position. This would have involved bilingualism, resulting in the adoption of Indo-Aryan languages by local populations. According to Parpola, local elites joined "small but powerful groups" of Indo-European speaking migrants. These migrants had an attractive social system and good weapons, and luxury goods which marked their status and power. Joining these groups was attractive for local leaders, since it strengthened their position, and gave them additional advantages. These new members were further incorporated by matrimonial alliances. Renfrew: models of "linguistic replacement" Basu et al. refer to Renfrew, who described four models for "linguistic replacement": The demographic-subsistence model, exemplified by the process of agricultural dispersal, in which the incoming group has exploitive technologies which makes them dominant. It may lead to significant gene flow, and significant genetic changes in the population. But it may also lead to acculturalisation, in which case the technologies are taken over, but there is less change in the genetic composition of the population; The existence of extended trading systems which led to the development of a lingua franca, in which case some gene flow is to be expected; The elite dominance model, in which "a relatively small but well-organized group [...] take[s] over the system". Given the small size of the elite, its genetic influence may also be small, though "preferential access to marriage partners" may result in a relatively strong influence on the gene pool. Sexual asymmetry may also be of influence: incoming elites often consist mostly of males, who have no influence on the mitochondrial DNA of the gene pool, but may influence the Y chromosomes of the gene pool; System collapse, in which territorial boundaries are changed, and elite dominance may appear for a while. David Anthony: elite recruitment David Anthony, in his "revised Steppe hypothesis" notes that the spread of the Indo-European languages probably did not happen through "chain-type folk migrations", but by the introduction of these languages by ritual and political elites, which are emulated by large groups of people. Anthony gives the example of the Southern Luo-speaking Acholi in northern Uganda in the 17th and 18th century, whose language spread rapidly in the 19th century. Anthony notes that "Indo-European languages probably spread in a similar way among the tribal societies of prehistoric Europe", carried forward by "Indo-European chiefs" and their "ideology of political clientage". Anthony notes that "elite recruitment" may be a suitable term for this system. Michael Witzel: small