"Evolutionary systematics" was popular among earlier neo-Darwinians, encouraging biologists to consider perceived adaptations in identifying related groups of organisms. With the rise of computers, numerical taxonomy became popular, relying on overall similarities. In the 1950s, W. Hennig developed phylogenetic systematics or cladistics, grouping organisms based on uniquely shared characters relative to less closely related groups. Some cladists, critical of neo-Darwinian theory, studied relationship patterns without considering evolution.