Evidence has been found in marine sedimentary rocks near Gabon in central Africa.
An international team of researchers has challenged the long-held belief that complex life forms first appeared on Earth 635 million years ago, presenting findings that show life may have existed more than a billion years ago.
In a study published in Precambrian research Scientists from Cardiff University in Wales on Monday found ecological evidence suggesting that complex life existed 1.5 billion years earlier than previously thought, but failed to “spread” globally.
The study authors say this evidence may point to a “two-step” evolution of complex life on Earth.
The evidence was found in marine sedimentary rocks from the Franceville Basin near Gabon in central Africa, which witnessed an episode of underwater volcanic activity from two Precambrian continents, or cratons, that collided 2.1 billion years ago, according to the study.
“The availability of phosphorus in the environment is thought to be essential for the evolution of life on Earth, particularly in the transition from simple single-celled organisms to complex organisms such as animals and plants,” said Dr. Ernest Che Fro, lead author of the study from the School of Earth and Environmental Sciences at Cardiff University, in an article published by the American website “Science Alert.” press release Monday.
The two Precambrian regions examined in the study are the Congo and São Francisco regions, two stable Archean landmasses that were once part of a single landmass in central Africa and eastern Brazil, according to Frew.
“We believe that underwater volcanism, which followed the collision and fusion of the Congo and Sao Francisco cratons into one main body, restricted and even cut off this body of water from the global ocean to create a shallow, nutrient-rich inland sea,” Frow said in a press release.
The researchers believe that the underwater volcanic environment paved the way for “cyanobacterial photosynthesis,” which created “a generation of large food resources” to enable the formation of complex life.
Fossils of large organisms from this period have been the subject of debate in the scientific community, according to Frew, who believes the study’s findings may answer questions surrounding the fossils’ origins.
“This would have provided enough energy to fuel the increased body size and more complex behavior seen in simple, animal-like primitive life forms such as those in fossils from this period,” Frow said.
But complex life forms did not spread globally from the “restricted nature” of the underwater region, and eventually became extinct, according to the study.
“While the first attempt failed to spread, the second attempt succeeded in creating the animal biodiversity we see on Earth today,” Frow said.