Scientists find organism that hasn’t evolved in 2.3bn years, proving Darwin right

3 Feb 2015

A section of a 2.3 billion-year-old fossil-bearing rock. The fossils (the dark areas) are essentially identical to ones that are 500 million years younger, and to modern microorganisms that live in seawater mud.

American scientists have discovered the ‘greatest absence of evolution’ ever recorded, in a deep-sea micro-organism found in Western Australia, in an environment unchanged in 3bn years.

The scientists examined sulphur bacteria 1.8bn years old and realised they look identical to bacteria in the same region that’s 2.3bn years old.

Additionally, both sets of ancient bacteria are indistinguishable from modern sulfur bacteria found in mud off the coast of Chile.

The micro-organisms date back to the Great Oxidation Event, which wasn’t as brilliant as it sounds. Between 2.2bn and 2.4bn years ago, Earth’s oxygen levels rose sharply, allowing bacteria like this to flourish and killing off most of the planet’s anaerobic species.

Astounding how little has changed

“It seems astounding that life has not evolved for more than 2bn years — nearly half the history of the Earth,” said J William Schopf, a UCLA professor of earth, planetary and space sciences in the UCLA College and who was the study’s lead author.

Microorganism showing no evolution

A section of a 1.8bn-year-old fossil-bearing rock.

“Given that evolution is a fact, this lack of evolution needs to be explained.”

The explanation lies in Darwin’s theory of evolution, which claims that species adapt and evolve to reflect their changing environment. In this instance, the environment has not changed one bit in 3bn years, which in itself is amazing.

Fits Darwin’s ideas perfectly

“These micro-organisms are well-adapted to their simple, very stable physical and biological environment,” Schopf said. “If they were in an environment that did not change but they nevertheless evolved, that would have shown that our understanding of Darwinian evolution was seriously flawed.”

Schopf said the findings therefore provide further scientific proof for Darwin’s work. “It fits perfectly with his ideas,” he said.


Unchanged over 2bn years. All images via J William Schopf/UCLA Center for the Study of Evolution and the Origin of Life

Gordon Hunt was a journalist with Silicon Republic