perhaps by many orders of magnitude,” the study said. “In turn, this suggests that intelligent life is likely to be exceptionally rare.”
The researchers pointed out that some of the steps required to achieve intelligent life appear to be far less likely than others.
“The fact that eukaryotic life took over a billion years to emerge from prokaryotic precursors suggests it is a far less probable event than the development of multicellular life, which is thought to have originated independently over 40 times.”
Research earlier this year made it seem a little more likely that humanity might be all alone in the universe after a scan of 10 million stars found not a whisper of alien life.
A scan using a radio telescope in the Australian outback conducted a deep and broad search for alien communications at radio frequency.
Focusing on a patch of sky known to contain at least 10 million stars, the researchers used the Murchison Widefield Array (MWA) telescope to scan – and found nothing.
Dr Chenoa Tremblay, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the telescope was searching for powerful radio emissions at frequencies similar to those emitted by FM radio.
These possible emissions are known as ‘technosignatures’, Dr Tremlay said.
“The MWA is a unique telescope, with an extraordinarily wide field-of-view that allows us to observe millions of stars simultaneously.
“We observed the sky around the constellation of Vela for 17 hours, looking more than 100 times broader and deeper than ever before.
“With this dataset we found no technosignatures – no sign of intelligent life.”
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