Could Earth Have Once Harbored a Pre-Human Industrial Civilization?
Complex life on our planet has existed for at least 400 million years, while life itself has been around for over 3.5 billion years. However, as a species, we have only attempted to create an industrial civilization around 300 years ago.
This leaves over 3 billion years of pre-human history unaccounted for—a duration too long for the rise and fall of not just one, but potentially several industrial civilizations that may have existed!
Life has existed on this planet for over 3.5 billion years. (Photo: WALTER MYERS / STOCKTREK IMAGES / GETTY IMAGES).
What if an earlier industrial civilization (pre-human) existed on Earth millions of years ago? If so, how could we prove—or disprove—it?
This is the crux of the Silurian Hypothesis, an intriguing thought experiment that emerged from a study published in 2018 in the International Journal of Biology.
In the British science fiction television series produced by the BBC titled “Doctor Who”, a species of extraterrestrial beings known as Silurians exist—these are humanoid reptiles with advanced technology that lived long before humans.
The possibility of life existing elsewhere in the universe and its parallels with the Anthropocene epoch—the current geological age, where humans have impacted Earth to an irreversible extent—has long compelled Adam Frank, a professor of astrophysics at the University of Rochester, New York, USA (one of the study’s co-authors), to delve deeper into research.
“Could any civilization reaching our level of energy consumption trigger its own version of climate change?—I wondered. If there are extraterrestrial civilizations, would they also cause climate change?” Professor Adam Frank pondered these questions deeply.
With this train of thought, Professor Adam Frank visited NASA’s Goddard Institute for Space Studies (GISS), a premier climate science facility at Columbia University, New York, and shared his thoughts with climate researchers.
“I met with Professor Gavin A. Schmidt (a climatologist and director of GISS), and began discussing geological history millions of years ago,” Professor Adam Frank excitedly recounted.
Searching the Geological Records of Earth
Homo sapiens (modern humans) first appeared on Earth about 300,000 years ago.
The question of whether there was a pre-human civilization prompted the two professors to seek evidence from approximately 4 million to 400 million years ago. Did they succeed?
Going back hundreds of millions of years to find traces of a potential pre-Homo sapiens civilization is not an easy task.
Earth’s history through various periods. (Source: U.S. GEOLOGICAL SURVEY).
“After millions of years, Earth has been significantly reshaped. You wouldn’t find any statues, buildings, or anything left. Fossil records are virtually non-existent because everything would have turned to dust. The only evidence would come in the form of chemical traces,” Professor Adam Frank explained.
“You would have to examine each layer of rock and then try to discern patterns—looking for changes in things like carbon or oxygen isotopes. An industrial civilization would emit a lot of carbon dioxide into the atmosphere. Microplastics or nanomaterials would also serve as good indicators that an industrial civilization existed in ancient times—that’s all we need to find out,” he added.
Professors Schmidt and Frank were particularly drawn to a geological period known as the Paleocene-Eocene Thermal Maximum (PETM), because something unusual occurred on our planet 56 million years ago: The average temperature of Earth surged by about 9.4 degrees Celsius compared to what we have today, and the world became a warm and lush place.
They investigated the ratios of carbon and oxygen isotopes from the PETM and indeed observed a spike, but they also noted a temperature decline, all occurring over hundreds of thousands of years, not at the pace at which carbon is currently choking the atmosphere.
Professor Frank stated that the chemical differences of the PETM indicated a long-term climate change.
They also examined other “sudden events” throughout the time that are visible in the geological record, including ocean anoxic events—when oceans became depleted of oxygen—and extinction events.
Not surprisingly, these too were not signs of an industrial civilization.
Applying the Philosophical Theory of Occam’s Razor
In 1324, English theologian William of Ockham proposed a famous philosophical theory known as “Occam’s Razor”, suggesting that if a scientific problem can be explained with the fewest hypotheses, it is the most accurate.
“The hypothesis that Earth may have nurtured long-extinct industrial civilizations and that their existence may be recorded in the geological record related to signs of climate change is very intriguing; however, even the authors find it hard to consider it a truth,” Stephen Holler, an associate professor of physics at Fordham University in New York City, told Popular Mechanics.
In the 14th century, Franciscan philosopher and theologian William of Ockham suggested that the most feasible solution to a problem is the simplest one.
Associate Professor Stephen Holler remarked, “This is very likely the case here. We can explain much of the geological record of natural phenomena, so it is not necessary to invoke lost civilizations.”
However, if a prior industrial civilization did exist and its extinction was a result of catastrophic climate change due to industrial activities, we should heed the warnings because, as a civilization, we are standing on the brink.
The Silurian Hypothesis states: “The more sustainable a society is in its energy production and resource extraction—arguably, the more advanced a society is—the smaller the trace it leaves on the planet.”
If you’re not clear about what you’re looking for, you might not see it. (Illustration: Internet).
However, these traces would likely translate into some key points in the geological record during that period. For instance, the more plastic or persistent synthetic molecules we produce, the higher the chances future civilizations will find traces of us.
(Our society produces 300 million tons of plastic each year globally—almost equivalent to the weight of the entire population!).
Or, even if we were to wipe the Earth clean with a nuclear disaster, radioactive particles would persist in the soil for decades/centuries thereafter, signaling that we once existed.
Professor Adam Frank stated: “With the Silurian Hypothesis, we have outlined the types of signals our civilization would leave behind if we were to vanish, and someone were to search for our civilization in 10 or 20 million years.”
But above all, the experiment conducted by the two professors has highlighted certain deficiencies in our current scientific apparatus.
Professor Frank explained: “In the case of a prior species’ industrial activity being particularly brief, we would not be able to detect it in ancient sediment layers with the tools and methods we currently possess. If you want to search for evidence of a past civilization, you need to carry out unprecedented studies and develop new methods.”
Remember, we’re talking about the evolutionary process of complex life over millions of years.
And although both Professors Frank and Schmidt do not truly believe that an industrial civilization existed prior to us, the main takeaway of the Silurian Hypothesis, Professor Frank said, is that if you’re not clear about what you’re looking for, you might not see it.
According to the Silurian Hypothesis, not pyramids, not skyscrapers, not Styrofoam, not Shakespeare—ultimately, we will only be known by a change in the rocks, marking the beginning of the Anthropocene Epoch!
