Explaining the punctuation of equilibrium
The April, 2010 edition of Discover Magazine profiles biologist Lynne Margulis, famous for her well accepted suggestion that eukaryotic bacteria did not evolve in linear fashion, solely as as a result of natural selection. Rather,
mitochondria and plastids--vital structures within animal and plant cells--evolved from bacteria hundreds of millions of years ago, after bacterial cells started to collect and interactive communities and live symbiotically with one another. The resulting mergers yielded the compound cells known as eukaryotes, which in turn gave rise to all the rest-the protoctists, fungi, plants and animals, including humans.There was a shocking idea at the time (1967), but, as described in this article by Dick Teresi, the more recent ideas of Margulis are even more controversial. The Discover Magazine article documents her arguments that symbiosis is "the central force behind the evolution of new species." This position runs counter to the holding of modern conventional scientific wisdom, that new species arise through "gradual accumulation of random mutations, which are either favored or weeded out by natural selection." Margulis holds that random mutation and natural selection play a minor role and that the big leaps in the evolutionary record "result from mergers between different kinds of organisms, what she calls symbiogenesis." The Discover article takes the form of an interview, in which the dominant theme is that "natural selection eliminates and maybe maintains, but it doesn't create." Margulis argues that the laws of genetics "show stasis, not change." She was prompted by the fact that there is no record of major fossil change until 542 million years ago, yet all of a sudden we see the Cambrian explosion. Stephen Jay Gould coined this phrase, "punctuated equilibrium," "to describe a discontinuity in the appearance of new species." According to Margulis, her explanation of symbiogenesis explains these discontinuities and should thus be considered the primary mechanism for evolution. Margulis carefully distinguishes her approach from arguments based on "intelligent design." She holds that those who advocate for "intelligent design" have nothing meaningful to offer to the scientific conversation. [More . . . ]