   The relatedness among species due to common ancestry can reduce the amount of seemingly independent evidence one has for or against any evolutionary hypothesis. Species with a recent common ancestor may have inherited the same trait from the ancestor, as opposed to evolving it independently of one another. Comparative methods help one assess the extent to which a set of related species provide independent evidence for or against a given evolutionary hypothesis (Harvey and Pagel 1991). The general awareness of the need to use such methods stems primarily from the initially narrower debate that took place within systematics in the 1960s and 1970s over how to create classifications of organisms that are “scientific” and as such, are transparent recipes that are accessible to others, instead of being “private” and non-scientific. This debate generated tremendous controversy (Hull 1988) and it spurred on the development of methods to statistically correct for dependence among species' trait values when assessing an adaptive hypothesis (Felsenstein 1985, Harvey and Pagel 1991). In addition, it became more widely understood that a claim that one trait evolved in response to another is enormously strengthened by phylogenetic confirmation; the history of trait acquisition must be consistent with the hypothesis (see Maddison 1990 and references therein).