Wednesday, 19 October 2016

The Zoologist Who Cried Climate Change

Why did the mammoth go extinct? Why are there no longer lions in Europe? Why is the largest predator in Australia a smallish dog? There is a clear and concise explanation for every last one of these extinctions, backed up by a great deal of evidence: In North America, the mammoths and lions disappeared within centuries of humans first arriving, in Europe they lasted until warming temperatures improved conditions for people, and on their last island refugees, such as Wrangel island off the coast of Siberia, they lasted until just 4000 years ago, when finally, people arrived there too. A similar story is seen in Australia. When humans first arrived 50,000 years ago, the native megafauna of the continent immediately collapsed, leaving only a few medium sized marsupials, such as the thylacine, as the biggest predators on the continent. Later, a new wave of people arrived, this time bringing more advanced weapons and, crucially, dogs, resulting in the extinction of all thylacine populations save the one on Tasmania, where dingos the never reached.

The evidence for this scenario is clear and conclusive, backed up by multiple studies and seen across the world. The unique birds of New Zealand were doing just fine until 800 years ago, when the first Maori arrived and promptly proceeded to wipe nearly all of the flightless and many of the flighted species out. When the Europeans arrived several centuries later, they merely finished the job. The megafauna of South America, once the most biodiverse in the world, died out within centuries of humans arriving, after having endured millions of years of ecological and climatic upheavals with little to no effect. The giant lemurs and fossas of Madagascar were eradicated shortly after the arrival of the first humans 3000 years ago, and the few and tiny populations of elephant birds that had managed to cling on disappeared once again after the coming of the Europeans. Arguably most famous of all recent extinctions is that of the dodo, though what fewer people know is that the dodo shared its island home of Mauritius with a wide variety of odd and endemic species, including giant turtles and multiple other species of flightless birds, all of which were wiped out shortly after people came.

This does not seem like a complicated issue - quite the opposite in fact. Every time humans arrive on a new landmass, the result has been an immediate wave of extinctions. This is seen across the whole world, and evidence for it is ample. Surely, nobody would be naive or stubborn enough to contest this, right? As we will soon see, the bounds of human incredulity and denial are truly limitless.

Raphus cucullatus, the famous dodo. Once abundant across its habitat, it is now, as the saying goes, "dead as a dodo"