How Could a Civilization that Managed to Sail to an Island forget how to make boats?

The Canary Island aboriginal people, the Guanches, are a perplexing mystery to enthusiasts as myself and many anthropologists. There are seven “main” islands and several smaller ones that together make up the Canary Islands, and the one closest to the African mainland is about 350 miles off the African coast, and a brief look at the continental shelf on the west coast of Africa shows that this distance wouldn’t have been that much smaller when the sea levels were much lower 10,000+ years ago, let alone 5,000 or so years ago when the sea level was pretty much the same as it is now.

How could a culture that managed to get to the Islands beyond the horizon of the African coast (from Africa, it is assumed), and managed to settle all of the seven main islands lose knowledge of navigation by sea to the point that they couldn’t even build boats, to the point that not only had they lost connection with the mainland, but the islands had become isolated from each other as well? The former is somewhat conceivable, since the mainland was beyond the horizon, but from any of the seven islands, at least one of them is visible in the horizon in plain sight. Furthermore, most of the islands had abundant forests, which the islanders used to make fire, and it is certain that the boats that they had come on would have been made of wood, so how could they not connect the dots and at least try to build boats? And how could this knowledge be lost or be allowed to not be passed down with utmost care?

One last question: Were the Polynesian seafarers in Easter Island able to leave their island by boat by the time they were visited by Europeans? I recall reading in Collapse by Jared Diamond that they had cut down all of their trees and were therefore unable to build boats (wood logs rot quickly?). I am not sure of whether the problem was that 1) they knew how to navigate the waters, but they couldn’t build the boats needed to do so since they had cut down all of their trees 2) even if they didn’t cut down the trees, they had lost the knowledge of boat building by that time so they wouldn’t be able to make boats anyway.

Good questions. With regards to the Easter Island situation, no, the islanders couldn’t build wood boats (they could build reed boats) when they cut down all the trees, but that may have been only part of the problem.

My thought is that by the time of Cook or much earlier, they realized how isolated they were and how risky an ocean voyage was. Up to the settlement of Easter Island from Polynesia, all previous islands were far closer together and much less of a risk. It’s amazing that Easter Island was settled at all. So they were unlikely to want to venture out when land was still habitable (barely).

That doesn’t explain the Canary Islanders, however.

My understanding, regarding the Polynesians, is that the knowledge is not so much how to build boats, but how to navigate solely by stars.

I had the pleasure of spending some time on the Hōkūleʻa (one of the few existing voyaging canoes) with the star-navigation master Nainoa Thompson. The knowledge of how to navigate by stars is what is critical. Even now, there are very few people who can actually navigate the Pacific Ocean by stars. A Melanesian woman I knew who did a transpacific trip in the Hōkūleʻa had a great-great uncle back home on the islands who still remembered how to voyage from oral tradition, but he is the only person I had heard of learning from his ancestors, and not from an educational organization (like the Polynesian Voyaging Society).

My understanding is that celestial navigation was important, but by no means the sole method - it was augmented by:

Knowledge of clouds - in particular, the ability to locate an island when it was well out of sight by the clouds that tend to form near and over it

Understanding of ocean swells and the way they are influenced (e.g. diffracted) by shallow water and land

Knowledge of birds and their flight patterns

All I know is that loss of technology in small, isolated populations is extremely common.

A sailor friend of mine told me Polynesians in the open sea could find the direction of a current by jumping overboard naked and feeling it on the most sensitive part of their body–the scrotum. It sounds nuts, but if it’s true, that’s one skill that’s been lost to most modern sailors.

Was that deliberate? :dubious:

Yes; small, isolated and almost as important, pre-literate. All is takes it for the few people who know how to do or make something to die without passing it on, and that knowledge is just gone. There’s no one to ask how to do it and no books to consult.

Taking a sounding, so to speak.

Heck, I don’t know how to make a boat, so who am I to point fingers at anyone else?

I’m guessing people in the Canary Islands lost that knowledge for the same reason I did - it didn’t seem like something they really needed to know. Presumably, the average Guanche was reasonably content on his island and didn’t feel any urgent need to travel to somewhere else. (And the Guanches who did feel the urge to travel presumably left the islands and went somewhere else.) In a pre-literate society it takes a lot of ongoing effort to maintain a set of skills. A general lack of interest and society loses those skills in just a couple of generations.

The Tasmanians are another example of a society that lost significant amounts of technology after settling from the mainland.

What about the Norse Greenland colonists? The Vikings settled Greenland, around 1000 AD. By AD 1450, they were gone. Now, Greenland has no wood (apart from driftwood), and Greenland was regularly visited by ships from Iceland and Norway-one would think that history would have recorded a massive reverse migration from Greenland-but it doesn’t. Somehow, a few thousand colonists vanished in the space of a few years-were they unable to leave because they had no boat building capability? The question has never been answered.

Regarding the ancient Hawaiians - I read they, too, lost the ability to make long-distance ocean voyages after some time of settlement. They were able to make inter-island journeys for trade and war using canoes, but eventually lost trade contact with Tahiti (which, I understand was accomplished during the earlier years of settlement), and then were not able to sail beyond the sight of land. The next long-distance-ocean voyager to see Hawaii was Captain Cook.

Pretty much this. OP, do you know how to do everything your parents, grandparents, great grandparents… knew how to do?

I don’t know how to milk a cow, though my grandparents owned a dairy farm. I don’t know how to repair a TV, though my father worked as a TV repairman in his youth.

If there’s no economic pressure to keep a skill (if, say, the long-distance sailors can’t make as much money as people who stay on the island), it’s going to disappear pretty quickly.

Times of turmoil also help… According to Diamond, the final frenzy of statue making came to a head, so to speak, with a complete breakdown of the old order, civil war, and things go so bad the society collapse (hey, great name for a book!) resulted in a loss of more than half, possibly 90% of the population, cannibalism, etc. Not the best time to be learning the old ways and practising how to dig out canoes from non-existent logs.

A lot of this is very speculative and debatable, but apparently the best they could do for fishing canoes by the time Europeans arrived was chunks of wood laced together. Not to worry, the Europeans rounded up a lot of them and gave them a lift to Chile to sell as slaves.

Come to a head. Hahahahahaha. Get it…a head? Awwww nm

Well, at least they had a happy ending.

I wonder if prevailing wind patterns have something to do with it as well. It’s a lot easier to make a boat sail downwind than upwind. The Canaries look to be in the right latitudes for the trade winds, predominantly east-to-west. Getting from the mainland to the islands would be easier than getting back.

supery00n, how much do you know about the history of the Canaries? After they were settled, was there regular contact with people from mainland Africa for some time? If that contact stopped, it seems that not only did the islanders lose the ability to travel to the mainland, but the mainlanders lost the ability (or the interest) to visit the islands.

And how skilled were they at making tools? You say there was plenty of wood on the islands to make boats out of, but you need other things, too. Maybe they only brought one ax from the mainland when they settled. Once that wore out, all the trees in the world aren’t going to help you build a boat.

Not much to add other than that the first counter-question that popped into my head is 'how could a country that flew to the moon forget how to get back?" I’ve head those urban legends about how if we wanted to get back tomorrow we’d pretty much have to re-learn everything as the data is stored in inaccessable ways and the engineers are all dead or dying.

Going back to Jared Diamond’s Collapse, the by far most likely explanation is that they had a bad winter, lost too much livestock, and either all starved before the yearly ship reached them, or were too weak to fight off an Inuit attack.

He provided much, much evidence that that colony was always extremely marginal, so it’s not that surprising that a single bad winter was enough to wipe it out. Since the visiting ship didn’t write down any specifics about exactly what they found (they just mentioned they didn’t find any colonists and left it at that), that’s probably as good an explanation as we’ll ever get.

On the other hand, the Norse Greenland colony lasted longer than the British American colony has, to date. Not exactly a bad job.