Easter Island – was it really so isolated?

(see also ‘No South American DNA in ancient Easter Island – and…?‘)

The fate of prehistoric Easter Island was an environmental catastrophe… but was it really, as Jared Diamond argues, in isolation? Perhaps Easter Islanders were trading both with other Pacific islands and with South America.

In Jared Diamond’s bestseller, Collapse, Prof. Diamond outlined various examples of environmental over-exploitation, including Viking Greenland, the Maya of central America and modern Rwanda. But his first example, Easter Island (aka Rapanui), was his ace.

The collapse of Easter Island

Easter Island is less than 15 miles long and is sited in one of the most isolated parts of the Pacific, lying 1300 miles east of the nearest inhabited island, Pitcairn, and 2300 miles west of the coast of South America.

Jared Diamond used the work of John Flenley and Paul Bahn to argue that Easter Island is a microcosmic metaphor for our modern world. Isolated from all other human life, it typifies what humans can do to destroy themselves when their resources are limited and over-exploited. We, like the Easter Islanders of prehistory, are bound for disaster unless we can only think ahead.

From the evidence that Diamond could gather he told the following story:

Easter Island was first inhabited around 900AD or a little earlier. The population gradually expanded then ballooned. Every inch of the island was farmed, the trees were all felled and the wildlife eaten. The population during this time may well have exceeded 15,000. This was probably the time when Easter Islanders erected their famed statues, the ‘moai’.

But soil erosion and depletion lead to decline. By the seventeenth century Easter Island was in a permanent state of warfare. When the first recorded European account of Easter Island was made in 1722 the population was reduced to perhaps 2000 people.

Diamond’s and rats’

Overall I don’t really have a problem with Diamond’s main story. Easter Island is clearly a wreck, it’s devastation probably caused by the arrival of people. But there have been some significant disagreements, particularly between Terry Hunt and Carl Lipo on the one hand, and the original researchers, Flenley and Bahn, on the other.

Hunt and Lipo firstly suggest that Easter island was not colonised until perhaps as late as the 13th century AD. While this has caused much argument between them and Bahn and Flenley, I suspect that Prof. Diamond wouldn’t be too concerned. For him this would only highlight the scale of the human disaster.

Hunt and Lipo also argue that imported rats were the main culprits for deforestation, preventing the regrowth of trees. Again, who brought the rats?

Perhaps the biggest criticism by Hunt and Lipo is that they say there is insufficient evidence for a population explosion of the proportions Bahn, Flenley and Diamond argue for. They estimate that population numbers were never much higher than about 3000 people.

The problem with either argument is that it’s difficult to prove what size of population existed before recorded history. So much devastation was wrought on the island’s population after the arrival of Europeans that it dwindled to almost nothing, making genetic studies difficult.

Sweet potatoes

To me a much more important issue is just how isolated Easter Island was during this time. Jared Diamond justifiably points out that there is no evidence of trade to or from the island. As an island it appears to have been entirely self-sufficient in food and tools (albeit stone ones).

However, there is one sentence in Diamond’s book that is worth quoting. “Easter’s crops were bananas, taro, sweet potato, sugarcane, and paper mulberry, typical Polynesian crops mostly of Southeast Asian origin.” Note the ‘mostly’. The one exception, the sweet potato, comes from the Americas.

Links to South America

The sweet potato, a tropical tuber (Ipomoea batatas), is thought to originate somewhere in Mesoamerica, probably southern Mexico. It was first cultivated there around or before 3000BC. By the first millennium its cultivation had spread east, around the Caribbean, and south, down the western spine of South America into Peru and Chile (see map)

The domestic form of the sweet potato cannot be grown from seed and has to be propagated by tuber cuttings (a bit like a some commercial varieties of normal potato). It also gets killed by seawater. Yet it is grown widely across the tropical and sub-tropical Polynesian islands of the Pacific and appears to have been grown there since pre-Columbian times.

Perhaps most revealing is the sweet potato’s name, generally variants on the word ‘kumara‘ in Polynesian dialects (including Easter Island’s)%. If it had been brought by Spanish or other European sailors it would have had names reflecting that European origin, such as ‘batata‘, ‘kamote‘ or some such. However, the name is remarkably similar to a Quechua (Peruvian) name for the sweet potato, ‘k^humara‘.

Easter Island not isolated

Generally speaking, people such as Jared Diamond talk of the colonisation of Easter Island as a one off event, followed by isolation. Colonists took seventeen days to get there from Pitcairn (say) and thought ‘Well, that’s me done travelling.” No one else then followed them. Well perhaps this was so but…

Easter island is the most easterly of the Polynesian islands. Although just under 2300 miles from Chile (and just over 2300 miles to Peru) there is no Polynesian island nearer to either South America or, in fact, the Americas.

It is, admittedly, marginal. Hawaii, to the north, is slightly further away (2400 miles), its near point the California coast of North America. However, while Hawaiians may or may not have reached California in Pre-Columbian times, the prehistoric natives of the California coast, as far as anyone can tell, never grew sweet potatoes.

Evidence presented by Henri Dumont and others also argues for an influx of pollen from other South American plant species into Easter Island, perhaps between the 14th and 16th centuries. This indicates some sort of South American connection.

To me the evidence of the sweet potato and the pollen is almost unequivocal (that’s the best I’m ever prepared to say). Easter island may not be ideally located for importing the sweet potato into the Polynesian world but there’s pretty much no other choice.+ However minor, Easter Island had some form of contact with South America.

But equally importantly, if Easter Island was the first Polynesian island to get the sweet potato then its spread throughout the Polynesian islands indicates some form of contact through Easter Island back to the rest of the Polynesian islands.

Following this logic, Easter Island was not isolated. In fact it may have been a bottleneck or pinchpoint on the only route between the Pacific Islands and South America. All boat traffic would end up stopping at Easter Island.

Not Thor Heyerdahl

If there were any connection between South America and Easter Island it would probably have been with the coast of Peru or Chile. The linguistic evidence suggests Peru.

The period of contact would perhaps have been from 900 or 1200 AD, when the Polynesians first arrived, and the fifteenth or sixteenth centuries, when the Spanish took control of Peru. According to Jo Anne Van Tillburg, radiocarbon dates suggest a florescence of culture in Easter island between the mid 14th century and the beginning of the 16th century (added 3/8/11).

In the north of Peru the Moche culture  had given way to the Sicàn state and Chimú ’empire’ by this time. These in turn lasted until around 1470AD when the coast was absorbed into the Inca empire. This fell to the Spanish around the 1530s.

I am not proposing the colonisation and diffusion of civilisation to Easter Island from South America. Nor am I proposing the opposite. Yes, there are similarities between the extended ears of Easter Island statues and Chimú and Sicàn gold masks from Peru but this is arguably a coincidence.

Furthermore the (admittedly limited) DNA evidence indicates that prehistoric Easter island never experienced a great influx of South Americans, even if there was an influx of South American pollen around the 14th century. So whatever the connection between Easter and South America, it could never have been huge.

So what am I arguing for?

The unlikely voyage of Tupa Inka Yupanki

There is an Inca legend, luckily recorded in 1572 by a Spanish explorer of South America, Pedro Sarmiento de Gamboa. It tells of the great Inca leader Tupa Inka Yupanki who was fascinated by the merchant sailors arriving on the Peruvian coast, bringing gold from islands out in the western sea.

So Tupa Inka sailed west, supposedly around 1480, with a great fleet of balsas to the islands of Avachumbi and Ninachumbi. He was gone almost a year, but when he returned he brought back ‘black’ people, gold, a brass chair and bits of a horse.

Most of this story is likely to be nonsense. The items listed were unavailable on the Pacific islands. Indeed, Tupa Inka would have had to sail to the other side of the world to collect any of these items.

However, the story may be a folk memory of distant islands to the west and of merchant sailors coming from those islands. Was this a genuine memory of an earlier time? Was it instead something arising from a desire for the indigenous people to have a sailing history equal in magnitude to that of the Spanish? Who knows.

Light trade?

This is where I push the data too far and potentially fall flat on my face. What if there were once Polynesian merchants bringing something highly prized to the shores of Peru from the Pacific Islands?

Well, as already stated, there’s no evidence for Easter Island trade, either between South America or the other Polynesian islands. Easter island was largely self sufficient in tools. There are, of course, good reasons for that lack of trade. It would have been unlikely that anybody would have bothered to carry stone tools or pots such vast distances either to or from Easter Island because they are heavy and you could make them yourself.

But I have one chance. What if the trade was in something really light and easily transportable but something that, given time, would rot away, leaving no evidence. Something really light… as light, indeed, as a feather.

Luxury feathers

One of the major trade items of both Mesoamerica and South America was feathers – red feathers, green feathers, irridescent feathers of all kinds. Just think native American headdress. Some were just valued, others were as prized as gold, if not more so. Feathers could be a high status item, a king’s trade good.

Feathers were also highly valued in Polynesian society. The red feathers of, for example, the Scarlett Honeyeater, were a significant form of currency in Santa Cruz and neighbouring islands. Jared Diamond himself points out the significance to Polynesians of feathers twice in Collapse, making the often argued point that the red scoria discs (pukao) on the top of some Easter Island statues probably represented red feather headdresses.

David Steadman has stated that something like twenty percent of all Pacific bird species went extinct in the period between the Polynesian colonists arrival and the subsequent arrival of European ships. This effect may well have been due to the predations of rats on bird eggs.* However, David Houson suggests that a significant part of this may have been due to the feather trade.

In this light the example of Henderson Island, discussed by Jared Diamond in Collapse, is intriguing. As Diamond points out, Henderson Island is difficult to live on. It has almost no fresh water and the ground is uplifted coral, almost impossible to farm.

Yet in pre-Colombian times it contained a small resident population of people who eked out a living there, even managing to import high quality tools from other, relatively nearby islands. The island’s middens are dominated by masses of bird bones. Were bird feathers an exported trade item? Were they in fact the main reason why people lived on the island at all?

Is there just the remotest possibility that these two societies, those of South America and of the Pacific Islands, somehow met and traded in such things as feathers?

The collapse of civilisation

Diamond argues for the collapse of societies on the Polynesian Islands of Henderson and Pitcairn around 1450 AD or a little later. He also argues for the collapse of Easter Island society around 1600AD. Jo Anne Van Tillburg argues for a peak around 1500 AD with a collapse sometime shortly after (added 3/8/11).

For comparison, the collapse of Inca civilisation in South America followed the arrival of the Spanish in the Americas. The Spanish invaded the Inca heartland in 1532 AD and the final phase of Inca control dates to around 1538 AD. However, smallpox was probably already hitting the west coast of South America by this time. So overall the collapse occurred during the first half of the sixteenth century.

Is there a link between these events? Could the collapse of Inca civilisation have, in some way, caused the collapse of the Easter, Henderson and Pitcairn societies?

If there was pre-Colombian trade between Easter and South America then the arrival of the Spanish provides a convenient point for it to stop. The new economic conditions in the mid sixteenth century could have been enough on their own. Alternatively, smallpox or some other infection could have caused trade to cease.^

Environmentally sound?

I have no idea whether the case I’ve put forward above is reasonable. Whatever,  I’m sure that the destruction of natural habitats like Easter Island’s really did have a major effect on the people who lived there. I think it ultimately left them isolated.

But in fact pretty much everything that people the world over have done since they started trading and farming has had negative environmental consequences. Every field opened up is a reduction in biodiversity. Every precious item collected involved digging holes in the ground or the pointless killing of animals and plants.

Yet people everywhere, not just on on Pacific islands, have achieved something amazing since the start of the Neolithic Revolution. They’ve managed to wreak all this damage but somehow manipulate the odds so far in their favour that there are more of them now than ever before.

So what impresses me, as it does all of civilisation, is not that people wrecked Easter Island. It’s that they, like us, have managed to survive what they’ve done.

Notes

% The following are words for sweet potato – In Peru – cumara, kumar, kumal; In Ecuador, kumara, cumar’, umar’; In
Colombia – umala, kuala;  On Easter Island and New Zealand – kumara, On the Marquesas – kuma’a; On Aitutaki – ku’ara; On Tahiti – umara; On Tonga and Fiji – kumala. (from here)

+Some people have suggested a direct route from the Marquesas or Societies Islands to South America. To me this view seems surprising as the distance to be travelled would then be at least 3800 miles.

* The volcanic Galapagos Islands have been lucky. All the evidence suggests the occasional rare visit from South Americans in Pre-Columbian times. However, there is no evidence of the presence of Polynesians, or their rats. This is why the island is such an important nature reserve.

^It would have been possible to transmit smallpox to Easter Island by boat from South America at this time. However, the epidemic of the 1860s perhaps suggests that the population hadn’t developed immunity to it so maybe they’d never experienced it before.

References

Adelaar, W.F.H. 1998 The name of the sweet potato: a case of pre-conquest contact between South America and the Pacific.  In: Janse, M. et al. Productivity and creativity: studies in general and descriptive linguistics in honor of E.M. Uhlenbeck, Mouton de Gruyter. p403-412.

Brander, J. A. & Taylor, S. M. 1988 The Simple Economics of Easter Island: A Ricardo-Malthus Model of Renewable Resource Use, The American Economic Review 88, p119-138.

Dumont, H. J. et al. 1998 The end of moai quarrying and its effect on Lake Rano Raraku, Easter Island, Journal of Paleolimnology 20, p409-422.

(This paper suggests the arrival of South American pollen in Easter Island around second half of 14th century. It also argues that Moai quarrying stopped at the same time. It suggests Pre-Columban trade links between the Incas and Easter Island.)

Gibson, A.C. Economic Botany – Sweet Potato page

Haemig, P.D. 1978 Aztec Emperor Auitzotl and the Great-Tailed Grackle, Biotropica 10, p11-17.

Houston, D.C. 2010 The Impact of Feather Currency on the Population of the Scarlet Honeyeater on Santa Cruz. In: Tideman, S. & Gosler, A. Ethno-Ornithology, Birds, Indigenous Peoples, Culture and Society, p 55-66.

Hunt, T. L. 2006 Rethinking the Fall of Easter Island, American Scientist 94, p412.

Hunt, T.L. & Lipo, C.P. 2006 Late Colonisation of Easter Island, Science 311, p1603-1606.

Hunt, T.L. & Lipo, C.P. 2007 Chronology, deforestation, and “collapse:” Evidence vs. faith in Rapa Nui prehistory. RapaNui Journal, 21, p85-97.

Markham, C. 1907 Translation of Pedro Sarmiento de Gamboa’s History of the Incas.

Steadman, D.W. 1995. Prehistoric Extinctions of Pacific Island Birds: Biodiversity Meets Zooarchaeology, Science 267, p1123-1131.

Photos from Sheep”R”us‘ photostream, Britannica Online Encylopedia,

Additional References

Gunn, B.F., Baudouin, L. & Olsen, K.M. 2011 Independent Origins of Cultivated Coconut (Cocos nucifera L.) in the Old World Tropics, PLoS One (online)

Another additional argument, pointing out that coconuts were probably taken to northwestern South America by Polynesians in Pre-Colombian times. The dates they suggest, around 200-300BC, are perhaps a little early, but…

Roullier, C. et al. 2012 Historical collections reveal patterns of diffusion of sweet potato in Oceania obscured by modern plant movements and recombination, PNAS110, p2205–2210.

Article making a strong genetic case for westward trade in the sweet potato from Peru or Ecuador back through Polynesia during the period from 1000 AD onward. In fact it’s enough to make my entire article pointless, as this is much better and really invalidates Jared Diamond’s argument.

Van Tillburg, J. A. 2011 The Easter Island Statue Project, University of Pennsylvania Podcast, Itunes U (see also EISP website)

Gives approximate dates for statue development and also discusses the structure of society during their building.

Wilmshurst, J.M. et al. 2011 High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia, PNAS 108, p1815-1820.

Storey, A. et al. 2007 Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile, PNAS, 104, p10335–10339.