Mass extinctions had multiple events
26 October 2006
by Carina Lee
Big extinctions, such as that which killed off the dinosaurs, aren’t single simple events like a volcanic eruption, meteor impact, or cosmic rays. This is according to a study conducted by researchers of Hobart and William Smith Colleges, Geneva, New York. The new proposed theory is called the pulse-press theory, derived from Ian West and Nan Crystal Arens’ compilation of geological time periods of when species suddenly disappeared off the face of the Earth. The theory suggests two things could have happened together to cause these mass extinctions. One is that sudden catastrophic events may have wiped out communities quickly (pulse) in conjunction with placing a steady pressure on species over that period of time (press). West and Arens carried out the research by sifting through the geological record and looking, in particular, at marine genera. They marked the times where pulses and presses occurred separately, where they both occurred at the same time, and where neither of them occurred. They studied this pattern and found that a statistically higher percentage of genera went extinct during times of pulses and presses combined. It is interesting to compare these results to what is currently occurring in the environment we live in today. West explains “We came up with the idea that humans themselves act as both Press and a Pulse. Humans began manipulating the environment - the Press - from the advent of agriculture. However, that alone did not trigger the current mass extinction. That seems to have been triggered by the pulse of industrialisation and the demands for energy and resources that came with it.” |
More than a single event is needed for extinctions image:NASA and USGS |
Related Links
Original press release from EurekAlert
Nature
& Science News
ClearlyExplained.com