These sulfur bacteria haven’t evolved for billions of years.
Credit: UCLA Center for the Study of Evolution and the Origin of Life
Excerpt from natmonitor.com
By Justin Beach
If there was a Guinness World Record for not evolving, it would be held by a sulfur-cycling microorganism found off the course of Australia. According to research published in the Proceedings of the National Academy of Sciences, they have not evolved in any way in more than two billion years and have survived five mass extinction events.
According to the researchers behind the paper, the lack of evolution actually supports Charles Darwin’s theory of evolution by natural selection.
The researchers examined the microorganisms, which are too small to see with the naked eye, in samples of rocks from the coastal waters of Western Australia. Next they examined samples of the same bacteria from the same region in rocks 2.3 billion years old. Both sets of bacteria are indistinguishable from modern sulfur bacteria found off the coast of Chile.
“It seems astounding that life has not evolved for more than 2 billion years — nearly half the history of the Earth. Given that evolution is a fact, this lack of evolution needs to be explained,” said J. William Schopf, a UCLA professor of earth, planetary and space sciences in the UCLA College who was the study’s lead author in a statement.
Critics of Darwin’s theory of evolution might be tempted to jump on this discovery as proof that Darwin was wrong, but that would be a mistake.
Darwin’s work focused more on species that changed, rather than species that didn’t. However, there is nothing in Darwin’s work that states that a successful species that has found it’s niche in an ecosystem has to change. Unless there is change in the ecosystem or competition for resources there would be no reason for change.
“The rule of biology is not to evolve unless the physical or biological environment changes, which is consistent with Darwin. 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.” said Schopf, who also is director of UCLA’s Center for the Study of Evolution and the Origin of Life.
It is likely that there were genetic mutations in the organisms. Mutations are fairly random and happen in all species, but unless those mutations are improvements that help the species function better in the environment, they usually do not get passed on.
Schopf said that the findings provide further proof that Darwin’s ideas were right.
The oldest fossils analyzed for the study date back to the Great Oxidation Event. This event, which occurred between 2.2 and 2.4 billion years ago, saw a substantial increase in Earth’s oxygen levels. That period also saw an increase in sulfates and nitrates, which is all that the microorganisms would have needed to survive and reproduce.
Shopf and his team used Raman spectroscopy, which allows scientists to examine the composition and chemistry of rocks as well as confocal laser scary microscopy to generate 3-D images of fossils embedded in rock.
The research was funded by NASA Astrobiology Institute, in the hope that it will help the space agency to find life elsewhere.