Scientists have discovered a type of deep-sea microorganism that seems to be the exception to the rule of evolution. An international team of researchers say the organism does not appear to have evolved over more than 2 billion years. Even so, the scientists who discovered this anomalous being argue that the organism’s lack of evolution actually still supports the theory of evolution.

sulfur bacteria

Scientists examined sulfur bacteria preserved in rocks from the coast of Western Australia. Those fossils are approximately 1.8 billion years old. The team of researchers compared those samples to bacteria from the same region from 2.3 billion years ago, and the two sets look the same. That fact isn’t necessarily shocking. The earth-shattering discovery came to light when scientists realized that both ancient bacteria samples are identical to modern sulfur bacteria found off the Chilean coast. This finding means that the microorganism hasn’t evolved in more than 2 billion years, or nearly half the history of the Earth.

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According to J. William Schopf, a UCLA professor and lead author of the study, “Given that evolution is a fact, this lack of evolution needs to be explained.” This discovery opens up a world of confusing possibilities for researchers. Is this an indication that the sulfur microorganism has already evolved to perfection? Are there other organisms on earth that have similarly evaded the need to evolve? Will there come a point when other occupants of the planet cease to evolve?

Evolution generally happens after an organism’s environment changes, making evolution necessary for survival. Schopf says the environment in which these particular microorganisms live has remained essentially unchanged for 3 billion years. Without the need to adapt to a changing environment, the bacteria simply did not change.

That actually means this discovery, published in the Proceedings of the National Academy of Sciences, proves Charles Darwin’s theory of evolution perfectly. Just as the theory is supported by evidence of creatures evolving over time to meet the requirements of their changing environs, the absence of change here also fits the criterion. The only notable change to the environment where the sulfur bacteria thrive was the Great Oxidation Event, which likely between 2.2 billion and 2.4 billion years ago. The event produced a dramatic increase in sulfate and nitrate—the only nutrients required for the sulfur bacteria to survive. Adaptation wasn’t necessary, but the increased nutrients allows the microorganisms to multiply and thrive.

Proceedings of the National Academy of Sciences


Images via Shutterstock and Amit Patel.