Humanity has long questioned whether intelligent life is a rare cosmic accident or an inevitable result of planetary evolution. A new study now challenges the “difficult steps theory”: the idea that life came about by chance.
During the last decades, scientists have debated the likelihood of intelligent beings in other parts of the universe.
Some argue that our existence depended on a series of Almost impossible stepsmaking the existence of similar beings beyond the earth unlikely.
Others suggest that Evolution follows predictable standardswhich means that life like ours can be common in other planets.
One of Penn State investigators, published last week in the magazine Science Advancesnow challenges the idea that intelligence is unlikely chance.
The model developed by the researchers suggests that life evolves as the planetary conditions changemaking intelligence less a matter of luck and Another issue of opportunity.
The results of the study reformulate the discussion about our origins and the probability of discovering extraterrestrial civilizations.
For years, the dominant theory to explain the rarity of intelligent life was the Model of “Difficult Steps“.
Proposed for the first time by the physicist Brandon Carter In 1983, this idea suggests that the progression of the life of simple organisms for intelligent beings required multiple extremely difficult evolutionary steps.
The model proposed by Carter departs from the principle that, as needed thousands of millions of years for humans to appear On earth, the likelihood of intelligent life in other places should be extremely low.
However, The new study challenges this assumption. Investigators argue that The earth’s environment was initially inhospitable for complex life and that evolutionary advances occurred when conditions became adequate.
This suggests that Intelligence may not be the result of rare luckbut one Natural result of planetary development.
“This is a significant change in the way we think about the history of life,” explains Jennifer MacaladyGeoscience Professor at Penn State and co-author of the study, quoted by.
“The results of our study suggest that the evolution of complex life may have less to do with luck and more interaction between life and its environmentopening new and exciting research roads in our pursuit of understanding our origins and our place in the universe, ”details Macalady.
The role of environmental conditions
The new model proposes that the main evolutionary transitions, such as the appearance of complex cells and multicellular life, were essentially possible Gradual changes in the atmosphere and oceans from the earth.
Life has not evolved at random, but in response to changes in environmental factors, such as oxygen levels, ocean temperature and chemistry.
For example, Complex animals need oxygen enough to survive. The earth’s atmosphere has become rich in oxygen Due to the activities of microbes and photosynthetic bacteria, which created the appropriate conditions for the most advanced life.
“We are to argue that Intelligent life may not need luck To exist, ”he says And Millspostdoctoral researcher at the University of Munich and first author of the study.
Thus, the authors of the study support, human beings did not evolve “early” or “afternoon” in the history of the earth, but “in the right time” – When the conditions were gathered.
“Maybe it’s just a matter of timeand perhaps other planets can reach these conditions faster than Earth, while other planets can take even longer, ”explains Mills.
A different perspective from time
The “difficult steps” model is based on the assumption that evolution must be measured according to the sun’s lifetime.
With the sun lasting about 10 billion years and the land has been 5 billion years old, Carter suggested that intelligent life It must be extremely raresince appeared relatively late.
The new study adopts a different approach.
Instead of measuring evolution due to the sun’s lifetime, researchers suggest that a geological time scale: Evolution follows the planetary changes and not the arbitrary tick of a cosmic clock.
“We think, instead of based on our sunshine predictions, we must use a geological time scale, because this is the time that the atmosphere and the landscape are slow to change,” says Jason Wight, a teacher of astronomy and astrophysics at Penn State and co-author of the study.
“These are normal scales on Earth. If life evolves with the planet, then it will evolve on a planetary time scale to a planetary rhythm. ”
One of the reasons why the “difficult steps” model remained dominant for so long astrophysical origin. Astrophysics has traditionally shaped how scientists think about the formation of planets and the conditions necessary for life.
However, Evolution is a biological process Influenced by planetary chemistry, ocean currents and atmospheric changes.
To create their new model, the research team combined knowledge of Astrophysics, Geobiology and Planetary Sciences – An interdisciplinary approach that has allowed them to challenge longtime assumptions and present a broader view of how life evolves.
“Our fields were very distant and put them on the same page to answer the question of how we have come here and if we are alone. There was a pit and We built a bridge“, diz Macalady.
The study presents an hopeful vision of the potential of life beyond the earth. If intelligence arises naturally when planetary conditions are aligning, so the universe may be full of civilizations at different stages of development.
“This new perspective suggests that the appearance of intelligent life may not be, after all, such a remote hypothesis,” concludes Wright.
