SOURCE: The Guardian

DATE: October 15, 2018

SNIP: Humanity’s ongoing annihilation of wildlife is cutting down the tree of life, including the branch we are sitting on, according to a stark new analysis.

More than 300 different mammal species have been eradicated by human activities. The new research calculates the total unique evolutionary history that has been lost as a result at a startling 2.5bn years.

Furthermore, even if the destruction of wild areas, poaching and pollution were ended within 50 years and extinction rates fell back to natural levels, it would still take 5-7 million years for the natural world to recover.

Many scientists think a sixth mass extinction of life on Earth has begun, propelled by human destruction of wildlife, and 83% of wild mammals have already gone. The new work puts this in the context of the evolution and extinction of species that occurred for billions of years before modern humans arrived.

“We are doing something that will last millions of years beyond us,” said Matt Davis at Aarhus University in Denmark, who led the new research. “It shows the severity of what we are in right now. We’re entering what could be an extinction on the scale of what killed the dinosaurs.

That is pretty scary. We are starting to cut down the whole tree [of life], including the branch we are sitting on right now.

There are still many mammal species left, but all of these would have to evolve for 5-7m years into the future to get back to the level of diversity present before modern humans arrived, the researchers estimated.

Prof Douglas Futuyma at Stony Brook University in the US, 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. The most important point is one that I believe is already widely recognised: humans are extinguishing not only many species, but many kinds of species.” He said that while overall evolutionary distinctiveness can be recovered over time, particular species – such as elephants – would never re-evolve if lost.