Evolution Before “Life”
Our story about life in the cosmos starts at the equator where Dian Fiantis, a professor of soil science at Andalas University in Indonesia, investigated how the seemingly dead environment came back to life. In 2018, she traveled to Mt. Anak Krakatoa (which emerged after the famous Krakatoa eruption) to collect the volcanic ash it ejected two months before. In her lab, she found out that volcanic glass (SiO2), the dominant chemical found in the ash, has super tiny holes that could store water. “A good place for cyanobacteria to grow,” said Francis. The microbe, which scientists called “nature’s little alchemist”, engineered the surrounding environment so that complex living systems like lichens and vascular plants grow.
Fiantis’ research shows us what happened “before life” in our modern time. It might not tell us how life began in the early earth. But this is the closest example of the blurred line between life and non-life. Just like a meteor impact or active hydrothermal vents, a volcanic eruption could represent the hellish condition where we could “mix things up and select for chemical configurations and try new things [that lead to life],” said Robert Hazen, a mineralogist from Carnegie Institute of Sciences.
Hazen is one of many scientists who are now the proponent of “evolution before life”, an idea referring to a universal chemical evolution that spans billions of years and comprises all possible space in the universe. It argues that life emerged gradually from simplicity to complexity, undergoing selections until it reached biological functions. “I think it’s a really exciting [research] avenue,” says Leroy Cronin at the University of Glasgow.
Science can’t create life from scratch yet and no one can explain how exactly life emerged on Earth in the first place. But the theory of chemical evolution, which stands on hundreds of scientific papers since the 1990s, is a promising start to finally rationalize science’s greatest enigma. It is not an “earth-bound” theory, testable with current AI technology. “I am very much a believer that it is the future of origins of life research,” says Joshua Goldford, a computational biologist at California Institute of Technology.
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One day in May, greyish clouds were hovering in the sky of Providence, Rhode Island. On the ground, as we had walked ten minutes away from the city’s train station, we arrived at a convention center. Here, hundreds of scientists gathered for the Astrobiology Conference (AbSciCon) 2024, organized by the American Geological Union (AGU). On the first floor, the exhibition hall was full of posters explaining the possibility of life elsewhere, but people were flocking upstairs for afternoon parallel sessions. One of these, a session called “Evolution Before Life”, attracted many participants. Some of them standing at the back because the room was full.
Hazen opened the session with his talk on mineral evolution. He says that, from the earth’s formation 4.6 billion years ago, there is a pattern of increasing complexity in mineral history, resulting in more than 6000 complex minerals we know today. He thinks the existing laws of nature are not enough to explain such a pattern in the universe. There must be another law that governs how atoms and molecules come together to create more and more complex entities across time, he says.
For years, Hazen worked with a team of scientists and philosophers to develop “the law of evolving systems” which is a process of chemical evolution based on the selection of “functions”. In the mineral evolution case, the selected function is its stability. The more stable the mineral, the more likely it survive. This process of selection applies to all matters that compose living and non-living things in the universe, including the continuum chain of processes that connect the two worlds or what is popularly known as “the origins of life”.
But biologists aren’t sure about the term “evolution” used by chemists and mineralogists. In the Q and A session, some biologists highlighted how they thought differently. One argued that linear progress from simplicity to complexity is not the heart of biological evolution. Each microbial world, for example, is unique and it doesn’t make them more “advanced” than the other group. Instead of a “ladder”, biological evolution is a tree with messy branches.
Greg Fournier, a geobiologist from Massachusetts Institute of Technology (MIT), says that both chemical and biological evolution “can include selection and generated diversity,” but he says only biological evolution has a concrete form of heritable information in the process, a concept that chemists are trying to make sense nowadays.
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After the lunch break, when we were about to go downstair, we saw Hazen going up on the other side of the escalator. We decided to stop, said hello, and asked him for a brief chat. The scientist, who has published more than 25 books on mineralogy and the origins of life science, welcomed our invitation. We talked in a corner of the hall, near the windowpane. When asked about biologists’ criticism of his idea in his session, he said “I didn’t quite understand what they meant,”. For him, evolution is not exclusive to the living world. The process of selection, as a driver for increasing complexity, applies to many other worlds such as music, and languages, as well as what we have been talking about so far: chemistry.
The idea of “evolution before life” is not a new thing in science, says Hazen. In the 1990s, in his book “At Home in the Universe”, Stuart Kauffman proposed an idea of how self-organization of matters could lead to “spontaneous order”. (In fact, Kauffman helped review Hazen’s recent paper on mineral evolution). Hazen also worked with Jack Sozstack, a veteran prebiotic chemist at the University of Chicago, to build the term “functional information” when they wanted to explain how molecular complexity relates to its function. Hundreds of research papers also worked on the term “emergence” and “chemical evolution”. The science is quite strong. It stands on the shoulders of giants.
Hazen wonders if the hesitation surrounding the idea, especially his law of evolving system, is more about its philosophical implication. Imagine a white paper cup in your hand. Hazen says science could describe its materials, shape, mass, and other quantitative measures but it never explains function. It could be a place for coffee, tea, and pencils. The function is contextual. “And when you’re saying function, you’re saying purpose,” he said. This is what many scientists are not comfortable with.
Scientists might believe in “prejudice” that science is valueless with no purpose, he says. But “that’s not the way we experience the universe,”. For Hazen, there are two arrows of time. The first arrow follows the second law of thermodynamics where things are heading to destructions and disorders. We see red maple leaves falling in fall, white hair appearing in our reflection in the mirror, or even the death of loved ones. But, says Hazen, we also see children born, flower buds popping out from dried branches, or lush rainforests growing out of volcanic ash. It is the second arrow of time: an arrow of increasing order in the universe. “For me science should explain this experience,”
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Hazen is not the only one who thinks that evolution happened before life. Cronin developed Assembly Theory, a theory that echoes a similar idea on how life evolved through the process of chemical selection. But for Cronin, for a theory to be validated, it needs to be confirmed by experiments. Also, “It must be able to predict something new,”. In his lab, his team quantifies molecule complexities, seeing the process of chemical selections with an AI-supported approach they called “digital chemistry”. Silke Asche, Cronin’s PhD student, presented one of these experiments in AbSciCon too, together with other young female researchers like Kavita Matange from Georgia Tech University and Selenna Canelli from Tokyo Institute of Technology.
Indeed, professors like Hazen and Cronin are just the tip of the iceberg. On the surface, an increasing number of young scientists share the enthusiasm. The idea of AbSciCon’s ‘Evolution Before Life” came from Tymofii Sokolskyi, a PhD student at the University of Wisconsin Madison. “To understand the origins of life, we must understand what are the simplest systems that can evolve,” he says. Sokolskyi says “a lot of awesome research” is happening on the idea of “evolution before life”, leading him to propose a session with Vahab Rajaei at Georgia Institute of Technology and Michael Wong from Carnegie Institute of Science.
Wong, a fan of Star Trek and an enthusiastic science communicator, is Hazen’s co-author in The Law of Evolving System. We met him one morning in a café near Porter Square, Cambridge. Over coffee and croissants, we talked about a wide range of subjects. From his childhood decision to worship Poseidon and other Greek gods, he found a local library book (a funny experience which showed him human’s natural affinity to something greater) to the serious debate of the definition of “life”. The latter is his particular concern. One that inspired him to work with Hazen.
“The search for life was very confined to life as we know it,” he says. As he discussed with Carol Cleland, a philosopher of science at the University of Colorado, he realized that he needed to have a “Goldilocks level of abstraction,”. The thinking goes like this: if we are too narrow in defining life, we might miss life that is slightly different than us. But if we are too abstract, we might find false-positive results like fire or hurricane, for example. “I wanted to help develop that kind of abstraction,” he says. For him, data and information are amazing tools to do so.
Goldford, the computational biologist from Caltech, also has a case for evolution before life. He thinks evolution works on a bigger time scale, far before biology. The clue lies in the energy processing inside every living cell, a process known as metabolism. Microbes, the simplest and oldest living thing, have diverse kinds of metabolic pathways but if we look at it closely, says Goldford, we find many “commonalities and shared mechanisms”. This led him to the idea of “the universality of the chemistry of life”.
How did this universality emerge? Given the intense genetic materials-sharing among the microbes in the early earth, Goldford thinks the mechanism can’t be explained by the common Darwinian evolution approach. “It’s the emergence of entirely new functions and chemical reactions in this case,” he says. To test this, he did a computer simulation of how non-living chemicals (like metal ions and inorganic materials) that were found in prebiotic earth might interact. Interestingly, under a set of codes, the algorithm led him to basic metabolic pathways such as the ever-important photosynthesis.
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Chemistry unifies the living and non-living.
From the lens of chemistry too, we see no boundaries. An individual can never be separated from their surroundings as there will always be interaction between their atoms and molecules. This universal law could take us traveling back through time, rationalizing the origins of life. It also allows us to explore the vast cosmos, possibly finding life elsewhere.
Scientists are testing how the idea of “evolution before life” might be able to detect biosignatures in Titan, Enceladus, or even beyond our solar system. But we don’t have to travel very far to appreciate its grandeur meaning. For we live in the only valid sample of life in the universe.
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Six years after Fiantis collected her volcanic ash, life is thriving in the Krakatoa volcanic complex. The nature’s “little alchemist” had enchanted the hellish environment into a tropical paradise through chemical spells. Fiantis found the soils had higher concentrations of certain metals like calcium, magnesium, and phosphorous. All play crucial roles in plant metabolism, acting as an important activator of many biochemical reactions.
Under this spell, green lichens blanketed Anak Krakatoa, 40 species of orchids, six species of mammals, 47 species of birds, 19 species of bats, and 17 species of reptiles roam in its surrounding islands. Creating a scene of life as we know it today and hinting at a chemical evolution that first animated the island.