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Could a small isolated island without trees yield alternative resources that enable Polynesian-level seafaring technology?

The island of Rapa Nui (known as Easter Island in English) had an overpopulation problem. They also didn’t have any pigs, so a major source of food was deep sea fishing. So, when they ran out of trees they lost the ability to build fishing boats and lost access to the tuna and dolphin prey. This greatly amplified their resource problem.

Supposing they had gotten a handle on their social problems, controlled the population size and worked together. Alas, this new social order emerged from the crisis, so all the trees were gone before they got their act together. Into this culture was born a genius, capable of design and innovation.

How could they have regained access to seafaring technology? First of all, what alternative construction could be used to build boats? Before the existing boats wore out, they could be used to bootstrap the replacement resource usage. And more generally, what marine-based resources could have been used to supplant their technology and replace the traditional Polynesian methods?

Note that the island is so isolated that any expiditions to even rediscover other lands would require rebuilding the height of their technology first, and decades to acheive.

They must get what they need from the remaining life on the island, the paultry off-shore resources, and the deep sea.

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Boats can be constructed using leather or skin stretched over a frame constructed of (drift)wood, bone or other materials (metal, for example). The Aleuts lived in a situation similar to or worse than the one you describe and were successful sea-farers (see Aleutian Kayak).

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  • $\begingroup$ This is what I would say, presumably if they are hunting dolphins then they could use the bones and skin (maybe some of whatever​ wood they have left) to make simple boats. Maybe not enough to reach other islands but enough to keep fishing and survive $\endgroup$
    – adaliabooks
    May 31 '17 at 8:49
  • $\begingroup$ It is possible to cross the Atlantic in a sea kayak, let alone reach a nearby island. $\endgroup$
    – Michael Vehrs
    May 31 '17 at 9:46
  • $\begingroup$ there are no large animals on the island to get leather from, and they need boats to hunt dolphins so it's a catch 22. $\endgroup$
    – John
    May 31 '17 at 19:01
  • $\begingroup$ @John Not true. People are large animals. $\endgroup$
    – Michael Vehrs
    Jun 1 '17 at 6:50
  • $\begingroup$ @MichaelVehrs, as awful as it sounds, that might be the best choice. I don't know if fish/animal skin would tan into a strong enough leather for use in boats. Even human skin would be pretty thin. $\endgroup$
    – ShadoCat
    Jun 6 '17 at 18:22
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I think the most likely answer would take the form of the reed boat similar to the ones used in Egypt for a time and by just a new design to make sturdier hulls by changing up weaving process. Of course this could also be done with different types of grass or maybe even crops grown and selected for that purpose.

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  • $\begingroup$ I was thinking of this but I don't think that the grass on that island is strong enough for this. It might work as a short term desperation play until they got skins that were big and strong enough to use. $\endgroup$
    – ShadoCat
    Jun 6 '17 at 18:20
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Boats are either built using wood or metal, at least for their chassis/frame.

If we rule out wood, since the island lacks trees, we are bound to use metal. But smelting and forging metal requires heat, which in turn requires wood or coal.

However, since the buoyancy is given by the volume of displaced water, they could have figured out a way of optimizing the wood usage, like building a frame with wood and use some other material to shape the shell. In this way with the same amount of chopped trees more boats could be built. If this was done before they chopped off the last tree, it could have helped them in better managing the local resources.

Another option could have been importing bamboo like plants, which could have been used to build ships like the Egiptians did (they also had no trees in the desert, but managed to navigate).

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  • $\begingroup$ This occurs after they “ran out” of trees. I suppose there are still woody plants, but no large trunks. $\endgroup$
    – JDługosz
    May 31 '17 at 5:30
  • $\begingroup$ @JDługosz, see the edit. $\endgroup$
    – L.Dutch ♦
    May 31 '17 at 5:38
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    $\begingroup$ «Boats are either built using wood or metal.» not grass, skin, seashells, pumice, …? You dismiss all the creative answers I was hoping to see! What about taming the dolphins and using them as mounts, instead of eating them? $\endgroup$
    – JDługosz
    May 31 '17 at 7:25
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    $\begingroup$ Eskimos used boats made of something else, neither wood nor metal... See kayak: "these first kayaks were constructed from stitched seal or other animal skins stretched over a wood or whalebone-skeleton frame". $\endgroup$
    – AlexP
    May 31 '17 at 9:18
  • $\begingroup$ Points taken, answer edited $\endgroup$
    – L.Dutch ♦
    May 31 '17 at 9:46
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An alternate technology path for boat building that comes to my mind is the use of ceramic materials.

Limestone should be readily available on your island either as geological deposits or by directly harvesting coral. Using limestone or other mineral sources it shouldn't be to hard to construct a binder material to make a form of concrete. Limestone does have to be heated to make Portland cement, and lacking trees for fire this might present some difficulty, luckily most islands in the pacific, including Rapa Nui, are volcanic providing a potential supply of heat for baking lime.

Additionally the volcanic island contains very porous pumice deposits. Pumice rocks will in fact float on water possibly leading your innovator genius to develop them for boat building. When used as an aggregate in concrete, pumice makes the finished product much less dense, helpful when constructing a boat.

Since concretes rediscovery and refinement in the 1800s it has actually been used many time as a cheap material to construct barges and ships, specifically during World War 2, when faced with resource restrictions.

https://en.wikipedia.org/wiki/Concrete_ship

The larger concrete boats have been built using steel reinforcing which is not likely to be readily available on your lone island, but the American Society of Civil Engineers hosts a yearly college contest to build concrete canoes with minimal to no steel reinforcing material, proving that it is at least a possible technology path to pursue.

http://www.asce.org/event/2017/concrete-canoe/

concrete canoe

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  • $\begingroup$ Most pacific islands are volcanic mounds. They don't have much, if any limestone. $\endgroup$
    – ShadoCat
    Jun 6 '17 at 18:25
  • $\begingroup$ @ShadoCat Coral = Limestone. Many Pacific islands are covered in limestone deposits from old coral reefs lifted up by volcanic action, but if needed you could directly harvest limestone from a coral reef. $\endgroup$
    – Josh King
    Jun 6 '17 at 18:46
  • $\begingroup$ Limestone is generally compressed coral. I don't know if any of the coral in that are would be old enough to be compressed to the point that it was no longer porous. Also, as a lone island rather than a chain, I don't know if there had been any coral before the volcano formed the island. $\endgroup$
    – ShadoCat
    Jun 6 '17 at 19:00
  • $\begingroup$ This island in particular does not have a major reef system. That's why they need to fish deep-sea tuna rather than harvesting the shallow's life. $\endgroup$
    – JDługosz
    Jun 7 '17 at 4:16
  • $\begingroup$ Cooking limestone makes quicklime. Portland cement requires adding magnesium and other things. They would have to learn to add ash to the limestone to make a waterproof cement. Assuming any limestone existed there. $\endgroup$
    – JDługosz
    Jun 7 '17 at 4:23
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discovery of stone boats

From the Wikipedia section on geology: (emphasis mine)

[A]ll of the great images of Easter Island are carved from the light and porous tuff from Rano Raraku. … The Puna Pau crater contains an extremely porous pumice, from which was carved the Pukao "hats".

Presumably hats were not invented for the statues — people made regular hats for themselves, perhaps as sunshades. They will have noticed that an upside-down hat is like a bowl, our genius realizes the similarity in a concave shape with the dugout canoe.

They would also know, from living there and having lots of rock fragments from the quary industry, that some kinds of rock floats.

So, the stone hat becomes a prototype for a stone boat. The rock is not “closed cell” foam and becomes waterlogged after a while. So they would need to coat the surface or make a skin boat over a stone frame. The latter proves fruitful as they no longer need a solid bowl but meerly a frame.

The return of deep-sea fishing brings the resource of animal skins that they use in more advanced designs. Early fat/mud coatings helped them bootstrap the industry, at least supplimenting the remaining wood boats and taking on seconary roles thus freeing the old boats for deep hunting.

sea farming

There is no reef system, so not much life in the shallows. They did have some shellfish though.

Why not farm the sedentary shellfish? Modern farmers use dangling lines from a floating platform. If they figured out something like this, they could position them for prime feeding, move them in during bad weather, keep other animqls from preying on them … in fact, attracting other wildlife will become another resource rather than a pest! They are in fact starting an artificial reef! The open fields of shells are bait for the fisherman.

leads to calcium

Now this influx of shellfish has a second effect: shells. There’s no limestone or coral on the island, but shells can serve as the basis for making quicklime.

Having this cement will be useful in their technology and industry. But, it’s not waterproof. The Romans made concrete by discovering volcanic minerals including fly-ash. This is a volcanic island… without digging into the actual composition myself, let’s presume they could find something that, ground up and mixed with the shell, produced a somewhat-useful water-resistent cement upon cooking.

leads to iron?

The idea of cooking rocks leads to the discovery that their island is a rich source of iron ore.

The problem is, they need energy. Without coal, and without trees to make charcoal, their knowledge will exceed their industry at this point.

dirt farming

The nearby islets covered with birds and lush growth — unlike their ruined land — might lead them to discover guano as a source of nitrogen fertilizer. The idea of farming is already established, so they encourage the plants they want, tending them and getting yields greater than the wild.

By this point, they know they want resources for other technological uses, rather than just direct personal consumption. So they grow crops for feeding animals, for use as fuel and building material, etc.

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Well there was one tree left on Easter island.

A single native large tree did survive on Easter island it was however so hard to get to no had succeeded until modern equipment became available. Thor Heyerdahl collected seeds from the last remaining toromiro. A group of islanders could make a great endeavor to reclaims seeds from the one tree left on the island. There is one tree that was left on the island it is on the far side of a volcano on a tall rocky spire, that would have killed most of the people trying to get to it.

from that they would need a very strict form of tree farming and lumber control laws like the Japanese had. Of course they would also need to wipe out the invasive rats on the island, which are what prevented new seedlings in the first place and were a major contributing factor in the deforestation.

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  • $\begingroup$ That article ignores the archaeological evidence of warfare and canibalism. Recovering a tree population is not an answer. $\endgroup$
    – JDługosz
    May 31 '17 at 10:53
  • $\begingroup$ Sure it is, and it is the only way they will get seafaring back. They don't have the freshwater or plants to make reed boats, no large animals for leather, and you are not smelting metal without charcoal. Note the article is only talking about the trees not the society. $\endgroup$
    – John
    May 31 '17 at 18:57
  • $\begingroup$ The few reeds the have are small, unsuitable to make ture seafaring craft. To drive the point home they had reed boats, they just could not use them on the sea. $\endgroup$
    – John
    May 31 '17 at 19:13
  • $\begingroup$ I see part of the problem, I linked the wrong article, I fixed that. $\endgroup$
    – John
    May 31 '17 at 19:21

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