Mother Nature likes to do a clear-out every now and again, a phenomenon called mass extinction. We are in the midst of one now, and a British scientist believes that many large mammals, including us, are for the high jump.
Prof Michael Boulter, professor of palaeo-biology at the University of East London, has created a mathematical model which reflects the emergence, rise and eventual fall of species on this planet. It also factors in unexpected events such as a comet impact or rapid changes in climate. These can spark sudden mass extinctions.
Studies of the fossil record, which provides ancient clues to life on Earth, show that the fossils match the model, Prof Boulter told visitors to the British Association's Festival of Science in London, which closed yesterday .
The removal of species was a necessary process and reflected the way that life adapts on the planet, he said. "The patterns emerging from these calculations show that life on Earth needs the occasional cull."
The mass extinctions caused by impacts with comets or asteroids were unpredictable but had the same net effect as the natural ones which were due to sudden changes in the environment or genetic mutations. After the dinosaurs were killed off 65 million years ago "life recovered, improved even", Prof Boulter said.
The mass-extinction event currently taking place does not quite follow the form, however. "Large mammals are becoming extinct at a very much higher rate than the curve predicts," Prof Boulter said.
"In North America up to 50 mammal families have become extinct over the last 20 million years and 20 more over the last 300,000 years. And that's before humans started to burn fossil fuels."
Things don't look so good for us given the tenor of the current mass extinction, although Prof Boulter would not be drawn on when exactly humans should be ready to hang up their boots. Humans were adding to the pace of the present species loss, which will involve all large mammals and many other groups, he said.
When our turn will come on the extinction merry-go-round is uncertain but Prof Boulter is convinced that we will be on it eventually.
"Now we have the privilege of living through the revolutionary times of another cull, another mass-extinction event," he said. "We will be one of the extinguished species. The good news is that life on the planet will recover and peace will return to the environment."
