CIVILIZATION
The Silurian Hypothesis
Could an Advanced Civilization Have Existed Before Us?
In 2018, scientists Adam Frank and Gavin Schmidt posed an intriguing question:
Could an industrial civilization have existed on Earth millions of years before humans appeared?
This idea, known as the Silurian Hypothesis, invites us to consider the possibility that ancient, advanced civilizations may have risen and fallen long before we arrived. Though no evidence directly supports this idea, the thought experiment sheds light on the limits of our ability to detect such civilizations and challenges our understanding of planetary history.
The Hypothesis in Context
The Silurian Hypothesis takes its name from a fictional alien race in the long-running British TV show Doctor Who. In the show, the Silurians were an advanced reptilian species who lived on Earth long before humans. Though Frank and Schmidt didn’t propose the existence of actual reptilian overlords, they used the name to explore the limits of our knowledge about Earth’s past.
Their central question is:
if an industrial civilization existed millions of years ago — say, during the time of the dinosaurs or earlier — would we be able to detect its traces today?
Given the forces of erosion, tectonic shifts, and the long passage of time, evidence of such a civilization might have been entirely erased.
Geological Time and the Preservation of Evidence
Earth’s history spans roughly 4.5 billion years, and modern humans have existed for just a fraction of that time. Civilization as we know it — complete with cities, agriculture, and industry — has only been around for a few thousand years. When we zoom out to the scale of millions or billions of years, it becomes clear that most evidence of human activity might not survive for very long on a geological timescale.
Fossils, for example, are relatively rare. Most living creatures don’t leave fossilized remains behind, and those that do are usually preserved in very specific conditions. Similarly, the remnants of human civilization — like buildings, roads, and even plastics — may not last long enough to be discovered by future archaeologists millions of years from now.
Frank and Schmidt point out that if an industrial civilization existed 60 million years ago, we might struggle to find any trace of it. Climate change, erosion, and the movement of tectonic plates could have erased most signs of its existence. This leads to an intriguing question: if we can’t find any evidence of such a civilization, how would we know it existed in the first place?
Searching for Industrial Byproducts
One way to detect an ancient civilization might be through the byproducts of industrial activity. Human civilization has left its mark on the Earth in the form of pollution. Plastics, synthetic chemicals, and even nuclear isotopes are distributed throughout the planet and may persist in the fossil record for millions of years. The Anthropocene, a proposed geological epoch that marks humanity’s impact on the Earth, could one day be recognized by layers of plastic and other industrial materials.
The Silurian Hypothesis suggests we look for similar markers in ancient geological layers. For instance, we might find unusual concentrations of carbon, isotopic signatures consistent with the burning of fossil fuels, or traces of synthetic chemicals that don’t occur naturally. However, detecting these markers would be difficult, especially if they’re buried deep within the Earth or have been diluted over time.
Why It Matters
While the Silurian Hypothesis may sound like science fiction, it serves as a valuable scientific thought experiment. Frank and Schmidt’s hypothesis encourages us to think about the longevity of civilizations and the broader impact of industrial activity on a planet. It raises important questions about sustainability and what traces our own civilization might leave behind.
If we can’t find evidence of an ancient civilization, does that mean they never existed, or have the signs simply eroded over time? And what will remain of human civilization millions of years from now? By exploring these questions, we gain a deeper appreciation of the fragility of our world and the importance of preserving it for future generations.
Conclusion
The Silurian Hypothesis doesn’t claim that an ancient advanced civilization did exist — it simply asks whether we’d be able to detect it if one did. It challenges us to think about the impermanence of our civilization and the legacy we might leave on Earth’s geological history. Whether or not an ancient industrial society once thrived on Earth, the hypothesis prompts us to reflect on our own future and the marks we are leaving behind for distant generations — or even species — to discover.
