Richard Zurawski

In the course of my Friday Science Files with Andrew Krystal I often touch upon the risks that we as a species are faced with, the things that threaten our survival. It is a fact that 99.9 per cent of all the species that have ever existed in the past roughly four-billion years of life on the Earth are now extinct, gone forever more. That means that only one in a thousand species that has ever lived is alive today. In its crudest, most simplistic expression it means that the half life, the average life span that we can expect of a species is in the order of four million years.

Some species live longer, some shorter, but the equation is the same for all plants, animals, fungi and microbes, we live to die as individuals and as species. What seems to be certain is that the tapestry of life continues, with constant ebbing and flowing of species.

Probably the most successful of all creatures were the anaerobes that held the dominant sway over the earth for almost three billion years. In the end most of the archaic anaerobes fell victim to their our successes and three billion years passed and new better adapted more complex life succeeded them. If we take the anaerobes and and their time out of the lifeline and just deal with the past half-billion years, we hone the average lifetime of a species considerably. The average lifetime of a species falls to roughly half-a-million years.

Why do I mention this? Homo Sapiens Sapiens, (read: you and I) have graced Terra Firma, as a species, for something like between 200 and 300,000 years. That is preciously close to the average life span of a species on this planet.

Now, that average of half-a-million years is for species that do not nudge, push and mangle their environment, but rather live within its confines. It seems that as long as the ecosystem remains stable the odds of a species surviving goes up. As soon as changes happen to the ecosystem, extinction rates climb. Look around you. Everything seems to be changing as far as the weather and the climate and the make up of the atmosphere are concerned.

Maybe, just maybe its time to listen for footsteps. The last group of species to mess with the environment were the anaerobes almost one-billion years ago and just before the end they were so dominant and populous, numbering in the quintillions that it seemed like things would never change. But change they did and now they are just a fossil memory.