Humanity may not be something extraordinary but rather the natural evolutionary result of our planet and probably of others.
This is raised by a new work led by experts from the Univesity of Pennsylvania State. Specifically, the study raises a new model of how intelligent life was developed on Earth, as described in the magazine ‘Science Advances’.
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The model, which Put by land The theory of “difficult steps“That dates back decades and claimed that Smart life was an incredibly unlikely event, He suggests that perhaps it was not so difficult or unlikely. The Penn State Researchers team clarifies that the new interpretation of the origin of humanity increases the probability that there is intelligent life in other parts of the universe.
“This is a significant change in our way of thinking about the history of life”Jennifer Macalady, a geo -science professor at Penn State and co -author of the article. “It suggests that the evolution of complex life can have less to do with luck and more with the interaction between life and its environment, opening new and exciting ways of research in our search to understand our origins and our place in the universe”.
Initially developed by the theoretical physicist Brandon Carter in 1983, the “difficult steps” model argues that our evolutionary origin was highly unlikely due to the time it took to humans evolving on earth in relation to the total useful life of the sun and,, Therefore, the probability that there are beings similar to humans beyond earth is extremely low.
In the new study, the team of researchers who included astrophysicists and geobiologists argued that the environment of the Earth was initially inhospitable for many life forms and that the key evolutionary steps were only possible when the global environment reached a state “permissive”.
For example, complex animal life requires a certain level of oxygen in the atmosphere, so the oxygenation of the atmosphere of the Earth through microbes and photosynthetizer bacteria was a natural evolutionary step for the planet, which created a window of opportunity To develop more recent ways of life, explains Dan Mills, postdoctoral researcher at the University of Munich (Germany) and main author of the article.
“We are arguing that intelligent life may not require a series of hits of luck to exist”clarifies Mills, who worked in the Macalady Astrobiology Laboratory in Penn State as undergraduate researcher. “Humans did not evolve ‘early’ or ‘late’ in the history of the earth, but ‘on time’, when the conditions were given. Maybe it’s just a matter of time, and maybe other planets are able to achieve these conditions faster than Earth, while other planets could take even more ”.
The central prediction of the theory of “difficult steps” establishes that there are very few civilizations, if there is any, throughout the universe, because steps such as the origin of life, the development of complex cells and the emergence of intelligence Human are unlikely according to Carter’s interpretation that the total useful life of the sun is 10,000 million years and the age of the land of around 5,000 million years.
In the new study, the researchers proposed that the time of human origin can be explained by the sequential opening of “habitability windows” throughout the history of the earthdriven by changes in nutrient availability, sea surface temperature, ocean salinity levels and the amount of oxygen in the atmosphere. Given all interrelated factors, they argue, the land has only recently become hospitable for humanity; It is simply the natural result of these conditions in operation.
“Instead of baseing our predictions on the useful life of the sun, we consider that we should use a geological time scale, because that is the time they take to change the atmosphere and landscape”points out Jason Wright, professor of astronomy and astrophysics at Penn State and co -author of the article. “These are normal time scales on Earth. If life evolves with the planet, then it will evolve in a planetary time scale at a planetary pace ”.
Wright explains that part of the reason why the “hard steps” model has prevailed for so long is that it originated in its own discipline, astrophysics, which is the default field that is used to understand the formation of planets and celestial systems. The team’s article is a collaboration between physicists and geobiologists, each learning from the fields of the other to develop a nuanced image of how life evolves on a planet like Earth.
“This article is the most generous act of interdisciplinary work”points Macalady, who also directs the Astrobiology Research Center of Penn State. “Our fields were very remote and put them on the same page to get to this question of how we got here and if we are alone. There was an abyss and we built a bridge “.
Researchers plan to test their alternative model, which includes questioning the unique character of the proposed evolutionary “steps”. Recommended research projects are described in the current document and include works such as the search for biofirmas, such as the presence of oxygen, in planet atmospheres outside our solar system. The team also proposes to test the requirements of the “hard steps” proposed to determine how hard are really through the study of unicellular and multicellular life forms in specific environmental conditions, such as lower levels of oxygen and temperature.
Beyond the proposed projects, the team suggests that the scientific community should investigate whether innovations – such as the origin of life, oxygenic photosynthesis, eukaryotic cells, animal multicellularity and homo sapiens – are truly unique events in history in history From Earth. “This new perspective suggests that the appearance of intelligent life may not be such a remote possibility after all”plantea Wright. “Instead of a series of unlikely events, evolution can be a more predictable process, which is developed as global conditions allow. Our frame applies not only to Earth, but also to other planets, which increases the possibility that there may be life similar to ours in other places ”.