The strategy of merging similar behavioral coding categories together into one superordinate code for subsequent analyses (lumping) as against creating new categories to classify samples (splitting). Seemingly, the distinction was first expressed by Charles Darwin (1809-1882) in a letter to the botanist Joseph D. Hooker (1817-1911) in August, 1857. Darwin wrote: “It is good to have hair-splitters and lumpers. (Those who make many species are the ‘splitters’ and those who make few are ‘lumpers’.)” In evolutionary, the distinction is used to classify taxonomists as either ‘lumpers’ or ‘splitters’ depending on their penchant for recognizing commonalities (lumping) or differences (splitting) between organisms. In ethology, the derivation of direct observation protocols has always required a fine balance between lumping and splitting behavioral categories, with ethologists recommending a research strategy beginning with splitting rather than lumping. With perhaps tongue in cheek, splitters are accused of identifying more species than actually exist while lumpers endeavor to correct the resulting damage. Accordingly, lumpers are regarded as incapable of discriminating sub biology tleties in nature. More formally, and across a range of disciplines, lumping is taken to mean two things are in the same category unless there is some convincing reason to divide them and splitting two things are in different categories unless there is some convincing reason to unite them. This intellectual distinction is reflected in contemporary biology with massive amounts of information being generated with regard to genes, proteins and neural pathways, information that now requires integrative biologists (i.e., ‘lumpers’) to make sense of it. A clear example of the distinction is evident in knowledge about the primate cortex. Anatomically, it is highly diverse with more than 40 areas. In order to simplify such complexity in terms of its functional expressions, a ‘lumping’ distinction has been made between the dorsal and ventral streams that diverge from the extrastriate cortex resulting in the so-called two-visual systems hypothesis.
See Coding scheme, Ethology, Evolutionary biology, General theory of biological classification, Two-visual systems hypothesis