The movies are short, barely a minute long. To the untrained eye, they show little circular blobs moving slowly from one edge of the frame to the other. The blobs are actually tiny bundles of protein, a few microns across, and the films show how they move spontaneously along chemical gradients – from low pH to high pH, for example. They’re hardly Citizen Kane – but to Alan Moses, who saw the films at a scientific conference in Switzerland in 2024, they were an eye-opener. What if blobs of RNA, known as condensates, behaved like these blobs of protein, seemingly doing things of their own accord? If so, maybe – possibly – the intriguing chemistry documented in these short movies could illuminate one of the oldest and most vexing questions in all of science: How did life begin?   

 “I went around the conference telling everyone I could that the origin of life was an RNA condensate!” recalls Moses, a professor in U of T’s department of cell and systems biology.  

 Back in Toronto, Moses and a graduate student, Jacob Fine, got to work. As theoreticians, they rushed not to the lab but to their computers, keen to model the behaviour of potential RNA condensates. Their paper, “An RNA Condensate Model for the Origin of Life,” was published last year in the Journal of Molecular Biology. In it, they argued that RNA condensates can act as catalysts for chemical reactions. Others in the field have taken note. “We’ve had a fantastic response from biochemists who are starting to do these kinds of experiments,” Moses says.   

 He points out, with appropriate caution, that blobs of RNA are not about to crawl out of their petri dishes and evolve into little worms, or anything else – but, with their ability to form rudimentary structures, and to move almost as if they’re swimming, they’re remarkable nonetheless.  

  “To be clear, these things are not alive,” says Moses, “but they are showing spontaneous organization.”  

Let’s back up for a moment. In 1859, Charles Darwin published his groundbreaking book, On the Origin of Species, explaining how a diverse array of plants and animals likely evolved from simpler forms through a process he called natural selection. While his theory said nothing about how life arose in the first place, Darwin was happy to speculate: In a letter to botanist Joseph Dalton Hooker, penned in 1871, he imagined what sorts of conditions may have prevailed in the early days of our planet and wondered if “some warm little pond” with just the right chemistry may have witnessed the first chapter of life’s grand story.   

Today, Darwin’s warm little pond is just one of several competing ideas. Much attention is also focused on hydrothermal vents – fissures on the ocean floor rich in minerals and superheated water. Might some early organisms have learned how to extract energy from the chemical reactions that unfold in these nearly alien environments? Meanwhile, the molecular building blocks of life, including “nucleobases” – the nitrogen-rich molecules from which both DNA and RNA are made – have been found in meteorites and even in asteroids, suggesting that even if life “took off” here on Earth, its basic components may be relatively common in our solar system and beyond.   

 However – and wherever – it happened, chemical activity somehow gave way to biology: metabolism, the formation of stable structures such as cells, and, ultimately, self-replication. All of this leaves the question of life’s origins as hotly debated today as ever. As Moses points out: “We can’t go back and find out. Nobody was there when life began, so that’s a major, major challenge.”   

Once life did take root, the evolutionary process of natural selection, as Darwin described, could take over. Of course, Darwin knew nothing of the actual mechanism of inheritance. Modern genetics began when the work of botanist Gregor Mendel, carried out in the 1850s and 1860s, was rediscovered in the early 20th century. By mid-century, scientists had deduced the unique structure of DNA and showed how it passes genetic information from one generation to the next.   

 Eventually, though, scientists began to wonder if another molecule, RNA (ribonucleic acid), might play a crucial role. Simpler than DNA, molecules of RNA are noteworthy because they can both transmit genetic information and kick-start chemical reactions. According to the “RNA world” hypothesis, self-replicating RNA molecules could have appeared before DNA and proteins.  

“It’s quite unlikely that all three of those complex biomolecules arose at the same time, or they all just popped into existence,” he says. “So, a logical question is, which of them came first?” According to the RNA world hypothesis, RNA was first out of the gate.  

 The catch is that while RNA can spark chemical reactions, no one has yet shown that RNA can make copies of itself – a step that Moses sees as a key “missing link” in this hypothesis. That’s why he’s excited about these blob-like RNA condensates. “Not only do they form blobs spontaneously, but they also start to do things,” he says. “They can start to form currents of material inside them; they can start to move around… If somebody could show that the RNA condensate can catalyze the formation of RNA, you’ve basically got it, you’ve got all the pieces,” he says. After that, “natural selection does the rest.”  

 Moses concedes, however, that proof of the RNA condensate idea could be elusive. The most convincing evidence, he says, would be to show that such condensates can create new RNA polymers from simpler building blocks – though even this wouldn’t prove that this was what happened four billion years ago. “But it would demonstrate that self-replication – one of the most elusive properties of life – can happen without any special circumstances or complicated replication enzymes,” he says. “It could even lead to ‘origin of life’ experiments, where artificial, living blobs are created and evolved routinely in lab experiments.”  

 Ultimately, however, it would only make the condensate idea more plausible than its competitors. It’s a bit like how cosmologists argue about the origin of the universe, he says: The big bang has become the leading theory, and more and more evidence has been gathered in its favour, “but it’s very hard to imagine a definitive ‘proof’.”  

 Moses is not the only RNA aficionado at U of T. Artem Babaian, a professor in the department of molecular genetics, is fully on board. “The way I view it is, our planet is an RNA planet,” he says. Babaian points out that, for all we know, some type of RNA not only sparked life on Earth billions of years ago but could still be lurking about today – if only we knew how to detect it. “How do you recognize this thing as a living, evolving RNA entity,” he asks, “if you have nothing to compare it to?” He believes that “chemically interesting and diverse RNA molecules” are all around us, and that “we’re at the very cusp of starting to understand that world.” 

Even the life we’re familiar with – the traditional stuff built from DNA – is proving to be far more diverse than we once imagined. In particular, we now know that life flourishes in environments such as hydrothermal vents that were once considered absurdly inhospitable. (An example is the “Pompeii worm.” The creature, which takes its name from the Roman city destroyed by a volcano, can inhabit waters as hot as 80 degrees Celsius.) “We now understand much more about just how many unusual environments life can take advantage of,” says Barbara Sherwood Lollar, a professor in the department of Earth sciences. And hydrothermal vents may be just the beginning. We’re so used to thinking of the plants and animals that thrive on Earth’s surface – and in the ocean and in the sky – that we often forget about the rocks beneath our feet, she says. Could life have gotten its start in one of these overlooked environments? (Sherwood Lollar recalls a colleague who liked to ask, instead of Darwin’s warm little pond, “Why not a warm little fracture?”)   

 While hydrothermal vents and subterranean rock fractures are alien to city-dwelling primates like us, the Earth on which life first took hold, some four billion years ago, looked radically different from today. For starters, there was very little oxygen in the atmosphere; instead, there was a soupy mix of methane, carbon dioxide, water vapour, and hydrogen sulfide, giving the sky an orange hue, while dissolved iron likely gave the oceans a greenish tinge. Volcanoes would have dotted the landscape, and the moon would have loomed closer than today.   

 But the discovery of extremophiles has taught us that life can flourish even in the harshest of conditions – and studying them is changing not only how we think about life on our own planet, but also where it might exist elsewhere in the solar system and beyond.   

 Astrobiologists extrapolate from what we’ve seen here on Earth to speculate on what may be out there. Although life “like us” on our sister planets has pretty much been ruled out by decades of robotic space missions, less familiar life – akin to those weird little extremophiles – is another matter.  

 The question of life on Mars has been especially captivating. Today the planet is a virtually airless, frigid desert, but we know it was much warmer and wetter in the past. And the idea that something might still lurk in the Martian soil, protected from the harsh UV radiation that blasts the surface, has never been definitively ruled out. In fact, it’s possible that life originated on Mars, and came to Earth via debris from an asteroid impact, or some other high-energy event – an idea known as “panspermia.” It’s a perfectly plausible idea, Sherwood Lollar says, though “there’s no evidence for or against it.”   

 The reverse is also possible: life may have blasted off our planet and ended up on Mars. Either way, it still leaves the question of how life in the solar system ultimately got started.  

 Meanwhile, astrobiologists are looking for so-called “biosignatures” – unambiguous indicators of biological activity – on other worlds, whether in our solar system or farther afield. And a better understanding of life’s diversity here on Earth is crucial to identifying possible signs of life elsewhere in the universe.  

 Sherwood Lollar also believes that the more we learn about extreme life, the better our chances of grasping how it all began. “Understanding the limits of life inevitably helps us understand something about the origins of life,” she says. Seeing the vast range of environments in which life can take hold, from the ocean’s depths to subterranean groundwater, perhaps even in the clouds above us, “has forced us to be humble,” she says. “There are parts of our planet that we’ve really still only begun to explore.”  

 The search for life’s origins isn’t just an exercise in curiosity. Sherwood Lollar notes that modern vaccines survive only within a limited temperature range, so learning how extremophiles handle very hot or very cold environments may help us design more durable vaccines.   

 Babaian sees broader applications: The quest to understand life’s origins “will tell us about the fringes of life,” he says, “and I think understanding the fringes of life will give us incredibly important information about human disease and human pathology.”  

 At the end of the day, though, the question of life’s origins captures the imagination because it is something we’ve wondered about since the dawn of science, and certainly since the time of Darwin. Slowly, the picture is coming into focus: We know that complex chemical entities appeared on our planet, and by some sequence of events that we don’t yet fully understand, chemistry gave way to biology – perhaps via a process involving blob-like RNA condensates, if Alan Moses’s hunch is on the right track.   

 Knowing how life began on our planet could ultimately be as profound as learning that the Earth revolves around the sun – or that goldfish and galaxies are both made of atoms. “I think discovering a scientific basis for the origin of life will change how we look at ourselves,” Moses says.