A new study shows that the chemical reactions that can support biology are radically different from life on different planets, using many elements other than carbon, which form the basis of life on Earth. Life on Earth is based on organic compounds. These molecules consist of carbon and often contain other elements such as hydrogen, oxygen, nitrogen, phosphorus and sulfur.

But scientists have long wondered whether extraterrestrial life could develop based on a completely different chemistry. For example, researchers have long suggested that silicon could be the basis of biology.

“It’s important to explore these possibilities so we have an idea of ​​what all life forms, not just life on Earth, might look like,” said study senior author Betül Kachar, an astrobiologist, bacteriologist and evolutionary biologist at the University of California. Wisconsin-Madison.

One type of chemical interaction that is key to life on Earth is known as autocatalysis. Autocatalytic reactions are self-sustaining; They can produce molecules that help repeat the same reaction. Imagine a growing population of rabbits. Pairs of rabbits mate, produce new rabbit babies, and then the new rabbits grow and mate, producing more rabbits. You don’t need too many rabbits to grow nearby.

“One of the main reasons why origins of life researchers are interested in autocatalysis is that reproduction, an important feature of life, is an example of autocatalysis,” Cachar said. “Life catalyzes the education of a new life. One cell produces two cells that can become four, and so on. As the number of cells increases, the number and diversity of possible interactions increases accordingly.”

In a new study, scientists investigated autocatalysis as well as organic compounds. They concluded that autocatalysis may contribute to abiogenesis, that is, the emergence of life from non-living. Scientists focused on ratio loops that can create multiple copies of a molecule. These products can be used as starting materials to help repeat these cycles and lead to autocatalysis.

“Proportionation is probably unique because it’s the only reaction that produces multiples; it’s very similar to reproduction,” the study’s lead author, evolutionary biologist Zhen Peng of the University of Wisconsin-Madison, told Space.com.

To find these responses, scientists analyzed more than two centuries of digitized scientific documents written in different languages. “With powerful language search and translation tools, we were able to develop and conduct this first-of-its-kind assessment of the prevalence of autocatalytic cycles,” said study co-author Zach Adam, a geologist at the University of Wisconsin-Madison. . he told Space.com.

Ultimately, the researchers discovered 270 different autocatalytic reaction cycles. “Autocatalysis may not be that rare, but instead may be a common feature of many different environments, even ones that are truly different from Earth,” Cachar said.

Organic compounds were not used in most of the 270 cycles. Some focused on elements that are not found in life on Earth or are extremely rare, such as mercury or the radioactive metal thorium. A series of cycles probably only occur at extremely high or low temperatures or pressures.

Researchers have even discovered four autocatalytic cycles involving noble gases that only occasionally react chemically with other elements. If even an inert gas such as xenon can participate in autocatalysis, “there is good reason to believe that autocatalysis occurs more readily in other elements,” Peng said.

Only eight of these cycles were relatively complex and consisted of four or more reactions. Most of the 270 cycles were simple, consisting of only two reactions each.

“Such reactions were believed to be very rare,” Cachar said in a statement. “We show that this is actually not uncommon. You just have to look in the right place.”

The researchers noted that it is possible to put together several cycles, even if they are very different from each other. This can lead to self-sustaining chemical reactions that produce a wide variety of molecules and create great complexity.

“With so many basic recipes for autocatalysis in hand, the focus of research can now shift to understanding how autocatalysis through proportionation could have more significant effects in shaping the chemistry of the planet,” Cachar said.

“The cycles presented here are a set of basic recipes that can be mixed and matched in ways that have not been used before on our planet,” Peng said. “They could lead to the discovery of entirely new examples of complex chemistry operating under conditions where carbon- and even silicon-based cycles are depleted or frozen.”

The researchers cautioned that it remains unclear how plausible these cycles are. “There is no guarantee that all the samples we collected can be run in the laboratory or found on other astronomical objects,” Peng said.

In addition to the implications this work could have for finding life in the universe and understanding the origins of life, Adam said this research could also have practical applications such as “optimizing chemical synthesis and efficient use of resources and energy.” “Another is the use of chemical compounds for interesting tasks such as chemical calculations.” Source