Gould关于Punctuated equilibrium的简介, 其中简单述说了寒武纪大爆发和地球历史:
在他的观点中,35亿年前地球开始出现单细胞生命:“life on the earth evolved quickly and is as old as it could be”,在地球历史的5/6时间里都是单细胞生命,一直到6亿年前出现多细胞动物,接着大爆发来到:
More curiously, all major stages in organizing animal life's multicellular architecture then occurred in a short period beginning less than 600 million years ago and ending by about 530 million years ago – and
the steps within this sequence are also discontinuous and episodic, not gradually accumulative
The subsequent main pulse, starting about 530 million years ago, constitutes the famous Cambrian explosion, during which all but one modern phylum of animal ]ife made a first appearance in the fossil record. ( Geologists had previously allowed up to 40 million years for this event, but an elegant study, published in 1993, clearly restricts this period of phyletic flowering to a mere five million years.)
Gould对生命历史的总结:“Three billion years of unicellularity, followed by five million years of intense creativity and then capped by more than 500 million years of variation on set anatomical themes”
We do not know why the Cambrian explosion could establish all major anatomical designs so quickly. An "external" explanation based on ecology seems attractive: the Cambrian explosion represents an initial filling of the "ecological barrel" of niches for multicellular organisms, and any experiment found a space. The barrel has never emptied since; even the great mass extinctions left a few species in each principal role, and their occupation of ecological space forecloses opportunity for fundamental novelties. But an "internal" explanation based on genetics and development also seems necessary as a complement: the earliest multicellular animals may have maintained a flexibility for genetic change and embryological transformation that became greatly reduced as organisms "locked in" to a set of stable and successful designs.
In any case, this initial period of both internal and external flexibility yielded a range of invertebrate anatomies that may have exceeded (in just a few million years of production) the full scope of animal form in all the earth's environments today (after more than 500 million years of additional time for further expansion). Scientists are divided on this question.
Some claim that the anatomical range of this initial explosion(寒武纪大爆发) exceeded that of modern life, as many early experiments died out and no new phyla have ever arisen. But scientists most strongly opposed to this view allow that Cambrian diversity at least equaled the modern range - so even the most cautious opinion holds that 500 million subsequent years of opportunity have not expanded the Cambrian range, achieved in just five million years.
The Cambrian explosion was the most remarkable and puzzling event in the history of life.
Moreover, we do not know why most of the early experiments died, while a few survived to become our modern phyla ...
关于寒武纪大爆发,引用一本大学生物教材的说法:
R.S.K. Barnes, P. Calow & P.J.W. Olive, The Invertebrates: A New Synthesis, pgs 9-10 (3rd ed., Blackwell Sci. Publications, 2001)
Most of the animal phyla that are represented in the fossil record first appear, 'fully formed,' in the Cambrian ...
The fossil record is therefore of no help with respect to the origin and early diversification of the various animal phyla."
Gould没有用化石有待发现、化石形成概率很小等低级借口来解释中间进化环节的证据缺失,而是诚实地用了很多‘don't know’,然后用他的间断平衡理论来解释。