Death creates life

Posted 14 March 2008

In prehistoric times, the Earth was hit by a hailstorm of meteorites with a belt of dust that subsequently covered the planet. But instead of killing all life on Earth, the exact opposite occurred. Biological diversity increased in the wake of all these meteorite impacts, shows new research from the University of Copenhagen, which has been published in the international British scientific journal Nature Geoscience.

Meteorite impacts are often associated with huge disasters, mass extinction and why the dinosaurs disappeared from the face of the Earth some 65 million years ago. However, the opposite may also occur – that new and more varied animal life arises following such a catastrophe, is shown by new research conducted by the Natural History Museum of Denmark, University of Copenhagen.

Meteor rain changes life on Earth

Together with colleagues from Lund University in Sweden, two palaeontologists, Svend Stouge and Dave Harper, have discovered that the Earth in the so-called Ordovician period 490-440 million years ago was struck by more than 100 meteorites at one time, and that in the wake of this event, new and more varied life evolved in the oceans, which at that time were home to virtually all life on Earth.

“You could say that biological evolution experienced a serious boost within a relatively short period of time. And, as is the case with, for example, volcanic eruptions or large forest fires, the impacts initially had a devastating effect on all life, but from the ashes arose a much richer fauna than had existed previously. And another interesting aspect is that this situation occurred 40 million years after the so-called Cambrian explosion. It was during this explosion that the first complex multicellular creatures appeared, even though scientists are still discussing whether this evolution was a rapid explosion or whether it took place over a longer period of time,” says Dave Harper from the University of Copenhagen.

The conclusions of the two scientists are, among other things, based on computer analyses, chemical samples from meteorites, fossils and examination of different craters in Sweden, for example the large Lockne crater near Østersund in northern Sweden, which has a diameter of 7.5 km.

“So far, our research has shown that it was a regional phenomenon around Baltica, the Baltic Sea of that time. The area underwent an extraordinary change during a short period of time in terms of the evolution of new species, primarily shellfish, e.g. the so-called brachiopods, which resemble today’s mussels, but which already at that time were quite different. We will now be studying whether this was a global phenomenon. It will be really exciting for the entire history of evolution, especially as it does seem that there is some truth in it and in the impact theory. We have now found meteorites in southern China with the same chemical composition as those we have studied in Sweden. Consequently, we are going to be studying craters and meteorites in China and in the USA to establish whether it was a global phenomenon,” says Svend Stouge from the Natural History Museum of Denmark.