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Post by benjamindavis on Sept 21, 2023 2:59:36 GMT
How will humans as a species go extinct?
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lilith
Bronze Member
Posts: 32
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Post by lilith on Sept 26, 2023 21:49:13 GMT
The species Homo sapiens evolved some 300,000 years ago and has come to dominate Earth, unlike any species that came before. But how long can humans last? Eventually, humans will go extinct. At the most wildly optimistic estimate, our species will last perhaps another billion years but end when the expanding envelope of the sun swells outward and heats the planet to a Venus-like state. But a billion years is a long time. One billion years ago life on Earth consisted of microbes. Multicellular life didn’t make its debut until about 600 million years ago when sponges proliferated. What life will look like in another billion years is anyone’s guess, though one modeling study published in 2021 in Nature Geoscience suggests that Earth’s atmosphere will contain very little oxygen by then, making it likely that anaerobic microbes, rather than humans, will be the last living Earthlings.
If surviving to see the sun fry Earth is a long shot, when is humanity likely to meet its doom? Paleontologically, mammalian species usually persist for about a million years, says Henry Gee, a paleontologist and senior editor at the journal Nature, who is working on a book on the extinction of humans. That would put the human species in its youth. But Gee doesn’t think these rules necessarily apply to H. sapiens. “Humans are rather an exceptional species,” he says. “We could last for millions of years, or we could all drop down next week.” Opportunities for doomsday abound. Humans could be wiped out by a catastrophic asteroid strike, commit self-destruction with worldwide nuclear war, or succumb to the ravages caused by the climate emergency. But humans are a hardy bunch, so the most likely scenario involves a combination of catastrophes that could wipe us out completely.
Some species killers are out of our control. In a 2021 paper in the journal Icarus, for example, researchers describe how asteroids comparable to the one spanning 10 to 15 kilometers in diameter that killed off the nonavian dinosaurs hit Earth approximately every 250 million to 500 million years. In a preprint paper posted on the server arXiv.org, physicists Philip Lubin and Alexander Cohen calculate that humanity would have the ability to save itself from a dino-killer-sized asteroid, given six months’ warning and an arsenal of nuclear penetrators to blow the space rock into a cloud of harmless pebbles. With less warning or a larger asteroid, Lubin and Cohen suggest that humanity should give up and “party” or “move to Mars or the Moon to party.”
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