Oct. 24-26, 2009, Yingjie Overseas Exchange Center, Peking University, Beijing, China中文版

Darwin's headache, caused by the Cambrian explosion

Stefan Bengtson

Swedish Museum of Natural History

Abstract

For Darwin, the sudden appearance of advanced animals in the fossil record was a major problem for his theory of evolution. He attempted to explain the lack of a visible prehistory by calling on the incompleteness of preservation of the crucial rock record. This explanation he himself regarded as unsatisfactory, and we now know that he was on the wrong track: The Cambrian explosion was a real biological event, a radical reconstitution of the biosphere, not a fluke of preservation. Darwin's headache is still with us, however, but in other forms. We are still far from a satisfactory explanation of the Cambrian explosion. For example, the origins of multicellularity, non-bilaterians and bilaterians are all contentious problem sets where expectations have frequently forced the interpretation of fossil data. Although our knowledge and understanding of the events leading up to the Cambrian explosion are immeasurably richer than Darwin's, his metaphor of the incompletely preserved volumes of books still has relevance.

Stefan Bengtson

Swedish Museum of Natural History

Biography

Stefan Bengtson spent the early phases of his scientific activities on the debris from the Cambrian explosion called "small shelly fossils". This work started in Sweden but soon took him to other places, in particular Siberia, China, and Australia. His focus remains on the origin and early evolution of animals, and in more recent times he has worked on the embryology of early animal fossils as well as evidence of multicellularity in the older parts of the Proterozoic fossil record. He is Professor of Palaeozoology at the Swedish Museum of Natural History and Fellow of the Royal Swedish Academy of Sciences.