Guns and Climate and Mammoths, Oh My!
The BBC has a piece recapping arguments over whether humans are responsible for the megafauna extinction at the end of the Pleistocene. There really isn’t anything fresh there, though it does name advocates on both sides.
Frankly, that this dispute continues puzzles GG, but perhaps the issue is more in the word “cause”. Are we talking proximate cause or ultimate cause? Are we identifying the particular events that pushed a species over the edge, or a unique link in a chain of events?
Consider an analogy: when a person is murdered by gunshot, you can say that the gun was the proximate cause. If there were no guns, some argue, there would be no murders. But a pile of guns in a room doesn’t result in deaths; the unique element in there is somebody willing to pull a trigger. Probably some of those people would not use a knife or baseball bat or poison, but probably some would; removing guns might reduce the death toll but not end murder altogether.
OK, how does this compare with the Pleistocene megafauna extinction? It is possible that the proximate cause of extinction for some species was a change in climate, or perhaps climate was only just removed because of its change impacting food sources. And in those instances you might argue that if there was no climate change, that species might be here today. Does that finger the changing climate as the ultimate cause?
GG’s view is that the scientific dispute actually is quite misleading. If humans do not invade a continent, there is no massive extinction event; the presence of humans is the ultimate cause of the megafauna extinction, the unique link in the causal chain that, if removed, breaks the whole chain. GG gets the distinct impression that the scientific argument is over proximate causes–what was the murder weapon? Spears? Fire? Competition for food? Disease? Warming climate? While there is a great deal of value to be learned about just exactly how these animals left the face of the earth (which is why these scientists argue), this should not be confused with the basic bottom-line truth: human involvement is the unique element, the ultimate cause. No humans, no massive extinction event.
We, all of us, have forebears who contributed to the extinction of these large Pleistocene animals. Pretending that the last deglaciation was so different from the dozens that preceded that it was the sole cause of extinction is an act of delusion. We should, as a species, accept our culpability even though those ancestors were not intending (so far as we know) to wipe out these species. And we should therefore accept a special responsibility to not let it happen again, deliberately or inadvertently. Let us accept our history, learn from it, and be the better for it.