Deep in the heart of Africa, buried beneath layers of primordial rock, lie the remains of creatures that shouldn't exist, and that challenge everything we thought we knew about the evolution of life on Earth. These ancient pioneers of evolution could rewrite (for the umpteenth time) the natural history books.
A dive into the distant past
Be careful, we're not talking about a few million years ago, when dinosaurs dominated the planet. We're going much, much further back in time: 2,1 billion years ago, when Earth was a decidedly different place. The atmosphere was devoid of oxygen, the oceans were a primordial chemical soup, and life, well, was thought to be limited to simple single-celled bacteria.
But in training Franceville in Gabon, scientists from Cardiff University found something extraordinary: fossils of complex multicellular organisms, up to 17 centimeters large. To put it bluntly, it's like finding a smartphone in an Egyptian tomb. It makes no sense, yet it's there.
The debate rages on
Dr. Ernest Chi Fru, lead author of the study, has clear ideas. There, he says, a localized environment was created where cyanobacterial photosynthesis was abundant for a prolonged period of time. And this led to the oxygenation of local marine waters and the generation of a large food resource.
Naturally, such a discovery does not go unnoticed. The scientific community is divided. Some see evidence of early primordial evolution in these fossils, others are more skeptical. “They could be inorganic structures,” they say. “Concretions, pyrites, geological illusions”.
The stakes are high: if confirmed, these fossils would anticipate the evolution of complex life by as much as 1,5 billion years.
A primordial oasis in the desert of time
How could complex life emerge so early? Researchers have a fascinating theory. Imagine two giant pieces of Earth's crust colliding, creating a shallow inland sea. Underwater volcanic eruptions enrich these waters with oxygen and phosphorus. Voila, you have created a primordial oasis in an otherwise hostile world.
This unique environment would have provided ideal conditions for an explosion of complex life, an evolutionary experiment ahead of its time. But as with any experiment, there is always the risk of failure.
Life always finds a way… or does it?
The most surprising thing about this story is not only that complex life could have emerged so early, but that it then disappeared. For almost 1,5 billion years, the Earth has once again been the domain of single-celled organisms. It's as if nature made an early attempt, failed, and then waited an eternity before trying again.
I am not against the idea that there were higher nutrients 2,1 billion years ago, but I am not convinced that this could have led to diversification to form complex life
Graham Shields ofUniversity College London
Cosmic implications
However, if this discovery is confirmed the implications would go far beyond Earth. Think of all those “potentially habitable” planets we are discovering in the universe. If complex life can emerge under such primordial conditions, perhaps the universe is more alive than we think.
On the other hand, if these primordial life forms became extinct so quickly, perhaps the road to complex and long-lasting life is more difficult than we imagine. That's a sobering thought, right?
The debate continues
Science, in its essence, is an ongoing dialogue. This discovery, published in the journal Precambrian Research (I link it to you here), is just the latest chapter in a conversation that has lasted for centuries. It will take years, perhaps decades, before a consensus is reached on these mysterious fossils from Gabon.
Meanwhile, these ancient remains remind us how little we still know about our planet's early history. Earth has 4,5 billion years of secrets to unlock, and we've only just begun to scratch the surface.
