Editing Phenetics (section)

==Difference from cladistics==
Phenetic analyses are "[[Unrooted tree|unrooted]]", that is, they do not distinguish between [[plesiomorph]]ies, traits that are inherited from an ancestor, and [[apomorph]]ies, traits that [[evolved]] anew in one or several lineages. A common problem with phenetic analysis is that [[basal (evolution)|basal]] [[evolutionary grade]]s, which retain many plesiomorphies compared to more advanced lineages, seem to be [[monophyletic]]. Phenetic analyses are also liable to be rendered inaccurate by [[convergent evolution]] and [[adaptive radiation]]. Cladistic methods attempt to solve those problems.

Consider for example [[songbird]]s. These can be divided into two groups – [[Corvida]], which retains ancient characteristics of [[phenotype]] and [[genotype]], and [[Passerida]], which has more modern traits. But only the latter are a group of closest relatives; the former are numerous independent and ancient lineages which are related about as distantly to each other as each single one of them is to the Passerida. For a phenetic analysis, the large degree of overall similarity found among the Corvida will make them seem to be [[monophyletic]] too, but their shared traits were present in the ancestors of ''all'' songbirds already. It is the loss of these ancestral traits rather than their presence that signifies which songbirds are more closely related to each other than to other songbirds. However, the requirement that taxa be monophyletic – rather than paraphyletic as for the case of the Corvida – is itself part of the cladistic method of taxonomy, not necessarily obeyed absolutely by other methods.

The two methods are not mutually exclusive. There is no reason why, e.g., species identified using phenetics cannot subsequently be subjected to cladistic analysis, to determine their evolutionary relationships. Phenetic methods can also be superior to cladistics when only the ''distinctness'' of related taxa is important, as the computational requirements are less.<ref>{{cite web |last=Lindberg |first=David R. |title=Principals of Phylogenetic Systematics: Phenetics |url=http://ib.berkeley.edu/courses/ib200a/lect/ib200a_lect09_Lindberg_phenetics.pdf |work=Integrative Biology 200A Principles of Phylogenetics: Systematics |publisher=University of Berkeley |access-date=10 October 2018}}</ref>

The history of pheneticism and cladism as rival taxonomic systems is analysed in [[David Hull (philosopher)|David Hull]]'s 1988 book ''Science as a Process''.<ref>{{cite book |author=Hull, David L. |date=1988 |title=''Science as a process: an evolutionary account of the social and conceptual development of science'' |location=Chicago, Illinois |publisher=University of Chicago Press}}</ref>