Many Species of Ancient, Massive Mammals Went Extinct Thanks to Early Humans

Thursday, 19 April 2018 - 6:41PM
Thursday, 19 April 2018 - 6:41PM
Many Species of Ancient, Massive Mammals Went Extinct Thanks to Early Humans
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Turns out, the whole "humans killing off endangered animals" phenomenon is hardly a recent one, and we took out some big ones in our early days.

The Americas alone used to be full of huge mammals during the Pleistocene era, otherwise known as the Ice Age. Among them were wooly mammoths that could be up to 11 feet (3.4 meters) high, the short faced-bear which could stand 10 feet (3 meters) tall on its back feet, and - of all things to be giant - the South American giant ground sloth which measured at 20 feet (6 meters) long and were the same size as a modern elephant. 

New research from a team led by paleo-botanist Felisa Smith at the University of New Mexico determined that up to 125,000 years ago, humans were already impacting the average size of mammals, with the disappearance of the largest mammal species being caused by humans instead of a naturally occurring trend.

Nearly all of these extinctions of megafauna (the official name for really big animals) happened after the arrival of early humans all over the globe during the Pleistocene era. Smith looked at fossils dating as far back as 65 million years ago, when dinosaurs were dying out and mammals became the biggest creatures on the planet, and found that over those millions and millions of years, being large didn't hinder their chances of survival.

But that changed sharply at just around the time when we know humans were migrating out from Africa to other continents. 

Overhunting was unsurprisingly one of the major reasons, as giant animals made for easy targets among early human hunters. But it wasn't the only way humans impacted megafauna, as our habits of burning grasslands they used and competing with other carnivores also messed with the ecosystem. By crossing into these new lands, we were acting as an invasive species, after all.

Of course, due to more recent human-caused phenomenons like climate change, we're still continuing to threaten modern megafauna like elephants, whales, rhinos, and giraffes (which just recently found their way onto the endangered species list). According to Smith, it's important to research how we're doing this, because the ecosystem always changes when its biggest players go missing.

Smith said the following in an official statement from UNM:

Opening quote
"Megafauna play a really important role in ecosystems which we are just beginning to appreciate. For example, as they walk their massive size compacts the soil, which can lead to changes in gas exchange or water tables. They change the structure of vegetation through their browsing and help maintain open grasslands. They burp methane, a greenhouse gas and even influence the distribution of nitrogen and phospherous on the landscape. We are not entirely sure what the potential loss of these 'ecosystem engineers' could lead to. I hope we never find out."
Closing quote

In large and small ways, the Earth's ecosystem would be very different if extinct megafauna were still around. It's impossible to tell how we'd handle it; no matter how big they get, dying via sloth attack is a terrible, adorable way to go. 

Science News