Did Life on Earth Start Because of Asteroids?

Asteroids could help explain how life began on Earth, according to a new study from Georgia Tech. Analysis of these bodies supplies researchers with a glimpse of the chemical makeup of the ancient solar system, providing a “jumping off” point to determine how life came into being on our home world.

At the Center for Chemical Evolution at Georgia Tech, researchers believe they have evidence that asteroids contain complex molecules which may have led to the development of life on Earth. These molecules may have developed into amino acids, and then peptides, tiny molecules similar to proteins.  From these prebiotic chemicals, true life could have evolved, the team speculates.

“It’s important for us to study materials from asteroids and meteorites, the smaller versions of asteroids that fall to Earth, to test the validity of our models for how molecules in them could have helped give rise to life. We also need to catalog the molecules from asteroids and meteorites because there might be compounds there that we had not even considered important for starting life,” explained Nicholas Hud, a chemist at Georgia Tech.

Nicholas Hud
Nicholas Hud of Georgia Tech studies the origins of life here on Earth, and how it may have started in outer space. Photo: Georgia Tech / Fitrah Hamid

In popular culture, asteroids are often seen as a menace, threatening widespread damage on Earth, or acting as obstacles to spacecraft flying through space. While they certainly pose hazards to life on our home planet, this new research suggests we may not be here without their influence.

The chemical makeup of asteroids has been studied for decades, as investigators searched for the origins of terrestrial life. Examination of these bodies is the only way to be certain of the composition of materials which fell to Earth before life began.

Since 1952, researchers have run experiments attempting to understand conditions on Earth billions of years in the past. Today, several pathways to life are understood, beginning with simple molecules exposed to conditions similar to those seen in the earliest days of our planet.

For years, geologists and biologists believed that the atmosphere of Earth in its first 500 million years was oxygen-poor, and rich with methane and other reducing gases. New studies suggest, however, that the atmosphere of our planet before life arose may have been more like our present-day atmosphere than previously believed. This finding concerning the oxidation state of the ancient atmosphere would have a significant impact on theories of how life began.

“We can’t even begin to talk about life on Earth until we know what that stage is. And oxygen conditions were vitally important because of how they affect the types of organic molecules that can be formed,” said Bruce Watson, Institute Professor of Science at Rensselaer Polytechnic Institute (RPI).

Despite the atmosphere, the Earth would have looked far different four billion years ago than the planet we see today. Devoid of continents, the vast oceans were punctuated with scattered islands. The Sun was also a different body than the one we know today, producing less light and more cosmic rays than our companion star we see in the modern era.

These conditions, working together, may have provided the setting necessary for chemicals delivered to our home world from asteroids to develop into the living world we know today.

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