The idea that life began as clay crystals is 50 years old

In 1966, a young chemist suggested a radical new theory for how life might have begun on Earth. Fifty years on, we ask if there was any truth in his ideas

A rock is the ultimate example of inanimate, dead matter. After all, it just sits there, and only moves if it is pushed. But what if some minerals are not as stone-dead as we thought?
Chemist Graham Cairns-Smith has spent his entire scientific career pushing a simple, radical idea: life did not begin with fiddly organic molecules like DNA, but with simple crystals.
It is now 50 years since Cairns-Smith first put forward his ideas about the origin of life. Some scientists have ridiculed them; others have, cautiously or wholeheartedly, embraced them. They have never become mainstream orthodoxy, but they have never quite gone away either. Was there any truth to Cairns-Smith’s daring proposal? Did life really come from crystals?
In June 2016 I visited Cairns-Smith and his wife Dorothy at their house on the outskirts of Glasgow, UK. Now 85, he has a rare condition related to Parkinson’s disease, which has affected his mobility. However, his scientific curiosity and his sense of humour remain undimmed.
He was a dour man and he sort of muttered, ‘A pity you chose science’
While he will most likely be remembered for his theories on the origin of life, his first passion was painting.
“We met when he was at Glasgow and he was doing these,” says Dorothy, showing me the prolific collection lining almost every wall in the downstairs of their house. “He was going through an abstract phase.”
Cairns-Smith’s success as a painter eventually became too demanding. He was putting on one-man shows and getting paintings into the Royal Scottish Academy, but decided to quit and focus on science, which offered a more reliable income with which to support a family.
“There was a man called William Crosbie, who was a very well-known Scottish painter, who was teaching him [at Glasgow],” Dorothy recalls. “He was a dour man and he sort of muttered, ‘A pity you chose science’.”
However, Cairns-Smith does not seem to have any regrets about his decision. Copies of his scientific books, and the sketches he drew to illustrate them, are spread across his upstairs study. They have just as much of a presence in the house as his artwork.
As a student at the University of Edinburgh in the 1950s, Cairns-Smith became fascinated by the problem of how life began.
Through his studies of organic chemistry, Cairns-Smith understood that the essential molecules of life – such as DNA and proteins – could be delicate and temperamental. So how could complex molecules like these spring from the soup of simple compounds on the primordial Earth? This puzzle still occupies scientists today.
To Cairns-Smith, the experiment raised more questions than it answered
In a study published in 1953 – the same year that the structure of DNA was discovered – a biochemist called Stanley Miller sent a bolt of electricity through a mixture of gases and liquids thought to have been present on the early Earth. The spark turned these simple chemicals into some of the most basic building blocks of life: amino acids, the units that link together to make proteins.
The story hit the headlines. “Science: Semi-creation” was the headline in Time magazine. Miller’s study became a landmark scientific paper.
But to Cairns-Smith, the experiment raised more questions than it answered.
Although Miller had made some of the most essential compounds of life, his experiment did not explain how they and other building blocks – such as nucleotides, which make up DNA – first came together in an ordered way, to form the complex molecules necessary for life.
His aim was to find a system much simpler than modern life
In Miller’s experiment, “simpler molecules are more likely to be found and more likely to form than more complex molecules,” says Cairns-Smith. “The idea you’d make a nucleotide is ridiculous. The more complicated the molecule, the less of it will form.”
For Cairns-Smith, this was the real problem. He thought there had to be another stage before our elaborate system of genetic material took over.
“It was an extremely interesting experiment,” says Cairns-Smith. He also describes it as “beautiful”. But it did not satisfy his curiosity.
So he decided to go back to basics.
Cairns-Smith asked himself two questions: What are the essential properties needed for a living system, and can those properties be found anywhere other than the forms of life that we know today?
If you look at clay under a microscope, you will find that it is made of tiny crystals
His aim was to find a system much simpler than modern life, but which had some of the crucial properties of a living system. He found an answer in an unlikely place: clays.
Most of us, if we think about clay at all, probably just remember how bad we were in pottery class at school. Clay, at first glance, is just a sort of damp, vaguely gritty dirt.
But Cairns-Smith knew there was more to clay than that. In an abstract way, it can be rather life-like.
If you look at clay under a microscope, you will find that it is made of tiny crystals. Within each crystal, atoms are arranged in a structure that repeats in a tightly-packed, regular pattern.
Crystals’ essential characteristics mean they are primed to begin evolving
Each crystal can grow, if it is placed in water laced with the same chemical components. Crystals can also split apart, with one “mother” crystal giving rise to “daughter” crystals.
Each crystal can even have its own peculiarities, which it can pass on to its daughter crystals – much like living things inherit traits from their parents. And sometimes, when a crystal breaks apart, new quirks can be introduced, for instance because of the stress of breaking. This is similar to the process of genetic mutation, which creates new traits in living things.
In other words, Cairns-Smith reasoned, crystals’ essential characteristics mean they are primed to begin evolving.
When a crystal passes its peculiarities onto its daughters, these unique traits could either help or hinder the new crystals.
For instance, the daughters may end up more likely to be able to split into two crystals. If the characteristics of a crystal affect its ability to split apart, then in effect that crystal has an evolutionary advantage.
In 50 years there have only been a handful of experiments exploring Cairns-Smith’s ideas
In a sense, physical flaws or peculiarities in a crystal could be thought of as genetic information. As a result, Cairns-Smith thought that crystal minerals could be subject to a simple form of evolution by natural selection. This idea is now called the “crystals-as-genes hypothesis”.
At a later stage, Cairns-Smith reasoned, biological molecules like DNA began to associate with the crystals. This helped the replication process. Eventually, a “genetic takeover” happened: the biological molecules developed the ability to replicate by themselves, and left the crystals behind.
Cairns-Smith set all this out in a paper published in 1966, half a century ago.
His ideas are elegant, but there is a big problem: they have proved almost impossible to test. In 50 years there have only been a handful of experiments exploring Cairns-Smith’s ideas.
The trouble is that there is no experimental technique for studying minerals at the tiny scales necessary to examine the processes Cairns-Smith outlined, says Dieter Braun of Ludwig Maximilian University of Munich in Germany.
I fell in love with the book because it was so unlike a typical scientific monograph
Researchers would have to minutely examine nanoscale crystals, underwater, over a period of days to monitor how they behave. “That’s just technologically very difficult,” Braun says.
He says we would need something analogous to genetic sequencing, the method by which researchers “read” the letters of DNA that make up the human genome. “You know, it took us 40 years to get sequencing for a molecule like DNA really working fast,” says Braun.
Braun adds that geneticists had a powerful motivation to perfect DNA sequencing: it promised new medical treatments. Studying clay crystals would be equally difficult and expensive, with no practical benefit.
Even so, at least one element of Cairns-Smith’s hypothesis has been put to the test.
Bart Kahr is a crystallographer at New York University in the US. He first discovered Cairns-Smith’s ideas when he came across one of his books in a shop in the mid-1980s.    
He wanted to track how mother crystals pass on their traits to daughter crystals
“I fell in love with the book because it was so unlike a typical scientific monograph,” says Kahr. “It was so impossibly rich [in] genuinely new ideas, and it was written in a kind of a literary vein, almost.”    — BBC

The idea that life began as clay crystals is 50 years old

In 1966, a young chemist suggested a radical new theory for how life might have begun on Earth. Fifty years on, we ask if there was any truth in his ideas

A rock is the ultimate example of inanimate, dead matter. After all, it just sits there, and only moves if it is pushed. But what if some minerals are not as stone-dead as we thought? Chemist Graham Cairns-Smith has spent his entire scientific career pushing a simple, radical idea: life did not begin with fiddly organic molecules like DNA, but with simple crystals. It is now 50 years since Cairns-Smith first put forward his ideas about the origin of life. Some scientists have ridiculed them; others have, cautiously or wholeheartedly, embraced them. They have never become mainstream orthodoxy, but they have never quite gone away either. Was there any truth to Cairns-Smiths daring proposal? Did life really come from crystals? In June 2016 I visited Cairns-Smith and his wife Dorothy at their house on the outskirts of Glasgow, UK. Now 85, he has a rare condition related to Parkinsons disease, which has affected his mobility. However, his scientific curiosity and his sense of humour remain undimmed. He was a dour man and he sort of muttered, A pity you chose science While he will most likely be remembered for his theories on the origin of life, his first passion was painting. We met when he was at Glasgow and he was doing these, says Dorothy, showing me the prolific collection lining almost every wall in the downstairs of their house. He was going through an abstract phase. Cairns-Smiths success as a painter eventually became too demanding. He was putting on one-man shows and getting paintings into the Royal Scottish Academy, but decided to quit and focus on science, which offered a more reliable income with which to support a family. There was a man called William Crosbie, who was a very well-known Scottish painter, who was teaching him [at Glasgow], Dorothy recalls. He was a dour man and he sort of muttered, A pity you chose science. However, Cairns-Smith does not seem to have any regrets about his decision. Copies of his scientific books, and the sketches he drew to illustrate them, are spread across his upstairs study. They have just as much of a presence in the house as his artwork. As a student at the University of Edinburgh in the 1950s, Cairns-Smith became fascinated by the problem of how life began. Through his studies of organic chemistry, Cairns-Smith understood that the essential molecules of life such as DNA and proteins could be delicate and temperamental. So how could complex molecules like these spring from the soup of simple compounds on the primordial Earth? This puzzle still occupies scientists today. To Cairns-Smith, the experiment raised more questions than it answered In a study published in 1953 the same year that the structure of DNA was discovered a biochemist called Stanley Miller sent a bolt of electricity through a mixture of gases and liquids thought to have been present on the early Earth. The spark turned these simple chemicals into some of the most basic building blocks of life: amino acids, the units that link together to make proteins. The story hit the headlines. Science: Semi-creation was the headline in Time magazine. Millers study became a landmark scientific paper. But to Cairns-Smith, the experiment raised more questions than it answered. Although Miller had made some of the most essential compounds of life, his experiment did not explain how they and other building blocks such as nucleotides, which make up DNA first came together in an ordered way, to form the complex molecules necessary for life. His aim was to find a system much simpler than modern life In Millers experiment, simpler molecules are more likely to be found and more likely to form than more complex molecules, says Cairns-Smith. The idea youd make a nucleotide is ridiculous. The more complicated the molecule, the less of it will form. For Cairns-Smith, this was the real problem. He thought there had to be another stage before our elaborate system of genetic material took over. It was an extremely interesting experiment, says Cairns-Smith. He also describes it as beautiful. But it did not satisfy his curiosity. So he decided to go back to basics. Cairns-Smith asked himself two questions: What are the essential properties needed for a living system, and can those properties be found anywhere other than the forms of life that we know today? If you look at clay under a microscope, you will find that it is made of tiny crystals His aim was to find a system much simpler than modern life, but which had some of the crucial properties of a living system. He found an answer in an unlikely place: clays. Most of us, if we think about clay at all, probably just remember how bad we were in pottery class at school. Clay, at first glance, is just a sort of damp, vaguely gritty dirt. But Cairns-Smith knew there was more to clay than that. In an abstract way, it can be rather life-like. If you look at clay under a microscope, you will find that it is made of tiny crystals. Within each crystal, atoms are arranged in a structure that repeats in a tightly-packed, regular pattern. Crystals essential characteristics mean they are primed to begin evolving Each crystal can grow, if it is placed in water laced with the same chemical components. Crystals can also split apart, with one mother crystal giving rise to daughter crystals. Each crystal can even have its own peculiarities, which it can pass on to its daughter crystals much like living things inherit traits from their parents. And sometimes, when a crystal breaks apart, new quirks can be introduced, for instance because of the stress of breaking. This is similar to the process of genetic mutation, which creates new traits in living things. In other words, Cairns-Smith reasoned, crystals essential characteristics mean they are primed to begin evolving. When a crystal passes its peculiarities onto its daughters, these unique traits could either help or hinder the new crystals. For instance, the daughters may end up more likely to be able to split into two crystals. If the characteristics of a crystal affect its ability to split apart, then in effect that crystal has an evolutionary advantage. In 50 years there have only been a handful of experiments exploring Cairns-Smiths ideas In a sense, physical flaws or peculiarities in a crystal could be thought of as genetic information. As a result, Cairns-Smith thought that crystal minerals could be subject to a simple form of evolution by natural selection. This idea is now called the crystals-as-genes hypothesis. At a later stage, Cairns-Smith reasoned, biological molecules like DNA began to associate with the crystals. This helped the replication process. Eventually, a genetic takeover happened: the biological molecules developed the ability to replicate by themselves, and left the crystals behind. Cairns-Smith set all this out in a paper published in 1966, half a century ago. His ideas are elegant, but there is a big problem: they have proved almost impossible to test. In 50 years there have only been a handful of experiments exploring Cairns-Smiths ideas. The trouble is that there is no experimental technique for studying minerals at the tiny scales necessary to examine the processes Cairns-Smith outlined, says Dieter Braun of Ludwig Maximilian University of Munich in Germany. I fell in love with the book because it was so unlike a typical scientific monograph Researchers would have to minutely examine nanoscale crystals, underwater, over a period of days to monitor how they behave. Thats just technologically very difficult, Braun says. He says we would need something analogous to genetic sequencing, the method by which researchers read the letters of DNA that make up the human genome. You know, it took us 40 years to get sequencing for a molecule like DNA really working fast, says Braun. Braun adds that geneticists had a powerful motivation to perfect DNA sequencing: it promised new medical treatments. Studying clay crystals would be equally difficult and expensive, with no practical benefit. Even so, at least one element of Cairns-Smiths hypothesis has been put to the test. Bart Kahr is a crystallographer at New York University in the US. He first discovered Cairns-Smiths ideas when he came across one of his books in a shop in the mid-1980s. He wanted to track how mother crystals pass on their traits to daughter crystals I fell in love with the book because it was so unlike a typical scientific monograph, says Kahr. It was so impossibly rich [in] genuinely new ideas, and it was written in a kind of a literary vein, almost. BBC