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Dr. Andrew Knoll is the Fisher Professor of Natural History in Harvard University\u2019s Department of Organismic and Evolutionary Biology, where he studies ancient life, its impacts on the environment, and how the environment, in turn, shaped the evolution of life.\xa0 In recognition of the 200th anniversary of Charles\u2019 Darwin\u2019s birth and the 150th anniversary of the first printing of his book, \u201cOn the Origin of Species\u201d, the American Society for Microbiology has invited Dr. Knoll to deliver the opening lecture, titled \u201cMicrobes and Earth History,\u201d at the society\u2019s general meeting in Philadelphia this year.

Before the dinosaurs, before trees and leaves, before trilobites, there were microbes.\xa0 Vast, slimy layers of them covered the rocks and peppered the seas of the harsh, alien planet we now call Earth.\xa0 Those slimy cells were our ancestors, and they played a defining role in changing that once-barren moonscape into the world we see today: a planet covered with diverse, striving life, topped by an oxygen-rich atmosphere.\xa0 Dr. Knoll says he puts on his paleontologist\u2019s hat and studies the fossil record to learn more about this ancient life, then he dons his geochemist\u2019s hat to reconstruct Earth\u2019s environmental history from the chemical signatures he finds in ancient sedimentary rocks.\xa0 He weaves these two stories together to figure out how life has transformed the planet and how the planet has influenced the course of evolution.

In this interview, I talk with Dr. Knoll about what early earth must have looked like, his involvement with the Mars rover project, and how intelligent design concepts may well belong in high school curricula, but not in the context of science class.