Lamarckian realities: the CRISPR-Cas system and beyond

In his target article, Koonin discusses the insights into the evolution of bacterial genomes provided by the CRISPR-Cas system. This evolved defense system is based on intrinsic processes of genome engineering which, as he argues, enable Lamarckian inheritance. In this commentary I discuss some historical and conceptual issues that pertain to Koonin’s analysis of this aspect of the CRISPR-Cas system, extending and qualifying his discussion.