Bacteria's Lack of Evolution Eludes Scientists

Lying in deep-sea sediments are bacteria that have remained unchanged for the last two billion years, and this lack of evolution - the largest ever reported - is eluding scientists, new research says.

From rocks located in deep-sea waters off the coast of Western Australia, a team from the University of California, Los Angeles (UCLA) collected fossilized sulfur bacteria that was 1.8 billion years old and compared it to bacteria that lived in the same region 2.3 billion years ago.

You would think that after years of evolution - an idea pioneered by scientist Charles Darwin - these ancient bacteria would look different; however, that was not the case. The researchers found that both sets of microorganisms were virtually indistinguishable from modern sulfur bacteria found in mud off of the coast of Chile.

"It seems astounding that life has not evolved for more than 2 billion years - nearly half the history of Earth," study lead author J. William Schopf from UCLA said in a statement. "Given that evolution is a fact, this lack of evolution needs to be explained."

Despite appearances, these microorganisms are actually in line with Darwin's theory of evolution. That's because according to the theory, a species won't evolve unless its physical or biological environment changes. And in the case of sulfur bacteria, their deep-sea environment has remained essentially unchanged for three billion years.

"These microorganisms are well-adapted to their simple, very stable physical and biological environment. 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 explained.

And according to the study, these microorganisms have persisted for millions of years because of the Great Oxidation Event, which occurred between 2.2 and 2.4 billion years ago. This event produced a dramatic increase in sulfate and nitrate - the only nutrients the microorganisms would have needed to survive.

So while sulfur bacteria seem like they're millions of years behind, it appears that they know exactly what they're doing.

The results are described further in the journal Proceedings of the National Academy of Sciences.

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