What is Basal?
''''Basal'''' is a term in [[biology]] for 'primitive' or 'ancestral'. Basal is preferred because it is neutral and non-judgmental. This terminology came into use with [[cladistics]]. The term is used in [[evolution]] and [[classification]] to mean the group which gave rise to later forms. It is a term which works at any level: a basal [[species]] gives rise to '''derived''' species, and a basal group gives rise to derived groups. ''''Derived'''' is the correct term in [[biology]] for ''specialised'' or ''advanced''. It is used for groups which have evolved from a more basal group. A '''derived trait''' is a [[Trait (biology)|trait]] that is present in an organism, but was not in the last [[common ancestor]] of the group being considered. Simplicity is often secondarily derived.<ref name=Clark1999>{{Cite journal | last = Clark | first = C.G. | year = 1999 | title = The effect of secondary loss on our views of eukaryotic evolution | journal = The Biological Bulletin | volume = 196 | issue = 3 | pages = 385–388 | doi = 10.2307/1542976 | url = http://www.biolbull.org/cgi/reprint/196/3/385.pdf | publisher = Marine Biological Laboratory | jstor = 1542976| pmid = 28296494 }}</ref> For example, no [[mitochondria]] in the anaerobic [[protist]] ''[[Entamoeba histolytica]]'' is a result of their secondary loss. ;General view – *Basal group **Derived group **Derived group **Derived group ;Example – *Early [[primate]]s **[[Monkey]]s ***[[Ape]]s ****''[[Homo]]'' In the last example, note that apes are ''derived'' from monkeys but ''basal'' with respect to our own [[genus]]. The status of being basal or derived is relative, though living species can only be derived. In any basal-derived pair, the basal member must have evolved before the derived member, with evidence that some of its species gave rise to (evolved into) the derived member.<ref>{{cite web|url=http://tolweb.org/tree/home.pages/treeinterpret.html|title=Interpreting the tree diagram or list of subgroups on a Tree of Life page|publisher=Tree of Life web project}