A new paper shows that the evolution of intelligent life is ‘exceptionally rare’. It thus concludes that it is very unlikely that human-like civilisations exist on other planets.
It would indeed take longer than the whole of Earth’s projected lifespan for life to evolve in the same way elsewhere in the universe.
Yes! What’s happened on Earth is unlikely typical of what happens on other planets
The earthy evolutionary transitions were helped by chance, like the emergence of primitive life from non-living matter and eukaryotic life, the evolution of sexual reproduction, multicellularity, and intelligence itself.
If intelligent life does exist on other planets, it would need to have gone through a series of comparable evolutionary transitions.
The new paper draws on the Fermi paradox, the apparent contradiction between the lack of evidence for extra-terrestrial civilizations and various high estimates for their probability.
‘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. Together with the dispersed timing of key evolutionary transitions and plausible priors, one can conclude that the expected transition times likely exceed the lifetime of Earth, perhaps by many orders of magnitude. In turn, this suggests that intelligent life is likely to be exceptionally rare.‘
The new data are based on statistics and on the ‘tricky’ assumption that what happened on Earth is typical for what happens on other planets – not the exact times, but that there are some tricky steps life needs to get through in sequence to produce intelligent observers.
What is the Fermi Paradox?
The Fermi Paradox, named after its creator E. Fermi, questions why, given the estimated 200bn-400bn stars and at least 100bn planets in our galaxy, there have been no signs of alien life.
Fermi believed it was too extraordinary that a single extraterrestrial signal or engineering project has yet to be detected in the universe — despite its immense vastness.
Fermi concluded there must a barrier that limits the rise of intelligent, self-aware, technologically advanced space-colonising civilisations.
This barrier is sometimes referred to as the ‘Great Filter’.
If the main obstacle preventing the colonisation of other planets is not in our past, then the barrier that will stop humanity’s prospects of reaching other worlds must lie in our future, scientists have theorised.
Professor Brian Cox believes the advances in science and engineering required by a civilisation to start conquering the stars ultimately lead to its destruction.
He said: ‘One solution to the Fermi paradox is that it is not possible to run a world that has the power to destroy itself and that needs global collaborative solutions to prevent that.
‘It may be that the growth of science and engineering inevitably outstrips the development of political expertise, leading to disaster.‘
Other possible explanations for the Fermi Paradox include that no other intelligent species have arisen in the universe, intelligent alien species are out there — but lack the necessary technology to communicate with Earth.
Some believe that the distances between intelligent civilsations are too great to allow any kind of two-way communication.
If two worlds are separated by several thousand light-years, it’s possible that one or both civilisation will be extinct before a dialogue can be established.
The so-called Zoo hypothesis claims intelligent alien life is out there, but deliberately avoids any contact with life on Earth to allow its natural evolution.
Well I don’t think this is right! We are surrounded by habitable worlds. The aliens are out there and already on Earth. It’s just that they had different evolutive steps!
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