更新: 12/05/2014 分类: 托福机经
The maximization of parsimony (preferring the simpler of two otherwise equally adequate theorizations) has proven useful in many fields, and this article concerns its application to phylogenetics. Occam's razor, a principle of theoretical parsimony suggested by William of Ockham in the 1320s, asserted that it is vain to give an explanation which involves more assumptions than necessary. When applied to computational phylogenetics, maximum parsimony describes a particular non-parametric statistical method for constructing phylogenies. In this application, the preferred phylogenetic trees are the trees that suppose the least evolutionary change to explain observed data (hence maximally parsimonious). The basic ideas were presented by James S. Farris  in 1970 and Walter M. Fitch in 1971. Alternatively, phylogenetic parsimony can be characterized as favoring the trees that maximize explanatory power by minimizing the number of observed similarities that cannot be explained by inheritance and common descent. These two different points of view (minimization of required evolutionary change and maximization of observed similarity that can be explained as homology) may result in different preferred trees when some observed features are not applicable in some groups that are included in the tree, and the latter can be seen as the more general approach.
While evolution is not an inherently parsimonious process, centuries of scientific experience lend support to the aforementioned principle of parsimony (Occam's razor). Namely, the supposition of a simpler, more parsimonious chain of events is preferable to the supposition of a more complicated, less parsimonious chain of events. Hence, parsimony (sensu lato) is typically sought in constructing phylogenetic trees, and in scientific explanation generally. However, complications in both actual evolutionary processes and in the methods used to reconstruct them make