What composes alien life? New study reveals, unlike humans they may not be carbon-based
Study finds self-sustaining chemical reactions that could support alien life forms, beyond Earth's organic compounds.
A groundbreaking study has highlighted the possibility of self-sustaining chemical reactions capable of supporting alien life vastly different from that present on earth. While Earth's biology hinges on organic compounds, comprised mainly of carbon along with elements like hydrogen, oxygen, nitrogen, phosphorus, and sulphur, scientists feel alternative chemical frameworks could give rise to alien life forms.
In this innovative study, scientists sought autocatalytic reactions beyond the realm of organic compounds, speculating that such reactions could have driven abiogenesis, the emergence of life from non-life. They delved in on a specific type of chemical process known as "comproportionation cycles," which can yield multiple copies of a molecule and employ these products as catalysts for the same cycle, effectively achieving autocatalysis.
Autocatalysis, a chemical interaction that perpetuates itself by generating molecules is a concept central to life on our planet. Think of it as a population of rabbits growing exponentially – pairs of rabbits produce litters, and the cycle continues, leading to a proliferation of rabbits.
Betül Kaçar, an astrobiologist, bacteriologist, and evolutionary biologist at the University of Wisconsin-Madison is quoted on space.com explaining that ‘one of the major reasons that origin-of-life researchers care about autocatalysis is because reproduction — a key feature of life — is an example of autocatalysis. Life catalyzes the formation of more life. One cell produces two cells, which can become four and so on. As the number of cells multiply, the number and diversity of possible interactions multiplies accordingly.’
Zhen Peng, an evolutionary biologist at the University of Wisconsin-Madison and the lead author of the study, likens comproportionation cycles to reproduction due to their capacity to generate multiples of an output.
To identify these reactions, researchers analysed over two centuries' worth of digitized scientific literature in various languages, making use of advanced language search and translation tools. The outcome was astonishing: they uncovered 270 different cycles of autocatalytic reactions. These cycles often deviated from the organic compounds typical on Earth, occasionally involving elements like mercury, thorium, and even noble gases such as xenon. Some cycles were conditioned by extreme temperatures or pressures.
Remarkably, even relatively inert gases like xenon participated in autocatalysis. This revelation hinted at the potential prevalence of autocatalysis across a broader spectrum of elements.
Of the 270 cycles discovered, only eight were complex, composed of four or more reactions. The majority consisted of simple, two-reaction cycles, which defied the conventional belief that such reactions are exceedingly rare.
Kaçar noted, "It was thought that these sorts of reactions are very rare. We are showing that it's actually far from rare. You just need to look in the right place."
Researchers suggested that combining multiple cycles, even when starkly different, could generate self-sustaining chemical reactions producing a diverse array of molecules, thus fostering complexity.
Kaçar states a shift in research focus toward understanding how autocatalysis, specifically through comproportionation, shapes a planet's chemistry. The research team anticipates that future experimentation will test the practical applicability of their findings.
The groundbreaking findings were published in the Journal of the American Chemical Society on September 18th.