The Science Biodiversity and Ecological Complexity Models of Extinction Extinction has played an important role in the development of life on the Earth. Of all the species that have lived here since life first appeared, somewhere between one in a thousand and one in a hundred is still living today. All the others, the vast majority, became extinct, typically within one to ten million years of their first appearance. It is important first to understand the nature of extinction in the fossil record, before one can undertake any modeling efforts to try to explain that extinction. In recent years a number of claims have been made about apparent trends in the fossil record of extinction which might point to interesting underlying dynamical processes in the biosphere.
Initial results indicate some interesting conclusions.
Some of the trends noted in the fossil record are probably real. From this he has shown that the distribution of the sizes of extinction events in the fossil record is indeed compatible with a power-law form, as Kauffman suggested. Newman and Eble are also investigating the possibility that some other characteristic behaviors seen in the fossil record may be artifacts of the gradual decline in background extinction during the Phanerozoic eon. Turning to the evolutionary and environmental processes that drive extinction, there has in the last ten years been considerable interest in modeling the effects of large-scale coevolution on ecosystems. In addition, the possible existence of coevolutionary avalanches raises intriguing questions about the way in which ecosystems organize themselves and about the closely related issue of extinction rates.