The origins and spread of domestic horses from the Western Eurasian steppes
nature.com
nature.com
This is a pretty big shift in the story of how the IE languages spread westward to Europe. It also would seem to firm up the timing of the spread as happening sometime not too much later than 4000BCE (when horses were domesticated) since the westward spreading peoples had horses, but horse culture hadn't become as central to their lives as it was with the eastern-migrating IE speakers.
> By contrast, DOM2 dispersal in Asia during the early-to-mid second millennium BC was concurrent with the spread of chariotry and Indo-Iranian languages, whose earliest speakers are linked to populations that directly preceded the Sintashta culture11,12,45. We thus conclude that the new package of chariotry and improved breed of horses, including chestnut coat colouration documented both linguistically (Supplementary Discussion) and genetically (Extended Data Fig. 8)
I can't see the Supplementary discussion, but the chestnut coloration is likely referring in part to the Vedic (1500BC) description of a red horse (aruṣa). There are also probably contemporaneous Avestan terms.
It's pretty neat that the early mention of a chestnut/red colored horse parallels the genetic distribution of that phenotype, if I'm understanding the article correctly.
Indeed, maybe even mutually intelligible, but we can never know for sure.
> Sanskrit has insane overlap in lexicon with modern Lithuanian
Not just lexicon but grammar also: they have very aligned case systems, for example.
In the case of Lithuanian what you are seeing however is an extremely conservative language. Many ancient IE languages, not just Sanskrit, have a lot of overlap with Lithuanian.
What the paper provides is a more detailed chronology and sequence of the events.
A large part of the Indo-European expansion in Europe and Asia happened after 2200 BC, and that phase of the expansion was simultaneous with the spread of the domesticated horses and of the chariots with spoked wheels, as shown in the paper.
It is very likely that in the areas where the Indo-Europeans arrived after 2200 BC, they were the first who brought there the horses and associated technologies.
However, there was an earlier expansion of the Indo-Europeans, about a millennium earlier, and this new paper shows that the early expansion preceded the domesticated horses. It is likely that during this early phase the Indo-Europeans were distinguished from their neighbors by having an economy based mainly on raising cattle, which allowed them to be more mobile, even if not yet as mobile as later, when the use of horses was mastered.
Also according to the paper, the use of horses and of spoked wheels appear to have originated in the Indo-Iranian branch, and then it spread from them to the other Indo-European branches, which were still in relative geographical proximity, and whose languages were not yet as differentiated as later, so mutual intelligibility probably still existed.
This is consistent with the fact that the Hittites, in the second millenium BC, still had instruction manuals about horses which were written by speakers of an Indic language, from Mitanni.