There's one thing that doesn't quite add up. If a gradual loss of seafaring technology was the reason for the islanders' isolation then the people on the African coast must have lost that technology as well. Otherwise people would have continued to travel from Africa and reintroduce the technology to the islands.
It seems extremely unlikely that the technology was gradually and seperately lost on both sides.
The Canary Islands are off the coast of West Sahara. That’s the most sparsely populated area of Africa today.
Maybe, as the desert expanded, the seafaring people moved north and south to more hospitable places. Leaving nobody in West Sahara to recontact the Canaries.
You don't have to guess, because that part of history is well documented. During the middle ages, present-day Morocco all the way to the latitudes of the Canary Islands was often controlled by major powers, such as the Umayyad Caliphate, the Almoravids, and the Almohad Caliphate. They were all naval powers, but their interests were elsewhere.
The people on the mainland didn't lose the technology. They lost the interest.
Ancient Mediterranean was full of naval cultures. But when the Roman Empire declined and fell in the west, maritime trade declined as well. Then Arabs conquered North Africa, turning the Mediterranean into a battleground. Nobody cared anymore about some remote sparsely populated islands.
"The African coast lies 124 km from the highest point on Fuerteventura, Pico de La Zarza, and 97 km from the closest point on Fuerteventura, Punta La Entallada. Assuming a height of ~ 100 m for land near the Moroccan coast (there are no mountains close to the coast), the predicted visibility ranges are 137 km from Pico de La Zarza and ~ 90 km from Punta La Entallada (and ~ 100 km from a peak just inland of Punta La Entallada). Africa should therefore be visible from at least Pico de La Zarza, on a clear day. "
The article clearly says that the islands had nothing to trade. Why would people on the African coast sail to the islands at all? Much less trade away technology?
> It seems extremely unlikely that the technology was gradually and seperately lost on both sides.
In this case I'd say it's the exact opposite: on the islands, neighboring communities right on the horizon provided enormous pressure to maintain the ability. Continentals on the other hand have very little incentive. I'd rather say by the time islanders have lost the ability, continentals will most likely have lost it ten times over.
> Mitchell suggests the Amazigh settlers took to the sea to escape conflicts sparked by a drying climate or the Roman expansion
Maybe motivation for such a risky sea crossing was just gone. Besides there was probably a good chance one would get hit on the head and have their ship and produce/merchandise stolen by whistling Canary headbangers. All for what? A handful of barley and some odd purple dye?
It seems extremely unlikely that the technology was gradually and seperately lost on both sides.