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A dose of poison could have been the catalyst for life on Earth, according to scientists.

What happened on Earth 4 billion years ago that gave rise to life?  Some scientists think that meteor impacts may have yielded important molecules.  NASA's Goddard Space Flight Center Conceptual Image Lab

What happened on Earth 4 billion years ago that gave rise to life? Some scientists think that meteor impacts may have yielded important molecules.
NASA’s Goddard Space Flight Center Conceptual Image Lab

Cyanide may have played a vital role in the evolution of life on our planet.

If you mix a teaspoon of carbon with a pinch of hydrogen and a pinch of sodium cyanide, you might get a hint about how the basic building blocks of life are formed. That’s right; you read that right. Cyanide

Throughout history, cyanide has earned a well-deserved reputation as a highly deadly poison with devastating effects. Its use as a biological weapon dates back to the Franco-Prussian War at the end of the 19th century and continued through both World Wars, with some evidence that it played a role in the Iran-Iraq War in the 1990s. It has even made its way into popular culture as evidenced by the famous spy movie theme of providing secret agents envisioning a decision between treason and death involving them.

However, in a paper published Thursday in the journal Nature, a group of scientists argue that while cyanide is considered the end of life as we know it, it may have played a role in the evolution of life since the beginning. from the earth. 4 billion years ago. The world looked very different then. Oxygen, for example, which we take for granted, did not yet exist.

“Cyanide is toxic to the kind of life we ​​work with today,” said Ramanarayan Krishnamurthy, a scientist at the Scripps Research Institute in California and the study’s lead author. “Cyanide is toxic to the types of biology we work with today.” However, if biology understands how to deal with it, it may not be toxic.

To do this in the lab, he and his colleagues essentially mixed many compounds present on early Earth and then added some cyanide to the mix.

Ironically, the potentially dangerous substance aided the synthesis of the most fundamental components of life – under mild reaction conditions and with a limited number of steps. Everything turned out to be very simple. According to Krishnamurthy, the fact that something is so easy can be scary at times. To make sure we got the correct interpretations, we had this verified by three or four separate people.

Using its unique mechanism, the team claims to have created the “first-ever demonstration” of this kind of biological pathway to the origin of life — and one that’s much simpler than its widely accepted, non-toxic counterpart, which requires extreme reaction conditions. , complex steps and a healthy dose of faith.

In reality, what happened 4 billion years ago.

Do you remember “primordial soup,” the buckets of various compounds that once roamed freely in Earth’s early oceans? That was something we learned about in science class.

According to experts, this elemental stew propelled molecules to combine and form complex compounds, which then mixed and, many stages later, resulted in the formation of primitive creatures. All that material manifested as us a long (long) time after.

A crucial part of this deepening is the reductive tricarboxylic acid cycle, also known as the r-TCA cycle (get ready for a bite). Proteins are used in this eight-step biological process to make molecules necessary for the existence of life. For the most part, it’s thought to be important to life now, leading researchers to believe it was essential to life long ago, too, when it flew into the primordial soup.

There’s a problem, though: Earth’s early atmosphere was not conducive to the development of r-TCA. When our planet was younger, there was no oxygen, nor were the proteins that help move the cycle forward. Scientists often argue that certain metals may have started things rolling, but that this required extreme conditions, such as extremely high temperatures. And I mean that in the most extreme sense.

To the point where not only are such conditions unlikely to have existed on early Earth, but they also hinder scientists from replicating ancient r-TCA step-by-step in a lab, Krishnamurthy said. Chemists have to assemble everything haphazardly, apply the conditions and then wait.

Although such tests lead to the production of r-TCA molecules, it is difficult to demonstrate that they come out of the cycle. Essentially, the question is whether r-TCA occurred 4 billion years ago, as previously believed.

In an effort to illustrate another reductive cycle that produces the building blocks of life, Krishnamurthy conducted the experiment using cyanide instead of the problematic metals in the original experiment. Surprisingly, he found that step-by-step the molecules followed the same course as r-TCA, but with less general stages and under significantly milder conditions compared to the drug.

It seemed to explain the story of the origin of life on Earth in a considerably simpler way.

Despite this, the researchers cautioned that their findings should be interpreted with caution. For example, according to Krishnamurthy, “cyanide is believed to have been present on early Earth, but there is no direct evidence to support this claim, as it is a highly reactive molecule that may have been eaten.”

Biology has a long and illustrious history.

However, the team’s achievements serve to clarify Krishnamurthy’s philosophy: “What biology is doing today is what biology is doing today.” There is no need to use the same principles on which biology was based 4 billion years ago.

Krishnamurthy uses an excellent illustration to explain how to understand the concept.

Stel je voor dat je iemand uit een afgelegen stad stuurt die alleen huizen kan bouwen van bakstenen en een paar bouwvakkers naar New York City, waar ze met open armen zouden worden ontvangen. Toen ze de wolkenkrabbers zagen, waren ze verbaasd en hebben ze je misschien gevraagd hoe deze massieve metalen constructies mogelijk zijn opgetrokken.

Wat ze vergeten is dat deze wolkenkrabbers niet van bakstenen zijn gebouwd, en zeker niet door een klein aantal bouwvakkers. Ze werden gemaakt van staal met behulp van kranen en andere grote machines. Op dit moment kijken we naar biologie, wat deze enorme, prachtige architectuur is, “legde Krisnamurthy uit. We weten echter niet hoe het werd gebouwd of wat er was voordat het plaatsvond, waardoor het kon plaatsvinden plaats.

If there was enough cyanide on early Earth, it’s possible that life owed its existence to the substance we now recognize as poison. And if we go even further, if aliens exist on other planets, it’s possible that cyanide played a role in their development.

“We’re listening to what the chemistry has to say,” Krishnamurthy explained. “Instead of assuming we already know what biology should have been 4 billion years ago, let’s assume we don’t know.”