Soapbox Science 2026

Probably nothing has fascinated humankind more, across different cultures, historical eras, and religions, than the big questions about life itself: Where do we come from? Where did it all begin?

A multitude of explanations have been proposed over time. From Aristotle’s idea that life could arise spontaneously from non-living matter to classical creationism, where God, a divine entity formed life and humankind by will.

The idea of genetic evolution is relatively new in the history of origins-of-life-theories. Charles Darwin published Origins of Species in 1859, more than 2000 years after Aristotle’s death. Only since Darwin, has it become generally accepted that life evolved slowly over millions and millions of years of trial and error.

When discussing life, we should probably first define what we actually mean by the term. And there is no simple answer to this. The definitions may vary, even within the scientific community, depending on whom we ask. But let’s start with a practical one. When searching for extraterrestrial life, NASA uses the working definition: “a self-sustaining chemical system capable of Darwinian evolution”.

Let’s break this down. “Self-sustaining” implies that the system must be able to survive in an environment by using resources from its surroundings. Some processes might already meet these criteria, even though we wouldn’t necessarily define them as life. A fire for example, sustains itself by consuming oxygen from the atmosphere and converting it to carbon dioxide, while releasing energy in the process.

What about the second part of the definition “capable of Darwinian evolution”? This implies that the system must be able to undergo changes and be able to remember them. In other words, it needs a form of memory. This is essentially what our genome provides. By passing genetic information to subsequent generations, while allowing for small variations, life has been able to persist across a wide range of environments. Therefore, any early life form would have required some type of hereditary memory. A popular theory building on this idea is the RNA world
hypothesis.

In 1986, the RNA world hypothesis was proposed by Walter Gilbert following the discovery of Ribozymes. Ribozymes are molecular machines that perform a variety of important functions in the body. Their key functional component is made up of RNA. This discovery provided the foundation for the hypothesis. Like DNA, RNA can store genetic information, but it can also perform functional roles, like helping other reactions happen. For origin of life research this means they might be able to self-replicate without further help from other molecules. The RNA
world hypothesis proposes that simple, self-replicating RNA systems were the precursors to all life on earth.

Recalling our definition from earlier, we can put this to a test. Such systems are clearly chemical in nature. Moreover, they are capable of self-replication using building blocks from their environment. Through small errors during replication – mutations – they can evolve under selective pressure. In essence, they fulfill the necessary conditions for a primitive life-like system.

If at this point you feel a bit confused and find yourself thinking: “What exactly is a life-like system” or “Why not just call it life?” – I get you. After all, it’s not that clear cut.

A bunch of self-replicating molecules doesn’t immediately seem alive. Perhaps it isn’t. We may simply call it a replicator. But what if such a system was enclosed within a membrane? Would you then call it a cell? Cells are certainly alive. But what if it still couldn’t move? Does it have memory? Not in the way we typically think about it.

Fact is, the boundaries are blurred. While some might call this a weakness in definition, I would rather view it as a useful flexibility, depending on what your research question is. These stages represent small steps along the path to life in the form we know it today. I think it illustrates beautifully how life is an emergent property of biological systems – something that arises gradually along the way, not some special ingredient, which was just added at some point.

To me, there is something incredibly powerful about the thought that, despite all odds, life happened. Even if the probability is infinitesimally small, in an infinite universe there are infinitely many chances, and eventually this cancels out to one. As a researcher I get to discover how the odds played together in this one special instance. And I couldn’t be more grateful to be part of this magic and experience all that life on this planet can offer.