Latest news with #UniversityofMunich
Korea Herald
08-05-2025
- Entertainment
- Korea Herald
Korean-born German philosopher Han Byung-chul recognized in Spain for advancing humanities, social thought
Korean-born German philosopher and essayist Han Byung-chul has been named the recipient of Spain's 2025 Princess of Asturias Award for Communication and Humanities, the award committee announced Thursday. The Princess of Asturias Awards recognize 'the scientific, technical, cultural, social and humanitarian work carried out at an international level by individuals, institutions or groups of individuals or institutions.' Considered one of the most prominent contemporary philosophers, Han has developed the concepts of the 'burnout society," the 'transparency society' and "shanzhai," a Chinese neologism meaning "fake," through which he traces the mode of deconstruction in Chinese culture, according to the jury for the award, convened by the Princess of Asturias Foundation. Born in 1959, Han studied German literature and theology at the University of Munich, and philosophy at the University of Freiburg, where he received a Ph.D. in 1994 for his dissertation on Martin Heidegger. He has taught at the University of Basel (Switzerland, 2000-2012) and has lectured in philosophy and cultural studies at the University of Fine Arts in Berlin, after having worked at the Karlsruhe University of Arts and Design, alongside philosophy and media art professor Peter Sloterdijk. This year's Communication and Humanities Award saw 47 nominations from 16 countries. It is the first of the eight Princess of Asturias Awards to be announced in the prize's 45th edition. The corresponding awards in the categories of literature, social sciences the arts, sports, concord, technical and scientific research and international cooperation will be announced in the coming weeks. The awards ceremony will be held in October in Oviedo, Spain, and will be presided over by King Felipe VI and Queen Letizia, alongside Princess Leonor and Infanta Sofia. Each laureate receives a Joan Miro sculpture, a diploma, an insignia and a cash prize of 50,000 euros ($56,500).
Yahoo
30-04-2025
- Politics
- Yahoo
How a reading group helped young German students defy the Nazis and find their faith
For three weeks in April 2025, my 'Theology of Christian Martyrdom' class studied how a group of German students and professors from Munich and Hamburg formed a resistance movement from 1942 to 1943 known as the 'White Rose.' These individuals defied Nazi tyranny, they were imprisoned, and many were executed. At the movement's center were Hans Scholl, Sophie Scholl, Alexander Schmorell, Christoph Probst and Willi Graf, who were all in their 20s, and Professor Kurt Huber. The Scholl siblings, their friends and their professor were beheaded for urging students at the University of Munich to oppose the Nazi regime. On the surface, the White Rose's 'crime' was the writings, printings and distribution of six anti-Nazi pamphlets urging Germans to resist Adolf Hitler and work to end World War II. However, a closer examination of their pamphlets, along with excerpts from their diaries and letters, reveals that their resistance was rooted in something deeper – a faith anchored in friendship and a humanistic learning. Their time together reading and discussing theological texts deepened their Christian faith. Teaching this class taught me that teachers can inspire students to improve their country's social and political landscape through the study of literature, history and theology. Teachers can help students form their consciences and empower them to act against falsehood and injustice. These young people came from a variety of Christian backgrounds, including Catholic, Lutheran and Orthodox traditions. Some had been members of the Hitler Youth as teenagers, while others had served as medical assistants in the German army. They formed strong bonds and underwent personal transformations as students at the University of Munich, where they were mentored by a couple of philosophers, especially Kurt Huber, who was a devout Catholic. The students met regularly and secretly with their professors to study literature, philosophy and theology from the Catholic intellectual tradition, banned by the Nazi regime as part of Hitler's strategy to first stifle and then strangle the Catholic Church in Germany. Based on the students' correspondence and diaries, their covert engagement with Catholic thought became a cornerstone of the White Rose's rejection of Nazi tyranny. In the works of the fifth-century North African theologian Augustine, the 20th-century novelist and playwright Georges Bernanos, and the 20th-century philosopher Jacques Maritain, these students encountered a Catholic intellectual tradition that was responsive to the urgent questions of their time. From Augustine they learned the importance of cultivating an interior life grounded in prayer. Bernanos stressed the importance of embracing one's humanity to confront evil. Maritain emphasized the need to strive for a free democratic society. The White Rose movement was concerned not only with the present state of humanity but also with its future, and not only with the individual but also with the communal. In their clandestine meetings and correspondence, they wrestled with the relationship between faith and reason, goodness in the face of evil, the meaning of tyranny, the nature of a just state, and the foundations of genuine liberty. Addressing these serious issues not only matured their intellects but also deepened their hearts; it taught them the importance of prayer. 'Better to suffer intolerable pain than to vegetate insensibly. Better to be parched with thirst, better to pray for pain, pain, and more pain, than to feel empty, and to feel so without truly feeling at all. That I mean to resist,' Sophie wrote in her diary in the early summer of 1942. The personal writings of the White Rose reflect a religious passion, akin to the prayers of saints. For example, in his imprisonment, Graf stated: 'I know my Redeemer liveth. This faith alone strengthens and sustains me.' The impact of Christianity on the inner lives of these young people is a crucial part of their narrative and resistance. Their circle of friendship became a haven in a totalitarian state that sought to isolate individuals, instill fear and transform these estranged and fearful people into part of a mass society. 'We negated the many, and built on the few, and believed ourselves strong,' Traute Lafrenz, the last surviving member of the White Rose and a member of the Hamburg circle, later stated. The most significant intellectual influence on the group may have been John Henry Newman, a 19th-century Catholic convert and theologian who emphasized the primacy of a 'well-formed' conscience. His writings helped them recognize what Catholics like myself see as a moral truth that transcended Nazi propaganda – that each person bears within them the voice of the living God. This voice could not be silenced by state power. Newman insisted that conscience is not merely intuitive but is shaped through learning – from conversations, books and lived experience. With their professors' guidance, the White Rose students were able to cultivate their conscience. If Newman were addressing college students today, I like to believe he would emphasize the significance of their conversations with friends on campus, the discussions held with classmates and professors in the classroom, the newspapers they read, the retreats they participated in, the novels they savored during the holidays, their road trips across the country, and their studies abroad. All of these experiences contribute to shaping their conscience. Newman's defense of broad, active and serious learning offered an appealing counterpoint to Nazi ideology, which sought not only to deprive individuals of their civil rights but also to crush their inner lives and capacity to form meaningful relationships through terror and fear. The power of a well-formed conscience is perhaps best illustrated by Sophie Scholl, who shared Newman's sermons with her boyfriend, Fritz Hartnagel, a Wehrmacht officer who fought for Germany during World War II. In the summer of 1942, horrified by the brutality he witnessed, Hartnagel wrote to Scholl that Newman's words were like 'drops of precious wine.' In another letter, he wrote: 'But we know by whom we are created, and that we stand in a relationship of moral obligation to our Creator. Conscience gives us the capacity to distinguish between good and evil.' After the war, Hartnagel became active in the peace movement and supported conscientious objectors. To the members of the White Rose, conscience was a spiritual stronghold – one the state could not breach. I believe that while my students today face different challenges – a society shaped by what I regard as the nihilistic presence of technological power and populism, rather than full-blown totalitarianism – they also aspire to act with clarity and conviction. Newman's view on the formation of conscience resonated with my students as well. What my students share with those young dissidents from over 80 years ago is a commitment to cultivating an inner life, fostering a community of friends and engaging in a vibrant intellectual tradition. They are drawn to the writings that animated Hans Scholl, who, drawing inspiration from the Catholic playwright Paul Claudel, wrote the following just two days before his arrest. 'Chasms yawn and darkest night envelops my questing heart, but I press on regardless. As Claudel so splendidly puts it: Life is one great adventure into the light.' As a teacher, I believe that young people want to engage with an intellectual tradition that helps them discover their vocation and live with integrity, similar to Scholl. They seek to act with a clear conscience amid the uncertainties of their own times. This approach serves as a powerful contrast to any hollow, anti-intellectual and culturally bankrupt tyranny. This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Peter Nguyen, SJ, College of the Holy Cross Read more: Spider-Man's lessons for us all on the responsibility to use our power, great or small, to do good Genocide resisters, long overlooked by history, step into the spotlight How individual, ordinary Jews fought Nazi persecution − a new view of history Peter Nguyen, SJ does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Yahoo
22-02-2025
- Science
- Yahoo
Boost for alien hunters? Earth life may not be so improbable, study suggests
When you buy through links on our articles, Future and its syndication partners may earn a commission. The concept of the "great filter" to explain why so far we seem to be alone in the universe is based on erroneous assumptions, according to a new model that describes how life on Earth evolved in step with changing geobiological conditions rather than through a series of improbable events. "We're arguing that intelligent life may not require a series of lucky breaks to exist," said lead author Dan Mills of the University of Munich in a statement. "Humans didn't evolve 'early' or 'late' in Earth's history, but 'on time' when the conditions were in place." It was the Australian physicist Brandon Carter who first popularized the notion that life on Earth was the result of a sequence of unlikely events, which he described as "hard steps" in a 1983 paper. A black hole theorist, from time to time Carter also dipped his hand into more existential matters, specializing in drawing assumptions from probabilistic and anthropic (i.e. the argument that conclusions about the nature of the cosmos have to be constrained by the fact that we exist) reasoning to say something about our existence in the universe. Related: The search for alien life This is no better seen than in his Doomsday argument, in which Carter posits that we, as individuals, are more likely to exist at a time when the greatest number of humans are alive. For example, imagine every human who ever lived is given a number based on the order in which they were born, and then these numbers are pulled from a pot like the numbers in a lottery — you're more likely to pull a higher number than a very low number if the total number of humans who have lived and will ever live is large. Since population growth can be modeled as exponential, the fact that we exist now with a relatively low birth number compared to all the hundreds of billions to trillions of people who will follow us suggests that something catastrophic could be about to happen to the human race that will curtail future population numbers. At least, that's the argument; philosophers and statisticians have been arguing about it ever since Carter proposed it. Carter's "hard steps" model of our evolution on Earth is similarly probabilistic in nature. The sun is nearing the halfway point of its approximately 10-billion-year lifespan, and yet it's taken us — Homo sapiens — nearly all of that time to arrive on the scene. Carter could not see any reason why it would take so long for human-like life to evolve on Earth if complex life is common in the universe. This suggested to Carter that the development of human-like life must be difficult, passing through a series of evolutionary bottlenecks for which the chances of life succeeding are so remote that we would not typically expect those evolutionary transitions to occur in the lifetime of Earth. Life on our planet would therefore be a complete fluke, unlikely to be repeated elsewhere in the universe. The hard steps idea has subsequently morphed into the concept of the "great filter," the idea that something in the history of all life inevitably brings that life to an end. Suggested great filters have included the origin of life in the first place, the evolution of technological life and the ability of said life to wipe itself out. The existence of the great filter would certainly help explain the apparent "great silence" in the universe that SETI (search for extraterrestrial intelligence) researchers have encountered, with no confirmed evidence of alien life in all the decades that we have been searching. However, like the Doomsday argument, the "hard steps" model has its critics, and now adding to them are the authors of a new paper that highlights what they say is 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. However, the new paper by Mills (a geomicrobiologist), along with Penn State University co-authors Jennifer Macalady (a professor of geosciences), Adam Frank and Jason Wright (both astrophysicists), points out that the age of the sun and therefore the Earth very much have something to do with it. The team selected five of the more universally agreed-upon "hard steps:" the origin of life, the evolution of eukaryotes (organisms with cells made from a nucleus containing genetic information surrounded by a membrane), the oxygenation of Earth's atmosphere, the development of complex multicellular life and the arrival of Homo sapiens. They then looked at how geological and atmospheric changes to Earth might have affected when these supposedly hard steps occurred. If Earth were initially hostile to these supposed hard steps, it would naturally explain why they took so long to pass — because they had to wait for Earth to reach the point where they could be possible. Take, for example, the oxygenation of Earth's atmosphere. For over two billion years after its formation, Earth's atmosphere was mostly carbon dioxide. It was only about 2.1 to 2.4 billion years ago that Earth's atmosphere began to fill with oxygen. This was thanks to the onset of photosynthesis, brought about by the evolution of microbes called cyanobacteria. In turn, the development of cyanobacteria relied on certain climactic and environmental conditions. In some models, the oceans of this era were hot, and the water would have had to cool below 70 degrees Celsius (158 degrees Fahrenheit) for cyanobacteria to evolve. In other models, conditions were milder and the development of cyanobacteria then depended upon the availability of freshwater and how much of Earth's landmass was above sea level. Either way, cyanobacteria's evolution and the onset of photosynthesis and the oxygenation of the atmosphere was delayed until these conditions were met; it couldn't have happened any sooner. And even once cyanobacteria were ingesting carbon dioxide and exhaling oxygen via photosynthesis, it took time for oxygen levels to build up. Multicellular life requires a certain abundance of oxygen, with more complex life in general requiring more oxygen. The oxygen abundance in the atmosphere suitable for the evolution of Homo sapiens didn't occur until 400 million years ago — meaning that for 91% of Earth's history, there wasn't enough oxygen in the atmosphere to support human life. In other words, Mills' team propose that these were not "hard steps" as Carter saw them, but that life simply had to wait until Earth could facilitate them — that Earth and life had to co-evolve together. Related: Fermi Paradox: Where are the aliens? Related stories: — SETI & the search for extraterrestrial life — Does alien life need a planet to survive? Scientists propose intriguing possibility — Alien life may not be carbon-based, study suggests Other variables that may have had an effect on how soon the different stages of life's evolution could occur include atmospheric ozone levels, nutrient availability, decreasing sea surface temperatures, decreasing ocean salinity, snowball Earth periods in which the planet completely iced over, and the development of plate tectonics. "This is a significant shift in how we think about the history of life," said Macalady. "It suggests that the evolution of complex life may be less about luck and more about the interplay between life and its environment, opening up exciting new avenues of research in our quest to understand our origins and our place in the universe." We know from geological evidence that life existed on Earth as early as 3.7 billion years ago, and possibly even earlier. The initial development of life on Earth is known as the "habitability boundary." As different windows of habitability subsequently opened up, life would have been able to evolve in bursts. And if this is the way it happens on Earth, it could be the way it happens on other worlds, too — and perhaps faster or more slowly, depending upon how the geology of those worlds develops. There is a caveat, in that evolutionary biologists still do not understand how life originated 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. One possibility is that life developed on multiple occasions on Earth, but all the other lineages went extinct, leaving only ourselves — the descendants of LUCA, the last universal common ancestor, from which all known life on Earth evolved — as the only ones left standing. This would give the illusion that life originated only once when it could have had several independent origins. Other mysteries include how biological cells first evolved, and what caused the dramatic onset of complex life during the Cambrian explosion 540 million years ago. It is still entirely possible that these were unique and rare events, but the new paper is not arguing that life is common in the universe, only that the concept of hard steps in evolution is not necessarily true and that the development of planetary environments has a big role to play, counter to Carter's original model. Another caveat is that, so far, astronomers have not yet found another world like Earth, so geologists cannot yet say whether the way in which Earth's geology and atmosphere developed is typical or not. It could yet be that creating a habitable world is where the hard steps really lie. Until we discover true extraterrestrial life, whether that be microbes on Mars or bonafide little green men, we will continue to grapple with the possibility that Earth and its life are unique. For now, it's a lonely universe out there. The Mills et al paper was published on Feb. 14 in the journal Science Advances.
Yahoo
22-02-2025
- Science
- Yahoo
Boost for alien hunters? Earth life may not be so improbable, study suggests
When you buy through links on our articles, Future and its syndication partners may earn a commission. The concept of the "great filter" to explain why so far we seem to be alone in the universe is based on erroneous assumptions, according to a new model that describes how life on Earth evolved in step with changing geobiological conditions rather than through a series of improbable events. "We're arguing that intelligent life may not require a series of lucky breaks to exist," said lead author Dan Mills of the University of Munich in a statement. "Humans didn't evolve 'early' or 'late' in Earth's history, but 'on time' when the conditions were in place." It was the Australian physicist Brandon Carter who first popularized the notion that life on Earth was the result of a sequence of unlikely events, which he described as "hard steps" in a 1983 paper. A black hole theorist, from time to time Carter also dipped his hand into more existential matters, specializing in drawing assumptions from probabilistic and anthropic (i.e. the argument that conclusions about the nature of the cosmos have to be constrained by the fact that we exist) reasoning to say something about our existence in the universe. Related: The search for alien life This is no better seen than in his Doomsday argument, in which Carter posits that we, as individuals, are more likely to exist at a time when the greatest number of humans are alive. For example, imagine every human who ever lived is given a number based on the order in which they were born, and then these numbers are pulled from a pot like the numbers in a lottery — you're more likely to pull a higher number than a very low number if the total number of humans who have lived and will ever live is large. Since population growth can be modeled as exponential, the fact that we exist now with a relatively low birth number compared to all the hundreds of billions to trillions of people who will follow us suggests that something catastrophic could be about to happen to the human race that will curtail future population numbers. At least, that's the argument; philosophers and statisticians have been arguing about it ever since Carter proposed it. Carter's "hard steps" model of our evolution on Earth is similarly probabilistic in nature. The sun is nearing the halfway point of its approximately 10-billion-year lifespan, and yet it's taken us — Homo sapiens — nearly all of that time to arrive on the scene. Carter could not see any reason why it would take so long for human-like life to evolve on Earth if complex life is common in the universe. This suggested to Carter that the development of human-like life must be difficult, passing through a series of evolutionary bottlenecks for which the chances of life succeeding are so remote that we would not typically expect those evolutionary transitions to occur in the lifetime of Earth. Life on our planet would therefore be a complete fluke, unlikely to be repeated elsewhere in the universe. The hard steps idea has subsequently morphed into the concept of the "great filter," the idea that something in the history of all life inevitably brings that life to an end. Suggested great filters have included the origin of life in the first place, the evolution of technological life and the ability of said life to wipe itself out. The existence of the great filter would certainly help explain the apparent "great silence" in the universe that SETI (search for extraterrestrial intelligence) researchers have encountered, with no confirmed evidence of alien life in all the decades that we have been searching. However, like the Doomsday argument, the "hard steps" model has its critics, and now adding to them are the authors of a new paper that highlights what they say is 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. However, the new paper by Mills (a geomicrobiologist), along with Penn State University co-authors Jennifer Macalady (a professor of geosciences), Adam Frank and Jason Wright (both astrophysicists), points out that the age of the sun and therefore the Earth very much have something to do with it. The team selected five of the more universally agreed-upon "hard steps:" the origin of life, the evolution of eukaryotes (organisms with cells made from a nucleus containing genetic information surrounded by a membrane), the oxygenation of Earth's atmosphere, the development of complex multicellular life and the arrival of Homo sapiens. They then looked at how geological and atmospheric changes to Earth might have affected when these supposedly hard steps occurred. If Earth were initially hostile to these supposed hard steps, it would naturally explain why they took so long to pass — because they had to wait for Earth to reach the point where they could be possible. Take, for example, the oxygenation of Earth's atmosphere. For over two billion years after its formation, Earth's atmosphere was mostly carbon dioxide. It was only about 2.1 to 2.4 billion years ago that Earth's atmosphere began to fill with oxygen. This was thanks to the onset of photosynthesis, brought about by the evolution of microbes called cyanobacteria. In turn, the development of cyanobacteria relied on certain climactic and environmental conditions. In some models, the oceans of this era were hot, and the water would have had to cool below 70 degrees Celsius (158 degrees Fahrenheit) for cyanobacteria to evolve. In other models, conditions were milder and the development of cyanobacteria then depended upon the availability of freshwater and how much of Earth's landmass was above sea level. Either way, cyanobacteria's evolution and the onset of photosynthesis and the oxygenation of the atmosphere was delayed until these conditions were met; it couldn't have happened any sooner. And even once cyanobacteria were ingesting carbon dioxide and exhaling oxygen via photosynthesis, it took time for oxygen levels to build up. Multicellular life requires a certain abundance of oxygen, with more complex life in general requiring more oxygen. The oxygen abundance in the atmosphere suitable for the evolution of Homo sapiens didn't occur until 400 million years ago — meaning that for 91% of Earth's history, there wasn't enough oxygen in the atmosphere to support human life. In other words, Mills' team propose that these were not "hard steps" as Carter saw them, but that life simply had to wait until Earth could facilitate them — that Earth and life had to co-evolve together. Related: Fermi Paradox: Where are the aliens? Related stories: — SETI & the search for extraterrestrial life — Does alien life need a planet to survive? Scientists propose intriguing possibility — Alien life may not be carbon-based, study suggests Other variables that may have had an effect on how soon the different stages of life's evolution could occur include atmospheric ozone levels, nutrient availability, decreasing sea surface temperatures, decreasing ocean salinity, snowball Earth periods in which the planet completely iced over, and the development of plate tectonics. "This is a significant shift in how we think about the history of life," said Macalady. "It suggests that the evolution of complex life may be less about luck and more about the interplay between life and its environment, opening up exciting new avenues of research in our quest to understand our origins and our place in the universe." We know from geological evidence that life existed on Earth as early as 3.7 billion years ago, and possibly even earlier. The initial development of life on Earth is known as the "habitability boundary." As different windows of habitability subsequently opened up, life would have been able to evolve in bursts. And if this is the way it happens on Earth, it could be the way it happens on other worlds, too — and perhaps faster or more slowly, depending upon how the geology of those worlds develops. There is a caveat, in that evolutionary biologists still do not understand how life originated 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. One possibility is that life developed on multiple occasions on Earth, but all the other lineages went extinct, leaving only ourselves — the descendants of LUCA, the last universal common ancestor, from which all known life on Earth evolved — as the only ones left standing. This would give the illusion that life originated only once when it could have had several independent origins. Other mysteries include how biological cells first evolved, and what caused the dramatic onset of complex life during the Cambrian explosion 540 million years ago. It is still entirely possible that these were unique and rare events, but the new paper is not arguing that life is common in the universe, only that the concept of hard steps in evolution is not necessarily true and that the development of planetary environments has a big role to play, counter to Carter's original model. Another caveat is that, so far, astronomers have not yet found another world like Earth, so geologists cannot yet say whether the way in which Earth's geology and atmosphere developed is typical or not. It could yet be that creating a habitable world is where the hard steps really lie. Until we discover true extraterrestrial life, whether that be microbes on Mars or bonafide little green men, we will continue to grapple with the possibility that Earth and its life are unique. For now, it's a lonely universe out there. The Mills et al paper was published on Feb. 14 in the journal Science Advances.
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?"
