Theory claims complex life on Earth may be much older than previously thought – BBC News

Image source, Abderrazzak El Albani

Legend, A team of scientists claims to have found evidence of nutrients that they believe created these formations in Gabon

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Author, Georgina Rannard

Role, Science journalist

3 hours ago

A group of scientists say they have found new evidence to support their theory that complex life on Earth may have begun 1.5 billion years earlier than previously thought.

The team, working in Gabon, says it has discovered evidence deep in the rocks showing environmental conditions suitable for animal life 2.1 billion years ago.

But they say these organisms were limited to one inland sea, did not spread globally and eventually became extinct.

These ideas depart considerably from conventional thinking, and not all scientists agree.

Most experts estimate that animal life began about 635 million years ago.

This research adds to the ongoing debate over whether the previously unexplained formations discovered in Franceville, Gabon, are actually fossils or not.

Scientists examined the rock around the formations to see if it showed evidence of nutrients like oxygen and phosphorus that could have supported life.

Professor Ernest Chi Fru of Cardiff University worked with an international team of scientists.

He told BBC News that if his theory was correct, these life forms would have been similar to slime moulds – a single-celled organism without a brain that reproduces with spores.

But Professor Graham Shields of University College London, who was not involved in the research, says he has some reservations.

“I’m not against the idea that there were more nutrients 2.1 billion years ago, but I’m not convinced that it could lead to diversification to form complex life,” he said, suggesting that more evidence was needed.

Professor Chi Fru said his work had helped prove ideas about the processes that create life on Earth.

“We say, look, there are fossils here, there is oxygen, this stimulated the emergence of the first complex living organisms,” he said.

“We’re seeing the same process as in the Cambrian period, 635 million years ago, which helps us confirm it. It helps us understand where we all come from,” he added.

Image source, Abderrazzak El Albani

Legend, Artist’s impression of what life might have looked like 2.1 billion years ago

The first hint that complex life might have appeared earlier than previously thought came about 10 years ago with the discovery of what is called the Francevillian formation.

Professor Chi Fru and his colleagues said the formation consisted of fossils that indicated evidence of life capable of “wriggling” and moving on its own.

The results were not accepted by all scientists.

To find more evidence to support their theories, Professor Chi Fru and his team have now analysed sediment cores extracted from rock in Gabon.

The chemistry of the rock showed that a “laboratory” of life had been created just before the formation appeared.

They believe the high levels of oxygen and phosphorus were created by the collision of two continental plates underwater, creating volcanic activity.

The collision cut off some of the ocean water, creating a “shallow, nutrient-rich marine inland sea.”

Professor Chi Fru explains that this protected environment provided the conditions for photosynthesis, leading to significant amounts of oxygen in the water.

“This would have provided enough energy to support the increased body size and more complex behavior seen in primitive, simple animal life forms such as those found in fossils from this period,” he said.

But he says the isolated environment also led to the extinction of life forms because there were not enough new nutrients brought in to maintain the food supply.

Elias Rugen, a doctoral student at the Natural History Museum who was not involved in the research, agreed with some of the findings, saying it was clear that “the oceanic cycles of carbon, nitrogen, iron and phosphorus were all doing something a little bit unprecedented at this point in Earth’s history.”

“There is nothing to say that complex biological life could not have emerged and flourished as early as 2 billion years ago,” he said, but added that more evidence was needed to support these theories.