This A.G. Kozintsev paper goes well with a lot of the stuff I've been posting lately about the early Indo-Europeans, Indo-Iranians and Scythians (see here and here).
The article presents some results of a multivariate analysis of 245 male Eurasian cranial series dating to various periods from the Neolithic to the Early Iron Age. These results contradict the commonly held view that certain comparatively gracile (narrow-faced) Bronze Age populations of Southern Siberia and Kazakhstan were “Mediterranean” in the anthropological sense, i.e. Southern Caucasoid. Craniometry provides no support for the theory that those people migrated to Southern Siberia or Kazakhstan from Southwestern Central Asia, the Near East, or Trans-Caucasia. Populations described as “Mediterranean” (the Okunev people of Tuva, the Yelunino, the Samus, and some Afanasiev and Andronov groups) display craniometric resemblance with the Bronze Age people of Southern Russian and Ukrainian steppes, as well as with certain Late Neolithic and Bronze Age groups of Central and Western Europe. These affinities are apparently caused by migrations of Indo-Europeans (specifically Indo-Iranians) from their European homeland eastward, as far as Eastern Central Asia. The return from Eastern Central Asia to Europe of the descendents of one of these groups during the Early Iron Age was probably the principal cause for the emergence of the Scythians on the historical arena.
A.G. Kozintsev, The "Mediterraneans" of Southern Siberia and Kazakhstan, Indo-European migrations, and the origin of the Scythians: a multivariate craniometric analysis, Archaeology, Ethnology and Anthropology of Eurasia, Volume 36, Issue 4, December 2008, Pages 140-144, doi:10.1016/j.aeae.2009.03.013