Centriole evolution.

Centrioles are cylindrical structures found at the core of the mitotic spindle pole, which also act as basal bodies to nucleate the formation of cilia. Centrioles have a complex, ninefold symmetric structure, and reproduce by an intriguing duplication process. The complexity and apparent self-reproduction of centrioles raises the question of how such a structure could have evolved, making them a favorite topic for theological speculation by 'intelligent design' creationists. In fact, centrioles are capable of robust self-assembly and can tolerate dramatic perturbations while still maintaining basic functionality. Far from being irreducibly complex, centrioles appear to be based on a rather minimal underlying core structure requiring only a handful of genes to construct.