In the muddy sediments beneath the deep sea, scientists have found ancient communities of bacteria that have remained virtually unchanged for 2.3 billion years. Researchers say these microscopic organisms are an example of "extreme evolutionary stasis" and represent the greatest lack of evolution ever seen.
They may also, paradoxically, prove that Darwin’s theory of evolution is true. "If evolution is a product of changes in the physical and biological environment, and there are no changes in the physical and biological environment, then there will be no evolution," said J. William Schopf, a paleobiologist at UCLA.
He calls it the null hypothesis required of Darwin’s equation. In a paper published this week in PNAS, Schopf and his colleagues describe three distinct communities of the deep sea microbes separated from each other in time by hundreds of millions of years.
The first is a fossilized community found in 2.3-billion-year-old rock in Western Australia. The second fossilized community was discovered in 1.8-billion-year-old rock, also from Western Australia. The third is a living community discovered in the last decade in sediments off the west coast of South America.
The researchers say that despite their vast age differences, the three communities look exactly the same, each exhibiting a telltale irregular weblike fabric, and a two-tier structure. "In form, function and metabolism, they are identical," Schopf said.