Scientists Explain Why Organism Has Not Evolved In More Than 2 Billion Years

Microscopic organisms that are 1.8 billion years old were discovered by an international collaboration of scientists. Amazingly, these sulphur bacteria seem well-preserved in rock formations from Western Australian seas and show no indication of evolution in more than 2 billion years. Prof James William Schopf, paleobiologist at the University of California in Los Angeles, explains that the lack of evolution can be attributed to biological environment that remained unchanged for 3 billion years.

Another set of microbes, which dates back 2.3 billion years ago, were also found in the same area. These ancient microorganisms are very much different from modern sulphur bacteria, discovered more than 8 years ago in South America. Schopf was able to analyse the fossils’ chemistry and composition using Raman spectroscopy.

In another technique, confocal microscopy was used to have a 3-D presentation of the fossils. Analysis shows that the ancient bacteria emerged during the Great Oxidation, an event in which the Earth’s oxygen levels significantly increased billions of years ago. The occurrence also generated great amounts of sulphate and nitrate which nourished and sustained the saltwater microorganisms living in deep sea mud environment.

Schopf, also a director of the Center for the Study of Evolution and the Origin of Life in UCLA, explains that these recent findings supports Charles Darwin’s work on evolution. The microorganisms did not evolve for more than 2 billion years because they lived simply in a sustainable and stable natural environment. He said, “The rule of biology is not to evolve unless the physical or biological environment changes, which is consistent with Darwin … 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."

The stasis of sulfur-cycling ecosystems and its biotic components for more than 2 billion years shows that organisms may not undergo or may have little changes if their environment remains unaltered for a long period. Conversely, if the environment undergoes changes, organisms in it evolve as well. Details on this research are published online on the January issue of the Proceedings of the National Academy of Sciences.