In Prehistory, Paleolithic stone toolkits are allotted to distinct cultural phases, explained through a periodization that has been adopted as a strategic reference by specialists in lithic studies, based on: 1) the categorization of morpho-types observed in the assemblages; 2) the dominant manufacture technologies and 3) temporal categorizations based on geo-archeological data. Significant changes in toolkits are observed through time, signaling variations in extinct hominin behavioral configurations. They characterize the denominative classifications of the techno-complexes, presently defined under consensus. Applying the Homogeneity, Variability, Diversity, Multiplicity (HVDM) paradigm as a conceptual scheme for understanding the structural evolution of human technologies, we define the Multiplicity phase, exploring the techno-social consequences of changes materialized in the Late Acheulian of Western Europe, presaging the Middle Paleolithic world of the Neandertals and the arrival on the scene of our own species; Homo sapiens. During this period, in Western Europe, Homo heidelbergensis was undergoing biological transformations, which appear to have fused into a range of hominin forms, raising questions of intra-species contacts and cultural exchange on a backdrop of branching evolutionary configurations. Beyond handaxe production, this period is marked by significant social and behavioral revolutions: changes in landscape use, high population mobility and inter-connectivity, tool-type diversity, technological innovations, as well as the expansion of distinct hominin clades throughout the Old World. We examine the impulses for these changes, in particular, the prominent role played by the mastery of fire in revolutionizing human socialization processes.