The Celtic invasion into LBA Britain

I missed this talk 19 November: "Large-Scale Migration into Britain During the Middle to Late Bronze Age". David Reich. Maybe also N. Patterson.

The main Indo-European signifier in Western Europe is R1b. Wales, Ireland, and most of what's now southern England was R1b-L21 by 2000 BC. Wales / England remains heavily the L21 subset, as we go west (I am L21, my ancestry is Severn). So I was unaware of any genetic break from the Early Bronze Age to the Roman era.

This means IndoEuropean Britain was an Early Bronze Age phenomenon, I think drawn thither exactly by the best copper alloy-material available, namely Cornish tin. Back home in Europe protoCelts perhaps calling themselves Volcae had extruded into Bavaria by 1200 BC. Italic and (probably) Lusitanian, paraCeltic both, I think had got into central Italy and western Iberia some centuries earlier. Implying that the first British Indo-Europeans were also paraCeltic... at first.

The extent to which south Britain's IndoEuropean chieftains and druids kept in pace with the Continental Celts would depend on regular contact between south Britain and the northwest Continent (UPDATE 1/27 which we'll see in MBA-LBA plagues). To be kept in mind, historically France had the population advantage over Britain absent imports. England got as far as it did from AD 1100 through events like the Norman kings forcing imports from France, then the British Navy scouting the Caribs and Cape Cod, and finally the agricultural tech of the Industrial Revolution. "Paleolithic HVAC Technician" / @AccurateCaption wonders how lopsided the balance, when the "Vampire Of The Continent" couldn't batten upon her host.

So far I have been aware of a sharp break in southeast British material culture 900 BC. The value of bronze collapsed and its jewelry thrown away. For the British, I think, "LBA" ends here, not in 1200 BC as in the eastern Med.

Reich and Patterson are telling us that this economic break represented the tail-end of a racial break. Over 1000-875 "BCE" (sic), a signature bearing more Farmer ancestry than the old British genome rose to a full half of the south British population. These must have been migrants. They believe that this formed the vector for Brythonic Celtic. This means: before 1000 BC, Britain was an island.

After 875 BC, the insular / continental gene-flow stopped. Britain became an island again. Until the Caesar-era Belgae I suppose, but they're hard to distinguish from the Roman invasions close on their heels.

EPILOGOI -

I am unsure what the research says about Old Irish, a famously conservative Q-Celtic tongue, as of 900 BC; they will hit their worst bottleneck at the millennium's turn, perhaps mediated by Continental meddling and diseases. Which will culminate in that Roman embassy although I'd not set Drumanagh itself before the Flavians.

I am wondering now about Macsen, Spanish-born hero of Cambria; was his rebellion driven by Welsh physical hunger?

The I2a2-line as we know it, now German, started to return(?) into East Anglia later. Certainly after the Iceni were gone; into the Roman era "Boudicca" is a Celtic name, for what that's worth, but at least shows Old Brythonic as still a prestige-language in the insular southeast. We'll see that I2a2 M284 bump AD 117.