Mass extinctions reviewed

This article is written by two members of Cambridge University’s Centre for the Study of Existential Risk. It outlines the complex interaction between earth systems that led to the mass extinctions in the Permian and late Cretaceous geological periods 250 and 66 million years age and raises the possibility that the earth is now entering a sixth great extinction arising this time from human activity.

Humanity lives far more precariously than we think, dependent upon a great many global systems, from the environment that provides us with food, water, clean air and energy to the global economy that supplies goods and services where we want them and when we want them, often on a “just in time” basis.

From looking at the historical, and the geological, record it becomes clear that such systems can easily pass through phase changes in which a previously stable system quickly, and sometimes irrevocably, changes into a chaotic one. Scientists have already identified how this might occur in relation to phenomena such as climatic tipping points (where climate change becomes self-sustaining, rather than being simply “man-made”), ecosystem collapse (where the loss of a few key species can cause whole ecosystems to disappear), and hyperinflation (where previously stable economic institutions cease functioning and money loses its value).

Nor may the systems we ourselves have designed be any less fragile in this respect. Indeed, many of our institutions have shown themselves to be almost entirely unconcerned with human well-being; so long as they can serve the interests of short-term profit maximisation, voter turnout and other, ultimately useless, goals.

Yet, it might not be all bad news for humanity. Some theorists suggest that the catastrophic effects of a mass extinction tend to sweep away the highly adapted specialists of the era, and allow more flexible generalists to survive and eventually flourish into new forms. So perhaps we can take comfort from the fact that humans have showed themselves to be the ultimate generalists, adapting to survive, though not always thrive, in every habitat on Earth, and even in outer space.

But we should also reflect on the fact that most of this flexibility flows not from our biology but from the technologies we have created. Not only are these the very technologies that are leading us to push global systems as far as we have, but they are rapidly passing out of the realms of human comprehension in their complexity and sophistication. Indeed, it now requires immense individual knowledge to use and maintain them, making each of us, individually, just the sort of adapted specialists most vulnerable in a mass extinction event – something that may not be quite such good news after all.