Where does life on Earth come from?

Life on our planet appeared early in Earth’s history. Because it is a relatively young planet, our Earth does not have many of the chemical components necessary for life to develop. Since prebiotic chemicals such as sugars and amino acids are known to occur on asteroids and comets, it has been suggested that Earth was seeded with life by cometary impacts. and asteroids. While this may have played a role, a new study shows that space dust seeded life on Earth when it was quite young, and that may have made a difference.

We have long known that cosmic dust accumulated on early Earth, but it was not considered a major source for life because of the way it accumulated. With comet and asteroid impacts, many protozoans are present at the impact site. On the other hand, dust is scattered across the Earth’s surface instead of accumulating locally. However, the authors of the new study suggest that cosmic dust can accumulate and concentrate in sediments, and want to find out how that might have played a role in the initial appearance. of life on land.

Using estimates of the rate of cosmic dust accumulation during the early Earth and computer simulations of how dust might have accumulated in sediments over time, the team looked at the concentration levels. middle of the sediments that can form.

One of the things they found is that while comet impacts may produce local increases in prebiotic substances, the amount of cosmic dust deposited is much higher. They also found that the melting and freezing of glaciers can significantly increase the concentration of chemicals from dust.

For example, for early-formed subglacial lakes, concentrations of prebiotic chemicals from dust would be much higher than concentrations at impact sites. This means that cosmic dust could play a much larger role in the emergence of life than impacts.

There is still much we have to learn about early life on Earth and how life might have arisen from prebiotic substances, but it is clear that life on Earth could only exist thanks to prebiotic substances. chemistry outside the Earth.