ABSTRACT
This essay illustrates a neglected feature of Professor Daryll Forde's work which seems fundamental for the comparative analysis of segmentary relations and processes in acephalous societies based on unilineal descent groups. In such societies segmentary principles of organization are manifest in the situationally variable alignments of collateral descent groups to form contraposed blocks of elastic scale and roughly equivalent strength, span, and genealogical status. The structural relativity of these social units and their relations presupposes the primacy of genealogical and local principles of collective differentiation. Yet in his accounts of Yakö society Forde has repeatedly shown how these preconditions of segmentary lineage systems may be qualified or obstructed by other principles of structural differentiation and collective alignment, such as age-grouping, corporate associations, or double unilineal descent (1938, 1939, 1961, 1963).
