Conway Morris Simon
University of Cambridge, Department of Earth Sciences, Downing Street, Cambridge CB2 3EQ, UK.
Philos Trans R Soc Lond B Biol Sci. 2006 Jun 29;361(1470):1069-83. doi: 10.1098/rstb.2006.1846.
The Cambrian 'explosion' is widely regarded as one of the fulcrum points in the history of life, yet its origins and causes remain deeply controversial. New data from the fossil record, especially of Burgess Shale-type Lagerstätten, indicate, however, that the assembly of bodyplans is not only largely a Cambrian phenomenon, but can already be documented in fair detail. This speaks against a much more ancient origin of the metazoans, and current work is doing much to reconcile the apparent discrepancies between the fossil record, including the Ediacaran assemblages of latest Neoproterozoic age and molecular 'clocks'. Hypotheses to explain the Cambrian 'explosion' continue to be generated, but the recurrent confusion of cause and effect suggests that the wrong sort of question is being asked. Here I propose that despite its step-like function this evolutionary event is the inevitable consequence of Earth and biospheric change.
寒武纪“大爆发”被广泛认为是生命史上的关键转折点之一，但其起源和成因仍极具争议。然而，来自化石记录的新数据，尤其是布尔吉斯页岩型特异埋藏化石库的数据表明，动物形态的形成不仅在很大程度上是寒武纪的现象，而且已经有相当详细的记录。这与后生动物起源更为古老的观点相悖，目前的研究正在努力调和化石记录（包括新元古代晚期的埃迪卡拉生物群）与分子“时钟”之间明显的差异。解释寒武纪“大爆发”的假说不断涌现，但因果关系的反复混淆表明我们提出了错误类型的问题。在此我提出，尽管这一进化事件具有阶段性作用，但它是地球和生物圈变化的必然结果。
