University of Chicago (Medicine department) has a report about Sardinia genetics - h/t Jessica Saraceni. Specifically, the Chicagoans've sequenced Nurag[h]ic DNA. These are the islanders of Sardinia after the ocean rose to split Sardinia from Corsica 5000 BC, and before the Sea Peoples 1200 BC.
It was already projected that Nurag-DNA should look like Oetzi DNA. Oetzi was Chalcolithic south-European villager DNA, pretty much like [UPDATE 3/16 - 60% of] Sardinian DNA today except with (even) less R1a, R1b, X (for women) and other Yamnaya markers. One often finds a surprise with these things so, even if there weren't surprises this time, I'll grant the necessity to go look. Since the genetics are nailed down, I'm moving on to the language.
Sardinia speaks Latinate (if nonItalian) today - which demands an answer. The Euskara in 200 AD and the Rasna in 700 BC are each recorded as speaking entirely non Indo European tongues (mutually unrelated). The Basque base population was maternally "Helena", but now their menfolk are heavily R1b like me.
The Etruscans switched to the Villanova culture which was culturally Urnfield / LepontoGaulish, so were presumably R1b as well. And plenty other "berber" languages survived in Spain and of course in North Africa. Where the languages did move to IndoEuropean, as in Britain, it was accompanied by what is politely termed "high population turnover". So where old pagan Europe let the women live, the women tended to win the war at home. But not in Sardinia.
To explain how Sardinia exchanged language and not genetics, I propose: that Sardinia had a longer experience with Italic languages, specifically with paraLatin languages, than is usually assumed. [UPDATE 3/17: Hoo boy, I really should have read moar...]
It starts with a look at the map and a thought to Mediterranean ship technology. Well into the Age Of Iron, ships were too unstable to support longlasting foreign colonies. It wasn't until, what, 800 BC when Tyrians could seed Carthage and Utica - and Olbia, in northwest Sardinia (later taken by Iolaus, an Attic Greek pirate). Also in the 800s is when a Villanovan - GalloEtruscan - colony is known off Sardinia's coast, at Tavolara. Before then, northern Italians were left alone for a millennium or more in the Corsican strait.
The next question is, which Italians.
The northeast coast of Sardinia is of course closest to Corsica; in our times the last Bourbons found northern Sardinia speaking Corsican and not Sardinian. Corsica was nigh to the southern reach of Etruria - as of 540 BC, when the Etruscan city Caere conquered that island. By the same token Corsica was also close to Rome and to old Faliscia.
This blog has proposed a model where Italic languages had broken from protoCeltic and got to the ankle of Italy (which Villanovans never did) even before the Avellino eruption 1700 BC - starting Inca-like from the hills. The heel might have been Messapic and Dorian-facing but Sardinia doesn't care. Whatever was spoken at the Calabrian toe as of 1700 BC, Sardinia also wouldn't have cared - it's far away across open ocean.
As of the 800s BC and maybe even as of 1300 BC the Latium-Faliscia region spoke its own languages, related to the Oscan of the hills east and south. As the Etruscans only got to Corsica in the 800s BC, so also they hadn't reached as far as Latium until around that time. Their kings ruling Rome didn't replace the Latin language except at temple.
I suggest that Latin / Faliscan languages were dominant in the "Tuscan" archipelago - particularly Elba - until the Villanovan invasion. The eastern coast of Corsica would by then have needed some Latinish pidgin to trade with the mainland. When the Rasna claimed those entrepots, they ruled them like they were ruling Rome. This meant maintaining the local trade-tongue, although some Rasna writing has been uncovered in Etruscan-era Corsican cities.
That island trade-tongue would by 400 AD not even have been a creole anymore; it was accented paraLatin. More: Corsica had nothing to stop paraLatin from capturing the main routes internal. Almost all Corsica was Latin-speaking, or near enough, full centuries before Rome asserted primacy over the Latin Speaking Peoples.
As for northeast Sardinia at this time: the bulk of the island's coastline came under "Punic" influence, and indeed UChM's paper finds Levantine DNA here succeeded by (North) African. No part of Sardinia ever saw reason to move to the Rasna language. The northeast of Sardinia, close to Etrusco(-Latin) Corsica, would then keep on keepin' on.
So by the time of the First Punic War, first the Rasna and then the Romans could already count on a Roman-like native population on at least the eastern shores of those islands. I would extend this reach as far as Sardinia's northeast coast. Think how the Normans found twelfth-century Dublin.
CONSTRAINT 3/16: For most of Sardinia, let's not underestimate that Punic takeover. The North Africans and, to a lesser extent, the Greeks were by far the most drastic event ever to hit the islanders. Thus making my comment "shifting language but not genetics" very, very wrong. Although this blogpost does still work for Corsica.
