M-W: the quality of being very unwilling to spend money

(Middle English parcimony, from Latin parsimonia, from parsus, past participle of parcere to spare).

  1. the quality of being careful with money or resources: thrift: the quality or state of being stingy
  2. economy in the use of means to an end; especially: economy of explanation, in conformity with Occam’s razor

Occam’s razor is often referred to as the “Law of Parsimony”.

In phylogenetic reference, the parsimony principle is to look for the simplest explanation to fit the scientific evidence. The principle has been used in various fields of endeavour in likewise fashion.

In the analysis of phylogeny, parsimony means that a hypothesis of relationships that requires the smallest number of character changes is most likely to be correct. In molecular systematics, these character changes are DNA mutations.

A graphical illustration of ancestral reconstruction by maximum parsimony [Wikimedia Commons]
This relation-type diagram is known as a cladogram (Greek clados “branch”, and gramma “character”)

In the context of ancestral reconstruction, parsimony endeavours to find the distribution of ancestral states within a given tree which minimizes the total number of character state changes that would be necessary to explain the states observed at the tips of the tree.

Here is another example of a cladogram:

We could argue this cladogram’s merits ad-infinitum. Instead, let me refer you to a primer on primates.

There we go: our nom du jour has taken us from parsimony, to plant pollination, to primate. What a wonderful world.


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