(CN) — One of the most intriguing elements of our planet is the emergence of intelligent life with the capacity for complex analysis and development. But if history repeated itself intelligent life on Earth would not be guaranteed, according to a study published Monday.
Life on Earth blossomed into existence during the first quintile of millennia the planet became habitable enough to sustain it. But the rise of complex civilizations and human technologies only sprung up in the last quintile.
If any advanced space travelers from ages past searched for life on Earth in that first quintile, they might have sped away believing the planet would never contain intelligent life.
So how do we measure the development of intelligent life on Earth over time and how can those findings inform our search for life in the cosmos? Could contemporary stargazers observing what they believe is a desolate planet in fact be viewing a planet with the early signs of burgeoning intelligent life?
David Kipping, a researcher at Columbia University in New York City and author of the study, set out to answer some of those questions.
“A fundamental question to modern science concerns the prevalence of life, and intelligence, within the Universe,” Kipping wrote in his study. “Despite having no observational data concerning nonterrestrial life, we are in possession of stronger constraints when it comes to life on Earth. Until this situation changes, inferences concerning the existence of life elsewhere in the Universe must unfortunately rely heavily on this single data point.”
Kipping developed a statistical formula to understand the rate of abiogenesis — the spontaneous generation of living things on Earth — over time, and employed a Bayesian analysis to come to his conclusion.
The Bayesian method is a statistical device that allows researchers to create inferences about a population by combining past information about a population parameter with evidence from data sourced from a sample study.
The method, named for English mathematician Thomas Bayes, allowed Kipping to analyze the chronology of the rise of intelligent life on Earth.
Kipping posits that intelligent life emerged rapidly given life’s relatively quick start on Earth.
“The plausibility of the slow-start scenario can be understood to be a consequence of the selection effect, which requires that life emerges fast enough for us to have sufficient time to evolve into complex ‘intelligent’ organisms capable of observing ourselves,” the study says. “The early emergence of life on Earth then becomes consistent with a low abiogenesis rate, since worlds where life does not emerge quickly never evolve to the point of an intelligent observer.”
Kipping’s analysis shows that if the wheels of time were to reverse and then promptly run forward again, the emergence of intelligence would not be guaranteed to reoccur, according to the study published Monday in the journal of Proceedings of the National Academy of Sciences of the United States.
But the Bayesian formula also shows the rise of intelligent life on Earth would be a sufficiently rare event if Earth’s clock were to run again from the start.
“Employing objective Bayesianism and a uniform-rate process assumption, we use just the chronology of life’s appearance in the fossil record, that of ourselves, and Earth’s habitability window to infer the true underlying rates accounting for this subtle selection effect,” the study said. “Our results find betting odds of >3:1 that abiogenesis is indeed a rapid process versus a slow and rare scenario, but 3:2 odds that intelligence may be rare.”
While the emergence of intelligent life on Earth would not be guaranteed, life itself would still develop similarly early compared to when life emerged in reality on our planet, according to the study titled “An objective Bayesian analysis of life's early start and our late arrival.”
Kipping did not immediately respond to a request for comment on the study by press time.
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