Eurogenes mentions in the comments to a recent post the following (open access) article, which despite non-standard terminology for what it calls the Hamangia culture sees that culture also known as the Cucuteni-Trypillian culture (a descendant of a first wave Neolithic Anatolian farmer descendant culture) as a primary source of agricultural knowledge, metal working and burial practices of the Sredniy Stog culture (ca. 5000 BCE to 3500 BCE). The Sredniy Stog culture, in turn, is a likely candidate for being the Proto-Indo-European culture, which would explain how these technologies and beliefs could have arrived without carrying Caucasian genetic influences with them.
In other words, this article really starts to connect the dots of early Indo-European origins, in a way that seems to fit with everything else that we know.
The Contacts of the Eastern European Steppe People with the Balkan Population during the Transition Period from Neolithic to Eneolithic
The transition from the Neolithic to Eneolithic in the Eastern European steppe was connected with the intensive contacts of people of the Azov-Dnieper, Low Don, Pricaspiy, Samara, Orlovka and Sredniy Stog cultures with the Balkan population and first with the Hamangia culture. The results of these contacts were some imports: adornments from copper, cornelian, marine shells and pots in the steppe sites and plates from the bone and nacre, pendants from teeth of red deer in the Hamangia graves. The Hamangia infuence in the burial rites of the steppe population was very important and caused to use stone in graves and above them, pits with alcove, new adornments of burial clothes. The strongest impact we have fixed for the population in northern area of the Sea of Azov, where the radical changes in the burial rite and the formation of a new Sredniy Stog culture took place. It was connected with the adoption of new religious elements connected with the formation of the centre of steppe metal working.
It is also notable that the Cucteni-Trypillian culture was a more or less direct successor (in a disruptive transition in which farmers overtook steppe people) in roughly the same geographic location to the (basically steppe) Bug-Dneister culture that in my opinion was probably the source for the band of men, who after a long migration, would become the Chadic people of Africa.