Humanity is 'cutting down the tree of life', warn scientists

James Marshall
October 19, 2018

Prof Douglas Futuyma at Stony Brook University in the United States, who was not part of the research team, said: "They have made a dramatic and convincing statement of how much evolutionary diversity has already been lost".

They expect that in the next 50 years, our planet's evolutionary diversity will be so destroyed that it will take it millions of years to recover.

A new study has shown that many species of mammals will disappear in the next 50 years due to human activities. It will take more than 5 million years to regenerate the biodiversity that was lost from giant Ice Age species.

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. The International Union for the Conservation of Nature estimates that 99% of critically endangered species and 67% of endangered species will die out within the next 100 years. They believe that people are responsible for eliminating the evolutionary diversity that is on the planet. Succeeding each mass extinction evolution has developed anew to diffuse the gap created.

In the new study, researchers from Aarhus University and the University of Gothenburg used an extensive database of mammals both in existence today and those that have gone extinct since the rise of Homo sapiens to assess the future of mammalian biodiversity. Through computers and on-hand data on mammal species relationships and sizes, they developed simulations to calculate how much time evolution needs to work its magic. 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.

One of the problems that the scientists highlighted in their report is that some of the mammals with the fewest number of species are going extinct or are the most vulnerable. Matt Davis, a paleontologist at Aarhus University who led the study, cited the shrew as an example.

The elimination of some species meant the entire disappearance of their evolutionary branches; others lived on through their close relatives.

Over the past 130,000 years since the Late Pleistocene, we've already lost more than 2.5 billion years of evolutionary history. That's not the case for some megafauna species such as giant sloths and sabre-toothed tigers, which used to be highly evolutionary distinct and went extinct 10,000 years ago, with humans playing a major role. Some extinct animals with few close relatives, like the Australian leopard-like marsupial lion or the unusual South American Macrauchenia (imagine a lama with an elephant trunk) were evolutionary distinct lineages. It adds to a growing body of recent research that has warned of imminent mass extinction driven by unsustainable human activity, the climate crisis, and inadequate conservation efforts.

Asian elephants, one of only two surviving species of a once mighty mammalian order that included mammoths and mastodons, have less than a 33 per cent chance of surviving past this century.

"We now live in a world that is becoming increasingly impoverished of large wild mammalian species", Aarhus University Professor Jens-Christian Svenning said in a statement.

'The few remaining giants, such as rhinos and elephants, are in danger of being wiped out very rapidly'.

Fortunately, the study's findings and data are useful in identifying endangered and evolutionary distinct species, which will help us determine the more critical extinctions we should concentrate on preventing.

Other reports by Click Lancashire

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