J. A. Barnes pointed out that, because patrifiliation is a condition for inclusion in highlands' groups, there may be superficial similarities between them and groups described as lineages in the African literature. What it is not difficult to find are groups for inclusion in which patrifiliation is a merely sufficient condition, and that difference accounts for many of the ways in which social groups and intergroup relations in the highlands differ from genuine patrilineal descent groups and their interrelations elsewhere in the world. The one genealogical relationship that is formally related to group constitution is patrifiliation, and logically this implies that not only a man and his children but also paternal brothers are members of the same group, at least until one or more of them decide to arrange otherwise. Groups may quite legitimately vary from place to place and time to time, and depending on various local economic and ecological or political conditions, in readiness to accept immigrants.