Tuesday, July 20, 2021

Talking about humans

Humans occupy a minuscule amount of time relative to the age of the Earth. The best available evidence places the first modern humans around 200,000 years ago. Relative to the Earth, which is about 4.5 billion years old, our species has occupied only 0.0044% of the Earth’s history. For over 99% of the Earth’s history, there were no humans. Now consider the fact that humans have really only possessed what we can call “advanced” technology for about one hundred to two hundred years. For the vast majority of our own existence, we were simply hunters and gatherers. 

Given this information, what will our species leave behind that could one day be found as evidence for our existence? Will we leave anything behind that would suggest a technologically advanced civilization once occupied a sliver of time in Earth’s history? Even our oldest structures, such as the Great Pyramid, will erode away and turn to dust, leaving no evidence of their existence. Human fossils would perhaps hint at some form of intelligence, yet it wouldn’t offer any insight into our civilization. All of our cities will one day disappear and return to the Earth, leaving no trace of their existence. Interestingly, one of the only forms of evidence that our civilization once existed will be in the form of plastic. Given how plastic is extremely difficult for natural processes to break down, humans will likely leave a marker in the geologic record, a layer of plastic. Yet even this layer of plastic would be extraordinarily thin, especially given that we haven’t even been using plastic for a hundred years. Given its widespread use and abundance, however, humans will leave behind a marker in the Earth’s rocks. And plastic isn’t the only marker. Nuclear tests that occurred over the course of the Cold War have left radioactive markers in the rocks, and our greenhouse gas emissions will also likely leave a mark in the rocks. If we one day go extinct, and another civilization evolves in the far future, perhaps they will identify a pattern. 

As soon as this particular species evolves and becomes widespread around the globe, the Earth underwent radical changes. Plastic appears in the rocks, radioactive material becomes widespread, there is a sudden increase in the amount of greenhouse gases, and wherever this species travels, other species quickly vanish. The legacy of the human species, one that will become ingrained in the very geology of our world, will a tell a story of a species who took their world for granted. 

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