Complex life emerged 1.5 billion years earlier than we thought

We’ve all learned that animals first began their Earthly journey around 635 million years ago. It’s a number well-ensconced in our collective scientific understanding. But new research suggests that the timeline of complex life may need a serious rethink.

A recent study led by an international team of scientists from Cardiff University points to a completely different story. They contend that complex life on Earth began a whopping 1.5 billion years earlier than what was previously believed.

This is not merely a correction of a few million years; it’s a massive leap into the past that fundamentally alters our understanding of life’s evolutionary timeline.

Discovering ancient complex life

The nerve center of this discovery is the Franceville Basin near Gabon, located on the Atlantic coast of Central Africa. It was here that the scientists found evidence of a prehistoric ecosystem housing the very first experiments in complex biological evolution.

Such findings were presented in the study, titled “Hydrothermal seawater eutrophication triggered local macrobiological experimentation in the 2100 Ma Paleoproterozoic Francevillian sub-basin.”

Dr. Ernest Chi Fru, the paper’s lead author at Cardiff University’s School of Earth and Environmental Sciences, played a vital role in this exploration. He explained that the discovery is based on the availability of phosphorus in the environment, a factor recognized as crucial for the evolution of life on Earth.

Finding the missing links

Until now, our understanding was that an increase in marine phosphorus and seawater oxygen concentrations was linked to an episode of biological evolution around 635 million years ago. However, Dr. Chi Fru’s findings bring a much earlier episode into focus, dating back 2.1 billion years.

“We already know that increases in marine phosphorus and seawater oxygen concentrations are linked to an episode of biological evolution around 635 million years ago. Our study adds another, much earlier episode into the record, 2.1 billion years ago,” Chi Fru stated.

The big picture

This discovery doesn’t just add another episode to the evolutionary timeline. It brings to light a series of processes that could have potentially triggered the evolution of large-sized fossils of macroorganisms much earlier than we anticipated.

These large-sized fossils, whose validity has been widely debated in the scientific community, are the earliest of their kind in the geologic record.

The Cardiff-led team’s geochemical analysis of the marine sedimentary rocks deposited 2.1 billion years ago offers new insights into this much-disputed collection of unusually large-sized fossils in the Francevillian basin.

Dr. Chi Fru further clarified that the underwater volcanoes, which appeared after the collision of the Congo and São Francisco cratons, might have created a nutrient-rich shallow marine inland sea.

This environment could have supported abundant cyanobacterial photosynthesis over an extended period of time, leading to the oxygenation of local seawater and the generation of a large food resource.

Evolution of complex life

According to the researchers, their study hints towards a two-step evolution of complex life on Earth. The first followed the initial rise in atmospheric oxygen content 2.1 billion years ago, and the second followed a second rise in atmospheric oxygen levels some 1.5 billion years later.

While the first attempt didn’t seem to take off on a global scale, the second attempt could be responsible for the animal biodiversity we see on Earth today.

The team is now focused on delving deeper into the environmental conditions that led to the emergence of these enigmatic fossils.

What does this mean for our understanding of life on Earth? Well, only time (and much more research) will tell. But for now, we can marvel at the fact that our planet was experimenting with complex life forms far earlier than we ever imagined!

This research has important implications, encouraging us to reconsider our understanding of complex life evolution. It suggests that the development of multicellularity might have occurred due to different environmental pressures than we thought.

It also questions the notion that complex life developed only once, encouraging more study of ancient ecosystems and their roles in Earth’s biodiversity. As this field grows, connecting ancient and modern life could reveal insights into the resilience and adaptability of life.

The study is published in the journal Precambrian Research.

Image Credit: Professor Abderrazzak El Albani of the University of Poitiers, France

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