In this series, we reexamine the claim made by Intelligent Design proponent Michael Behe to have found a limit to “Darwinian” evolution in light of recent results from the laboratory of Richard Lenski.

One consequence of speciation being a population event is that populations have genetic diversity – not all members of the population are genetically identical. For any particular gene, then, a population may have several slightly different forms present within it. These different forms are called alleles.

In this series, James Kidder provides an intriguing study on transitional fossils and the evolutionary history of modern humans. He begins by discussing the fossil record, explaining how new forms are classified. He then explains the physically distinguishing trait of humankind—bipedalism. From the discovery of Ardipithecus, the earliest known hominin, to the australopithecines, the most prolific hominin, Kidder focuses on the discovery, the anatomy, and the interpretation of these ancestral remains.

Many evolutionary critics have identified the Cambrian Explosion as a stumbling block to the theory of evolution, arguing that the “expected transitions between major invertebrate phyla are absent, and that the suddenness of their appearance in the fossil record demonstrates that evolutionary explanations are not viable.” Keith Miller argues that the Cambrian Explosion is not so problematic as these opponents claim after all.