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Nineteenth Annual Darwin College Lecture Series 2004

EVIDENCE

Lecture 6   :   February 20th 2004

Evidence for Catastrophes in The Evolution of Earth and Life

Vincent Courtillot

Institut de Physique du Globe and University Paris

Biography |   Abstract  |   Printable Version

Abstract

The title of this lecture contains (almost) only four words, each of which could be a topic for a Darwin College series. With Darwin and Lyell (respectively), we have learnt that both Life (studied by Biology) and Earth (studied by geology) had mostly evolved slowly, at a rather continuous pace, over the immense depth of geological time. This world view has come to be known as "uniformitarianism", the main line of thought in these sciences to this day (and a very successful one in many respects). Cuvier's 18th century views of catastrophic episodes was all but obliterated. But, maybe in relation with a rather agitated social and political life, "catastrophism" has been resurrected in a modernized way in the last quarter of the 20th century. We shall review some of the Evidence for mass extinctions of Life, and eruption of gigantic lava flows (traps) at a few (geologically short) times of fast change. We shall discuss recent evidence that the dates of these events seem to often coincide. This may lead us to discuss the meaning of "Evidence" in such scientific endeavours. And to conclude that both Earth and Life (which are intimately related) most often proceeded smoothly as envisioned by Darwin ("survival of the fittest") and Lyell, but that a few brief catastrophes from time to time completely reoriented the course of biological and geological history: these were times of "survival of the luckiest". When is the next such event due? And shall we be lucky?

The lectures are given at 5.30 p.m. in The Lady Mitchell Hall, Sidgwick Avenue, with an adjacent overflow theatre with live TV coverage. Each lecture is typically attended by 600 people so you must arrive early to ensure a place.