Extinctions of the past offer insight for future

It is an open question whether global warming has gone far enough so as to doom the existence of the majority of species on earth in some near future. But such a cataclysmic event has happened before. In fact, it has happened five times before. They are called the “5 Mass Extinctions.”

The oldest was 440 million years ago, when 86% of life was destroyed. The next was 365 million years ago, and 75% of life became extinct. The third was 250 million years ago and was the deadliest, with 95% of then-existing species dying off. The next was a mere 40 million years later, some 210 million years ago. The fifth, and probably best known, was 65 million years ago, the end of the Cretaceous Period and the end of dinosaurs, who had been living on this planet for 165 million years! And the end of 76% of the earth’s species.

But that’s where “we” come in. It was after this fifth mass extinction that the earth became habitable for mammals on land and sharks in the oceans. In short, it was what made the dinosaurs extinct that lead to the line of ancient beings that has evolved into humanity.

So far as is known, no species in existence today was present on earth before the first Mass Extinction. Each of us will have to make up our minds what that means about the past … and about the future.

Here is the one indisputable fact: If global warming does bring about an environment uninhabitable for human kind, it will be the first time in the long history of this planet that a species has created its own demise.

J.R. “DOC” IRWIN, PH.D. Bella Vista