(2022-08-02) Could An Industrial Prehuman Civilization Have Existed On Earth Before Ours

Could an Industrial Prehuman Civilization Have Existed on Earth before Ours? One of the creepier conclusions drawn by scientists studying the Anthropocene—the proposed epoch of Earth’s geologic history in which humankind’s activities dominate the globe—is how closely today’s industrially induced climate change resembles conditions seen in past periods of rapid temperature rise.

“These ‘hyperthermals,’ the thermal-maximum events of prehistory, are the genesis of this research,” says Gavin Schmidt, climate modeler and director of the NASA Goddard Institute for Space Studies. “Whether the warming was caused by humans or by natural forces, the fingerprints—the chemical signals and tracers that give evidence of what happened then—look very similar.”

The canonical example of a hyperthermal is the Paleocene-Eocene Thermal Maximum (PETM), a 200,000-year period that occurred some 55.5 million years ago when global average temperatures rose by five to eight degrees Celsius (nine to 14 degrees Fahrenheit). Schmidt has pondered the PETM for his entire career, and it was on his mind one day in 2017 when University of Rochester astrophysicist Adam Frank paid him a visit.

“To estimate the odds of finding artifacts,” Schmidt says, “the back-of-the-envelope calculation for dinosaur fossils says that one fossil emerges every 10,000 years.” Dinosaur footprints are rarer still.

Consider our own industrial age, which has existed for only about 300 years out of a multimillion-year history of humanity. Now compare that minuscule slice of time with the half a billion years or so that creatures have lived on land. Humanity’s present rapacious phase of fossil-fuel use and environmental degradation, Frank says, is unsustainable for long periods. In time, it will diminish either by human choice or by the force of nature, making the Anthropocene less of an enduring era and more of a blip in the geologic record. “Maybe [civilizations like ours] have happened multiple times, but if they each only last 300 years, no one would ever see them,” Frank says.

“Of course, no matter what, this is going to be interpreted as ‘Astronomers Say Silurians Might Have Existed,’ even though the premise of this work is that there is no such evidence,” he says. “Then again, absence of evidence is not evidence of absence.” (Silurian Hypothesis)