Microbes Rock
A very old rock — or rather, what’s inside of it —might force scientists to rewrite what we know about the evolution of life on Earth.
As detailed in a new study published in the journal Microbial Ecology, scientists discovered living microbes sealed inside a 2-billion-year-old stone.
It’s “the oldest example of living microbes being found within ancient rock so far discovered,” according to a press release.
“We didn’t know if 2-billion-year-old rocks were habitable,” said lead study author Yohey Suzuki, an associate professor in the Graduate School of Science at the University of Tokyo, in a statement. “Until now, the oldest geological layer in which living microorganisms had been found was a 100-million-year-old deposit beneath the ocean floor, so this is a very exciting discovery.”
In a sense, the rock is something of a time machine. Our current scientific understanding is that the earliest life on Earth emerged about 3.5 billion years ago. Humans, in comparison, have only been around for a few hundred thousand years or so.
As the researchers write in their study, the microbes, which were confirmed to be indigenous to the stone, appear to have evolved incredibly slowly over time. That means further study into the newly unearthed organisms’ genetic makeup could reveal unprecedented insights.
“By studying the DNA and genomes of microbes like these,” said Suzuki, “we may be able to understand the evolution of very early life on Earth.”
Inward, then Outward
The ancient stone was discovered in South Africa’s Bushvelt Igneous Complex by way of ultradeep drilling.
The international coalition of scientists believes that further study of the rock’s microbial community could have repercussions for ongoing research into life on other planets as well.
A key objective of NASA’s Perseverance mission is to retrieve physical samples from Mars. As the study authors note, those specimens will likely be of similar age to the Earthly stone that was just cracked open, making this discovery akin to a test run for interplanetary microbial science.
“Finding microbial life in samples from Earth from 2 billion years ago and being able to accurately confirm their authenticity makes me excited for what we might be able to now find in samples from Mars,” said Suzuki in a statement.
More on surprising things inside of rocks: Microplastics Found in Sediment Layers Untouched by Modern Humans
