Wetenschap - 3 februari 2012

Chaos in solar system is cause of mass extinctions

Once in 85 million years, life on Earth reaches a peak. Entire species become extinct almost simultaneously. Wageningen emeritus Piet van den Noort has a new theory to explain what happened.

Van den Noort is not the first to do so. Numerous theories have been put forward in the course of time to explain all those extinctions. But none of these explanations is conclusive. Agricultural economist Van den Noort thinks he has found the key: the chaos. His extinction theory - and accompanying formula - explains the time, size and frequency of all known extinctions.
Van den Noort's formula is actually a simple one. According to him, there is a link among mass extinction (L), the number of species (N), the number of mutations (M) and disastrous impacts (I). His formula is: L = aN + bM + cI (plus a statistical constant). The driving force behind this is mutations. Van den Noort expounds his ideas in the December issue of The Journal of Ecology and the Natural Environment.
Logistic growth
Van den Noort's ideas are based on the logistic growth theory. Under certain circumstances, this type of growth is manifested as instability and chaotic growth behaviour. Only by continuous mutation can species avoid extinction. Van den Noort demonstrated this in the mid-nineties in his book, Complexity and Survival. His formula adds a new chapter to this book.
But there is more to it. Van den Noort also explains what makes mutations vary across the various geological periods. The cause is chaos in the solar system. Chaos causes the elliptical orbit of the Earth around the sun to shrink and expand continuously in a chaotic way. The bigger is the orbit, the weaker is the radiation and therefore, the fewer are the chances of mutations and the more unstable is the growth. Moreover, a bigger orbit raises the chance of impacts from asteroids (the I in the formula). This can sometimes lead to mass extinctions.
Therefore, chaos in the solar system is the cause of mass extinctions. According to Van den Noort, fluctuations in the orbits of planets is a well-known phenomenon in astronomy. He even attributes the lack of life on Mars and Venus to this chaos. 'Any form of life on these planets is wiped out as a result. The Earth has been lucky. Life has never vanished completely from here. The lack of life on Mars and Venus in fact confirms my theory.'
The extinction formula however does not explain only what is past. It predicts to some extent also the next mass extinction. We don't have to worry about that, though. According to Van den Noort, that will only happen some thirty million years from now.