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Yahoo
04-03-2025
- Science
- Yahoo
Intelligent life may be more common than we thought
When you buy through links on our articles, Future and its syndication partners may earn a commission. The evolution of humans on Earth may not be entirely exceptional. That is because intelligent life is likely to form if certain planetary conditions are met, a new study suggests. This idea displaces the previously-held belief that humanity's appearance occurred thanks to a highly improbable series of events. For a long time, scientists believed that human life on Earth only came about by chance, and therefore the formation of intelligent life in other places would be equally far-fetched. However, a new paper published in the journal Science Advances found that there were no "hard steps" required for humans to evolve and that life is likely to have formed elsewhere in the universe as well. "Homo sapiens and analogous extraterrestrial life forms may be the probable end result of biological and planetary evolution when a planet has a certain set of attributes that make it habitable, rather than requiring countless lucky breaks," said Reuters. The theory that intelligent life forming on Earth was an incredible occurrence first originated in a 1983 paper by Australian physicist Brandon Carter, which said that the "evolutionary chain included at least one but probably not more than two links that were highly improbable (a priori) in the available time interval." Carter posited that because it took so long for human life to form on Earth, it must be difficult, making the existence of humans entirely a fluke. But this new study identified a fallacy in Carter's reasoning. Carter "specifically assumed that the age of the sun, and therefore the Earth, should have no bearing on how quickly complex life evolved," said Researchers now say that is not true. "Life might have originated very quickly once temperatures were appropriate for the stability of biomolecules and liquid water," said Jennifer Macalady, a study co-author and microbiology professor at Pennsylvania State University, to Reuters. "The Earth has only been habitable for humans since the second rise of oxygen in the atmosphere approximately 0.5 billion years ago, meaning that humans could not have evolved on Earth prior to that relatively recent moment." Essentially, life on Earth evolved exactly when it was supposed to. While this is not direct proof of the existence of aliens, it does mean "our existence is probably not an evolutionary fluke," Macalady said to Popular Science. "We're an expected or predictable outcome of our planet's evolution, just as any other intelligent life out there will be." In turn, "maybe other planets are able to achieve these conditions more rapidly than Earth did, while other planets might take even longer," said a release on the paper. There are still unanswered questions. For example, scientists do not know the origin of life on Earth. "This moment of genesis is currently lost in the mists of time, and we cannot yet say whether it was a fluke one-off event or whether it was an easy step," said While the new paper is not proof that intelligent life was intended to happen, it does offer a different perspective on evolution. The theory also opens the door to the consideration of intelligent life after humans on Earth. "If we were to go extinct, some other form of intelligent life could readily emerge in our stead," said Popular Science. "And humanity is less likely to be alone in the universe than we thought."
Asharq Al-Awsat
15-02-2025
- Science
- Asharq Al-Awsat
Was the Emergence of Intelligent Life on Earth Just a Fluke? Some Scientists Think Not
Roughly 300,000 years ago, our species first appeared on the African landscape before spreading globally and coming to dominate the planet. All this happened about 4.5 billion years after Earth formed, with innumerable steps occurring in between that made our planet a cradle for intelligent life. An influential scientific thesis - called the "hard steps" theory and first presented in 1983 - has held that this outcome was a long shot and that the emergence of technological-level intelligent life on Earth or elsewhere was highly improbable. But perhaps this result was not so unlikely after all, according to scientists who are now advancing an alternative theory, Reuters reported. These scientists propose that Homo sapiens and analogous extraterrestrial life forms may be the probable end result of biological and planetary evolution when a planet has a certain set of attributes that make it habitable, rather than requiring countless lucky breaks. The path toward intelligent life, they argue, may be more of a predictable process, unfolding as global conditions allow in a manner that should not be considered unique to Earth. "In short, our framework shows how hard steps may not actually exist - past evolutionary transitions that needed to happen for us humans to be here may not have been hard or unlikely in the available time," said Dan Mills, a postdoctoral researcher in geomicrobiology at the University of Munich and lead author of the study published on Friday in the journal Science Advances, opens new tab. Physicist Brandon Carter devised the hard steps theory. It stresses that the long road to the emergence of humankind necessitated passage through various intermediate steps, each highly unlikely. Over the years, scientists have tried to identify some of these hard steps. These include the emergence of single-celled living organisms on primordial Earth, the initial oxygenation of the atmosphere by photosynthesis, the evolutionary transition from prokaryotic cells that lack a nucleus and other internal structures to eukaryotic cells that have them, and the appearance of complex organisms such as multicellular animals. And then, the final proposed hard step is the appearance of Homo sapiens and milestones such as language and technology. A species with advanced technological capabilities emerged on Earth relatively late in the Earth's habitable history, with the sun expected to increase in luminosity and boil away our planet's oceans about a billion years from now. This has inspired the argument that Earth is an incredibly rare planet that managed to accomplish the needed hard steps before becoming rendered uninhabitable. The new theory was devised by a team of two geobiologists and two astronomers. They propose that humankind's emergence followed the sequential opening of various "windows of habitability" over Earth's history, driven by factors such as changes in nutrient availability, sea surface temperatures, ocean salinity levels and atmospheric oxygen levels. Due to these factors, Earth only relatively recently became hospitable to a species like ours, they said, and that once those conditions existed the evolutionary path was relatively rapid. "Biological innovations proposed as hard or unlikely might actually occur quickly - geologically speaking - as soon as the environment permits," said Penn State microbiologist Jennifer Macalady, one of the researchers. "For example, life might have originated very quickly once temperatures were appropriate for the stability of biomolecules and liquid water. The Earth has only been habitable for humans since the second rise of oxygen in the atmosphere approximately 0.5 billion years ago, meaning that humans could not have evolved on Earth prior to that relatively recent moment," Macalady added. Astronomers are searching for evidence of life beyond Earth and have identified roughly 5,800 exoplanets - planets beyond our solar system. Some of them are uninhabitable gas giants akin to Jupiter but some of them are rocky worlds like our solar system's four terrestrial planets that include Earth. Astrophysicist and study co-author Jason Wright, director of the Penn State Extraterrestrial Intelligence Center, said that a best estimate right now is that somewhere around half of stars have a planet about the size of Earth orbiting at about the right distance to host liquid water, a key ingredient for life. "Understanding the probability of intelligent life emerging helps us understand our own place in the world," Mills said. "Are we humans a cosmic fluke, as the hard steps model predicts? Or are we instead the more expected and typical outcome of a living planet, as our alternative framework suggests?"
Reuters
14-02-2025
- Science
- Reuters
Was the emergence of intelligent life on Earth just a fluke? Some scientists think not
WASHINGTON, Feb 14 (Reuters) - Roughly 300,000 years ago, our species first appeared on the African landscape before spreading globally and coming to dominate the planet. All this happened about 4.5 billion years after Earth formed, with innumerable steps occurring in between that made our planet a cradle for intelligent life. An influential scientific thesis - called the "hard steps" theory and first presented in 1983 - has held that this outcome was a long shot and that the emergence of technological-level intelligent life on Earth or elsewhere was highly improbable. But perhaps this result was not so unlikely after all, according to scientists who are now advancing an alternative theory. These scientists propose that Homo sapiens and analogous extraterrestrial life forms may be the probable end result of biological and planetary evolution when a planet has a certain set of attributes that make it habitable, rather than requiring countless lucky breaks. The path toward intelligent life, they argue, may be more of a predictable process, unfolding as global conditions allow in a manner that should not be considered unique to Earth. "In short, our framework shows how hard steps may not actually exist - past evolutionary transitions that needed to happen for us humans to be here may not have been hard or unlikely in the available time," said Dan Mills, a postdoctoral researcher in geomicrobiology at the University of Munich and lead author of the study published on Friday in the journal Science Advances, opens new tab. Physicist Brandon Carter devised the hard steps theory. It stresses that the long road to the emergence of humankind necessitated passage through various intermediate steps, each highly unlikely. Over the years, scientists have tried to identify some of these hard steps. These include the emergence of single-celled living organisms on primordial Earth, the initial oxygenation of the atmosphere by photosynthesis, the evolutionary transition from prokaryotic cells that lack a nucleus and other internal structures to eukaryotic cells that have them, and the appearance of complex organisms such as multicellular animals. And then, the final proposed hard step is the appearance of Homo sapiens and milestones such as language and technology. A species with advanced technological capabilities emerged on Earth relatively late in the Earth's habitable history, with the sun expected to increase in luminosity and boil away our planet's oceans about a billion years from now. This has inspired the argument that Earth is an incredibly rare planet that managed to accomplish the needed hard steps before becoming rendered uninhabitable. The new theory was devised by a team of two geobiologists and two astronomers. They propose that humankind's emergence followed the sequential opening of various "windows of habitability" over Earth's history, driven by factors such as changes in nutrient availability, sea surface temperatures, ocean salinity levels and atmospheric oxygen levels. Due to these factors, Earth only relatively recently became hospitable to a species like ours, they said, and that once those conditions existed the evolutionary path was relatively rapid. "Biological innovations proposed as hard or unlikely might actually occur quickly - geologically speaking - as soon as the environment permits," said Penn State microbiologist Jennifer Macalady, one of the researchers. "For example, life might have originated very quickly once temperatures were appropriate for the stability of biomolecules and liquid water. The Earth has only been habitable for humans since the second rise of oxygen in the atmosphere approximately 0.5 billion years ago, meaning that humans could not have evolved on Earth prior to that relatively recent moment," Macalady added. Astronomers are searching for evidence of life beyond Earth and have identified roughly 5,800 exoplanets - planets beyond our solar system. Some of them are uninhabitable gas giants akin to Jupiter but some of them are rocky worlds like our solar system's four terrestrial planets that include Earth. Astrophysicist and study co-author Jason Wright, director of the Penn State Extraterrestrial Intelligence Center, said that a best estimate right now is that somewhere around half of stars have a planet about the size of Earth orbiting at about the right distance to host liquid water, a key ingredient for life. "Understanding the probability of intelligent life emerging helps us understand our own place in the world," Mills said. "Are we humans a cosmic fluke, as the hard steps model predicts? Or are we instead the more expected and typical outcome of a living planet, as our alternative framework suggests?" here.
