HUMANS will cause so many mammal species to go extinct in the next 50 years that the planet’s evolutionary diversity won’t recover for three to five million years, a team of researchers has found.
The study, published in Science Daily, found humans have helped propel the extinction of more than 300 mammal species — equalling a staggering loss of 2.5 billion years’ worth of unique evolutionary history.
Mammals have been on the planet for roughly 200 million years. Following the demise of the dinosaurs, mammals flourished, evolving into a mindboggling variety, from the tiny Etruscan shrew to the largest animal ever – the blue whale. After all of those millennia of evolution, it took barely 100,000 years for one relatively young member of the group – humans – to bring everything crashing down.
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And we have done such a convincing job, scientists are labelling this the sixth mass extinction.
There have been five upheavals over the past 450 million years when the environment has changed so dramatically that the majority of Earth’s plant and animal species became extinct. After each mass extinction, evolution has slowly filled in the gaps with new species.
This time, however, is different.
The team of researchers behind the report from Aarhus University and the University of Gothenburg calculated that the extinctions are moving too rapidly for evolution to keep up.
Sadly, the team’s estimation of a three to five million year recovery time is a best-case scenario. And that would only return the planet to current biodiversity levels.
Another study published in the Proceedings of the National Academy of Sciences, predicts it will take at least another two million years to be restored to the level it was before the arrival of modern humans – that’s five to seven million in total. And that is only if people cease all poaching, pollution and habitat destruction in the next 50 years.
But even in that best-case scenario, the timeline depends on how quickly mammals start recovering. If the extinction rate doesn’t start falling for another 20-100 years, more species will likely disappear, causing greater diversity loss, the study said.
It’s a “pretty scary” situation we’ve created, paleontologist Matt Davis of Denmark’s Aarhus University, told The Guardian. “We are starting to cut down the whole tree [of life], including the branch [humans] are sitting on right now.”