Scientists have long pondered how life began on Earth, with various theories pointing to deep-sea vents, electric sparks, or a chemical big bang.
But new evidence gathered from a near-Earth asteroid bolsters one of the simplest explanations: microorganisms hitched a ride on a space rock and set up residence after it crashed to Earth billions of years ago.
In this case, researchers found two organic compounds essential for living organisms on an asteroid named Ryugu. The Japanese Space Agency’s Hayabusa2 spacecraft collected rocks from two sites on Ryugu in 2019. Analysis of the rocks found niacin, more widely known as Vitamin B3, and uracil, a chemical building block for RNA, the molecules that carry the directions for building organisms.
“The present study strongly suggests that such molecules of prebiotic interest commonly formed in carbonaceous asteroids including Ryugu and were delivered to the early Earth,” scientists wrote in their March 21 report in Nature Communications.
The Ryugu samples appear simply as dark-gray rubble and were brought 250 million kilometers back to Earth for study. They dropped to the planet’s surface in a sealed capsule in 2020 in Australia’s remote outback, and were transported to Japan for analysis, The Associated Press reported.
“Our key finding is that uracil and niacin, both of which are of biological significance, are indeed present in extraterrestrial environments and they may have been provided to the early Earth as a component of asteroids and meteorites,” Yasuhiro Oba, astrochemist and lead author, told The AP. “We suspect they had a role in prebiotic evolution on Earth and possibly for the emergence of first life.”
Theories of life’s origins
The theory of life arriving on Earth from asteroids isn’t new. Similar compounds have been found in space rocks that crashed on the planet’s surface. But it was always possible that the discoveries were the result of contamination.
The new research proves that these compounds exist in space and could have traveled to Earth in the distant past. But of course, that leads to another inevitable question: Where did those compounds come from?
According to the research, the organic matter found on Ryugu may have formed through chemical reactions caused by starlight on icy materials common in interstellar space.
So now we have a little more proof that Neil deGrasse Tyson is correct in saying humans are made from the stuff of stars:
“We are stardust brought to life, then empowered by the universe to figure itself out —and we have only just begun.”
