There are endless ideas and theories about the origin of life, but they have not yet led to a conclusive, evidence-based explanation. As a result, all kinds of secondary questions still remain unanswered. Such as the question of a reader who writes: “Was the origin of life a one-time event or does new life still arise spontaneously?”
A good question at a good time, responds Dr Alex Blokhuis, postdoctoral researcher within the oLife program (Origins and Evolution of Life) at the University of Groningen. “The correct and honest answer is of course that we don’t know yet, but if you had asked this question ten years ago, the answer from scientists would probably have been unanimous that it worked once and that life can now absolutely no longer arise spontaneously. .”
There is now a more nuanced view on this. Not because we now suddenly know what’s going on, says Blokhuis, but because we increasingly realize that the scientific knowledge that has been accumulated is not sufficient to draw such a firm conclusion. “In other words, we no longer have a good excuse to say that life doesn’t still arise. We are more actively questioning all kinds of common assumptions and I see that as progress.”
But where do those bold claims come from? According to Blokhuis, many assumptions have been made over the years that were initially recognized as assumptions, but have been repeated so often and sometimes actively promoted by Big Names in science that they gradually grew into ‘facts’. “During my PhD research I went through a lot of old articles to see what scientists have claimed, researched and concluded about the origin of life and then it turns out that there are a lot of unfounded assumptions. There’s no evidence for it at all. You can learn a lot just by going back to the scientific literature.”
Sulphurous mud pool at Solfatara, an active volcano near Naples. Did the first life originate in such a warm pool full of ‘primordial soup’?
One of those common assumptions is that uncontrolled chemical reactions always lead to a mess. If you let go of the chemistry you end up with ‘caramel’; an unworkable, unstructured lump in which nothing is possible anymore. Certainly no such thing as life, which is well organized. Blokhuis: “That is a frequently heard argument. But the honest answer is that we don’t really know what exactly happens in such a complicated mixture. It is very well possible that phase separation occurs, for example because certain substances together form a droplet or a bubble. Then you get very different conditions locally and it provides organization and structure.”
Another old argument that comes up often is the alleged rarity of autocatalysis – that is, the phenomenon that molecules enable and accelerate their own formation. That is also an important next step towards the selection of certain molecules, because those who can make more of themselves, beat other molecules that cannot and therefore have a better chance of continuing to exist.
“However, the prevailing view is that autocatalysis is something very special that hardly ever occurs in nature,” says Blokhuis. And so the chance that life still arises spontaneously is nil. “But to see and recognize something, you have to be open to it. We now know from other chemical research areas that are not concerned with the origin of life but with catalysis that autocatalysis is not that rare at all.”
The information carriers of life: RNA and DNA. According to supporters of the ‘RNA world’ theory, it all started with RNA. But hard evidence is lacking and the theory also has many opponents.
Chemistry always gets messy. Autocatalysis is necessary, but rare. And then there are also practical arguments that are often put forward, such as ‘if life were to arise again, it will immediately be eaten by existing life, so we will never find it anyway’. According to Blokhuis, these are all easy stories to get rid of the nagging.
But how does he think we’ll arrive at better answers? “Actually, we should all, ie everyone who works on the origin of life, once again make an inventory of everything that has been devised, researched and published and look at it with an open mind. What are solid conclusions, what evidence is there, what assumptions are completely unsubstantiated, et cetera. So that we get a better grip on what we do and don’t know and can determine how we can expand our knowledge. If you really want to move forward, you only have to rely on things that you can prove.”
In addition, other scientific research has of course not stood still. Many new techniques and methods have been developed within chemistry and physics that can also help origin-of-life research. “We can now research, calculate and predict much more when it comes to complex systems.” And then there is the arrival of a relatively large group of young researchers interested in this field. Blokhuis: “The breath of fresh air is good, there will be more room for new insights and a skeptical approach to the prevailing views. There is more room for criticism and that is profit.”
Hydrothermal vent in the ocean floor at the Mariana Trench. Did the first life originate at such a source? A lot of experimental research is being done on this, but there is no real evidence here either.
Source: Kennislink by www.nemokennislink.nl.
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