Over 4 billion years ago the young and barren Earth was being buffeted by meteor strikes, and that violent bombardment could have created the first amino acids that then gave rise to the origin of life on the planet, a new study suggests.
The hellish temperatures and pressures generated when an extraterrestrial object strikes Earth at speeds of several kilometers per second are enough to shatter and vaporize rock.... Yet part of such an immense burst of energy can trigger chemical reactions that generate complex organic substances from basic inorganic ingredients, says Takeshi Kakegawa [Science News].
Previously, researchers have suggested that organic molecules may have been created elsewhere in the universe and were brought to Earth by meteors. But the new study, in which researchers simulated the impact of meteorites in the primordial ocean, argues that the organic molecules could have been synthesized from the inorganic molecules already present on the planet when the meteorites crashed into the ocean. Other researchers have suggested similar processes for the creation of organic molecules on Earth, including lightning strikes or chemical reactions surrounding hot, volcanic vents in the deep sea. In the study, published in Nature Geoscience [subscription required], the researchers
fired meteorite-like balls of iron and carbon into a mixture of water and ammonia, meant to resemble the oceans billions of years ago. In the experiment, the researchers found that the iron and carbon were heated by the impact and reacted with hydrogen and nitrogen to form biomolecules, including fatty acids, amines and the amino acid glycine [Cosmos Online].
Amines are the building blocks for more complex amino acids, and fatty acids are found in cell membranes. While experts describe the results as plausible, the research hasn't won over everyone.
"It's neat to show that you could harness the energy of impacts to create organic bonds," says Jennifer Blank, an astrobiologist at the SETI Institute in Mountain View, Calif. But she fears that theories of life's origin may never move beyond the hypothetical. "As someone in the general field, one of the frustrations, of course, is that we're never going to know the answer," she says. "But as another mechanism for contributing to the inventory of organic compounds, this is cool" [Scientific American].
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