We are not alone in studying odds

According to the new way of intelligent life developing on Earth, humans may not be extraordinary, but the natural evolution of our planet and others.

The model subverts the decades-old “hard steps” theory that smart life is an extremely unlikely event, suggesting that perhaps it is not that difficult or impossible. A team of researchers at Penn State who led the work said new explanations of human origins increase the possibility of smart living elsewhere in the universe.

“This is a major shift in how we view life history,” said Jennifer Macalady, a professor of earth sciences in Pennsylvania. Science Advances. “This suggests that the evolution of complex life may no longer be luck, but more information about the interaction between life and the environment, opening up exciting things for us to seek to understand our origins and our place in the universe. New research approach.”

Originally developed by theoretical physicist Brandon Carter in 1983, the “hard step” model argues that due to the time it takes for humans to live with respect to the total lifespan of the sun, our evolutionary origin is extremely unlikely. It is highly impossible, so humans outside the earth are like humans.

In the new study, a team of researchers, including astrophysicists and geobiologists, believes that the Earth’s environment is initially impossible for many forms of life, and only when the global environment reaches a “loose” state This critical evolutionary step is only possible.

For example, complex animal life requires a certain level of oxygen in the atmosphere, so oxygenation of the Earth’s atmosphere by photosynthesis by microorganisms and bacteria is a natural evolutionary step for the planet, creating a window of opportunity for recent forms of life , to enable the development of life forms in the near future, to develop, and to develop forms. Dan Mills, a postdoctoral researcher and lead author at the University of Munich, explained.

“We think that a smart life might not require a series of lucky breaks,” Mills said, working in the astronomy lab at Macalady at Penn State University. “Humans did not evolve in the history of Earth’s ‘early’ or ‘late’, but ‘on-time’, when conditions were in place. Maybe it was just a matter of time, maybe other planets could reach these conditions faster than Earth, and other planets could It takes longer.”

The core prediction of the “hard step” theory points out that in the entire universe, few other civilizations exist because steps based on Carter’s life, the origin of complex cells, the development of complex cells and the emergence of human intelligence are impossible. The total lifespan of the sun is explained as 10 billion years, and the age of the earth is about 5 billion years.

In the new study, researchers suggest that the timing of human origin can be explained by the order in which “habitable windows” driven by changes in nutrient availability, sea surface temperature, ocean salinity levels and oxygen volumes are open in the history of the earth. In the atmosphere. They say that the Earth has not been hospitality to humanity until recently, given all the factors of interaction – this is just a natural result of these conditions at work.

“We think we should use geological time scales, not based on the lifetime of the sun, because that’s how long it takes for the whole atmosphere and landscape,” said astronomy professor Jason Wright. and Penn State University’s co-author of astrophysics and paper. “These are normal time scales on Earth. If life evolves as the planet develops, it will develop at the planetary time scale of the planet’s speed.”

Wright explains that the “hard step” model has been prevalent for so long in part because it originated from his own discipline of astrophysics, which is the default field used to understand the formation of planets and celestial systems. The team’s paper is a collaboration between physicists and geobiologists, each learning from each other’s fields to form a nuanced description of how life evolved on Earth like Earth.

“This article is the most generous act of interdisciplinary work,” he also directs Makaladi of Penn State’s Center for Astronomy Research. “Our fields are far apart, we put them on the same page to solve the problem of how we get here, are we alone? There is a bay and we build a bridge.”

The researchers said they plan to test their alternative models, including questioning the unique status of a proposed evolutionary “hard steps.” Recommended research projects are outlined in the current paper, which include, for example, the search for biosignatures in the atmosphere of planets outside the solar system, such as the presence of oxygen. The team also put forward requirements for the proposed “hard steps” to determine the practical difficulties of studying single and multicellular forms of life under specific environmental conditions such as lower oxygen and temperature levels.

In addition to the proposed project, the team also suggests that the research community should investigate innovations (such as the origin of life, the origin of oxygenation photosynthesis), eukaryotic cells, animal polycellularity and Homo sapiens – It is a truly strange event in the history of the earth. In the past, similar innovations were able to develop independently, but evidence that the evidence they occurred was lost due to extinction or other factors?

“This new perspective suggests that the emergence of smart life may not be a long shot after all,” Wright said. “Instead of a series of impossible events, evolution may be more like a predictable process with global conditions.” Unfolds as allowed. Our framework applies not only to Earth, but to other planets, thus increasing the possibility that life similar to ours might exist.”

Another co-author on the paper is Adam Frank of the University of Rochester. The Penn State University Center for Astronomy Research, Pennsylvania Exoplanets and the Livable World, Penn State Alien Intelligence Center, NASA Exobiology Program, and the German Research Foundation support this work.