Afterthoughts

Having wrapped up my Easter Island research I feel there are a couple of things I should mention concerning the blog. My blog has largely focussed on alternative explanations to the mysteries of Easter Island as opposed to the conventional story, largely because I personally find it more believable (and interesting). I hope I have remained as objective as possible in presenting the research I've done and I hope you readers also kept an open mind when reading this blog and do so should you go on to do further research. It’s important to note that we do not fully know the story of Easter and continued research is almost always necessary with these sorts of things. Even with the alternative story there are many issues, to list all of them would be beyond the scope of this blog, but I hope I have shed some light or helped promote a new perspective on the long standing question of what exactly happened on the island. For more information on the conventional side of the story, as always, I recommend Diamond 2005, which regardless of which argument is correct provides a huge amount of important information on this topic, not just relating to Easter Island. 

As mentioned in my previous post, whichever story about Easter proves true, the tale of the island provides important lessons about not living beyond our environmental carrying capacity, not exploiting vulnerable environments and keeping careful about what species we introduce to fragile ecosystems. 

Lessons for the present and future?

Even though in my blog I have tended to favour the opposing argument to the conventional story, which obviously makes a very good analogy for the issues human society faces today in regards to environmental degradation and climate change, I still think that the alternative explanations offer important lessons. 

Vulnerability

A key issue talked about by a number of researchers was the vulnerability of the environment on Easter. The island received a very small amount of rainfall, relatively strong winds and a very small amount of volcanic dust to fertilise the soil (Rolett and Diamond 2004). Furthermore, the soils of the island allowed rainfall to percolate very quickly due to it’s volcanic nature, cutting down freshwater supplies significant, reflected by the island’s one stream (Flenley and Bahn 2003). The island therefore had poor soil quality and a small amount of reliable freshwater, making it almost predisposed to deforestation. Furthermore, the small size and isolation of the island made it relatively deficient in biota (Flenley 1993), giving it very low biodiversity, thus making it especially vulnerable to invasive species (Willis and Birks 2006). 

I think therefore Easter shows the danger of exerting pressure on already vulnerable environments. Hunt and Lipo (2009) showed evidence of adaption developed by the islanders, but the environment still declined regardless. In terms of biodiversity and conservation management this is a key lesson, as identifying areas most at risk of environmental degradation is a major objective (Willis and Birks 2006), and the treeless island, almost devoid of native species of both animals and plants should be a stark warning.

Invasive Species

As mentioned the geography of the island made it especially vulnerable to invasive species and as I mentioned in a number of posts rats were likely a key driver of deforestation on the island, gnawing palm nuts to prevent the forests from regenerating (Hunt & Lipo 2009). Rats as an invasive species on a small island would have been able to reproduce rapidly with no natural predators and prey on the animal and plant life on the island almost unhindered.

An article on Britannica discusses the impacts invasive species can have on ecosystems in depth, noting that they can both reduce an ecosystem’s biodiversity and cause severe economic harm to the people dependent on the ecosystem’s biological resources, as rats would have on Easter, through their use of both palm nuts and animal eggs as primary food sources (Hunt &Lipo 2009). It is possible that rats not only aided in depletion of the forests but through their predation of other animal species made further resources more scarce for the islanders, pushing the Polynesians into pressuring the forests and the land to make up for this. The effect invasive species can have on ecosystems can be devastating as I have discussed in earlier posts, and indeed likely had a very harmful impact on Easter, so it is important (as conservationists have noted) to take heed of the effect invaders can have on environments, especially fragile ones like Easter's.  

So the alternative Easter Island story does provide some clear lessons for the issues humanity faces today, with environmental vulnerability and invasive species being key topics in most serious conservation and biodiversity management schemes.

Concluding thoughts Part 2 - The Society

So now I will summarize my thoughts about what it was that pushed the society into complete demographic collapse. As I have argued in my blog, I don’t find the ecocide argument that convincing and have instead looked for other alternatives, most notably the argument that European contact was what really caused the population to rapidly decline.

The argument that places the degradation of the environment on Easter as the cause for the collapse of the society ‘ecocide’ argues that the islanders were dependent on the forests for numerous resources, not only for food but also the wood provided material for canoes used to fish, ropes and logs to transport the great stone statues and so on (Diamond 2005). Therefore once the forests became scarce the islanders ran out of resources and Easter exceeded it’s carrying capacity, causing the society to pushed into famine, internal strife and civil war, ultimately resulting in collapse.

 As mentioned previously Hunt & Lipo’s (2009) paper observes that the only sharpest and sustained population decline on the island occurs long after the greatest period of deforestation, but more notably directly after European contact, where it very sharply drops. This gap of several hundred years between deforestation and demographic collapse made the ecocide argument unconvincing for me on its own, but also important was, as I mentioned in ‘Part 1’, the fact that the islanders showed the ability to adapt to their degrading environment.

I therefore looked to the other major argument, that European contact was the cause for the collapse of the society on Easter. The main evidence for this I suggest is Hunt & Lipo’s (2009) observation about the only sustained population decline occurring after European contact. Indeed, this is something you would expect, with the well documented effect of Old World diseases wiping out New World populations upon contact. Furthermore, the main evidence used by other writers to display periods of warfare (obsidian points) appears to actually become most common after European contact in the 18^th century.

Additionally, Bahn (1997) documents frequent visits in the 18^th and 19^th century by Europeans on the island, a number of which involving abduction and murder (also to note is that a great amount of raids would have gone undocumented). Bahn (1997) estimated that around 1000 to 1400 natives were deported by slave raiders between 1862 and 1863, which would have been devastating to such a small island.

Finally, one key piece of evidence used to describe civil warfare that tore the island apart following the deterioration of the forests are oral traditions, are notoriously unreliable (Rainbird 2002), being transcribed by European missionaries who would likely want to portray the islanders as savages needing the Europeans to save them and turn them to civilization (and Christianity). Additionally, despite the dearth of oral traditions describing conflict placed before European contact, there are almost none that describe the traumatic experiences the islanders faced after contact, involving repeated slave raids, killings and other such atrocities (Rainbird 2002), again making the issue of bias clear.

I therefore find the argument that European contact was the cause of population collapse a more compelling one, mostly due to the observation that evidence for warfare is most prolific at this point and that the society on Easter increases in size right up to European contact and then very sharply declines. Furthermore, the other main source of evidence for warfare, oral traditions, are very dubious sources of information with the question of bias being significant, making the counter argument a relatively weak one.

Concluding thoughts Part 1 - The Forests

Firstly I'd like to say sorry for a long gap between this and my last post but you know what it's like going back to the family home at Christmas! Anyway, back to Easter Island! In this and my next post I will be concluding my thoughts about the mysteries of Easter Island; what caused the forests to deteriorate and what caused the population to collapse? In this post I will be looking at the forests. The conventional story argues that the islanders put too much pressure on the forest, both for food resources and for wood for canoes and the statue building. Other writers argue the importance of climate change while others put further alternatives to blame, such as rats and so on.

Rollet and Diamond (2004) argue that the key issue facing the island was that the geography of Easter was extremely vulnerable, to an extent that it was predisposed to deforestation. Receiving some of the lowest amounts of volcanic dust and tephra than any other Pacific islands meant poor soil quality and receiving a relatively small amount of rainfall but reasonably strong winds compounded this. The island was therefore very fragile, and the presence of some thousands of Polynesians that were dependent on the land for most resources would have put enormous pressure on the environment.

Hunt & Lipo’s (2009) paper observed that the greatest period of deforestation (around 1200AD) occurs several hundred years before the only sustained population decline on the island that occurs after European contact, suggesting that the islanders were not the sole driver of deforestation as they were not solely dependent on the forest for all their resources. As Hunt & Lipo (2009) add, the islanders developed numerous adaptations to the poor geography of the island to cope with resources scarcity, suggesting that they did not just thoughtlessly put up with an increasingly degraded environment. Furthermore, as I discovered in this post, the islanders may not have even used trees that heavily for statue building and transportation, which is a key source of blame in the conventional argument. 

This conclusion therefore led me to look at the role climate could have played in deforestation. One of the first things I noted while researching this was Hunt’s (2007) observation that Easter’s forests survived thousands of years of climatic changes since the Pleistocene, suggesting that it is unlikely climate could be solely to blame. Junk and Claussen (2011) developed climatic models to observe the influences El Nino Southern Oscillation could have had on Easter’s vegetation, as well as the impact of volcanic eruptions, the Medieval warming period, the ‘Little Ice Age’ and a number of other climatic variations. They concluded that no significant or even marginal changes in vegetation or forest cover was observed as a result of climatic variations between 800 and 1750AD on Easter. Although they add that is possible small scale changes in climate could have been important, such as localised droughts, a crucial issue is that there is no direct information about climate change on Easter (Mann et  al.2008).

Since it seemed that it wasn’t just the islanders that pushed the environment to the limit, and that climate was also not to blame, I looked for alternative explanations. One argument is that rat populations on the island would have been able to grow on the island without predation (small island with low biodiversity and lack of predators (Diamond 2005)), putting enormous pressure on forests as they are able to prevent them regenerating through their use of tree nuts as a primary food source (Hunt 2007). Hunt (2007) noted that as the forest declined, so did rat populations, making this an interesting argument. Andreas and Bork (2010) noted several issues with this argument, an important one being widespread evidence of felled and burnt trees across the island, suggesting that both rats and humans played relative roles of important. I therefore conclude that it is likely the combination of human and rat pressures on the forests in an already fragile environment was the main cause for deforestation, with localized droughts probably also playing a role.

Europeans - is there anything we haven't ruined?

As I have discussed, the traditional Easter Island story has been criticized for numerous flaws, notably by Hunt & Lipo (2009), on the argument for ecocide as the cause of societal collapse. One issue is the disconnect between deforestation on the island and the population collapse, as I mentioned in an earlier post these two events occur between 100-300 years apart (Hunt & Lipo 2009). This therefore leads me to question whether it was environmental degradation that pushed the society to the edge. Many writers instead argue that contact with Europeans was the cause for the demographic collapse on the island, the fact that first contact with Europeans occurs around the time the sustained population decline instantly makes this an interesting argument (First European visitor - AD1722, Population fall - AD1750 [Hunt & Lipo 2009]).

The ecocide argument, as Rainbird (2002) comments, rests mostly on the connection between environmental degradation and the ensuing collapse. But the evidence suggesting that these two are causally related appears questionable. Diamond (2005) uses the discovery of obsidian points in archaeological finds as evidence for periods of increased fighting, but Bahn and Flenley (1992) point out that these points become most common in the 18th and 19th centuries, where they become the most common artifact on the island, suggesting conflict occurred then, not centuries beforehand. Another source of archaeological evidence are bone pathologies from human skeletons, but as Rainbird (2002) writes, most skeletal injuries observed appear non-lethal, with no evidence of widespread civil war before European contact. Additionally, Hunt & Lipo (2009) note that the islanders developed coping strategies such as stone mulching to optimize crop cultivation in the increasingly nutrient-poor soils and variable rainfall conditions of Easter, suggesting that environmental degradation didn't just push the island into infighting. Furthermore, Hunt & Lipo's (2009) research also suggest population increased during the worst period of deforestation.

Obsidian axes similar to those found on Easter

Another important source of evidence for the ecocide argument is oral traditions of the islanders, which describe periods of social upheaval and conflict. Peiser (2005) notes, that it is generally agreed the oral traditions of Easter are untrustworthy, contradictory and historically unreliable, as well as being relatively late in origin. Rainbird (2002) raises a very interesting point, that there are a dearth of traditions attributed to pre-European contact, but none that describe the numerous violent confrontations with European invaders  during the first half of the 19th century, which considering the fact that oral traditions where transcribed largely by European missionaries makes the question of bias a very important issue. Rainbird (2002) suggests that it is likely in an attempts to display the islanders as savages and Europeans as bringing civilization to them, the missionaries in a way edited the oral traditions to date the times of conflict before European contact.

Bahn (1997) writes that between 1722-1862, some 53 recorded vessels visited the island, with a number of these visits involving abduction and murder. For example, a common practice was for whale ships to abduct islanders to replace crew that had died during the voyage (Bahn 1997), and it is widely agreed that slavers repeatedly raided the island. Bahn (1997) suggests that mass deportations and raids led to the social order of the island collapsing, with whoever was left behind fighting over what little resources the Europeans had not taken. It is possible, Bahn adds, that the oral traditions that depict internal violence reference these periods, not events many hundreds of years earlier, which seems plausible considering how young many of the oral traditions are (Peiser 2005). Bahn (1997) adds, that an estimated 1000-1400 natives were deported by slave raiders between late 1862 and early 1863. As population estimates range from 3000 to as high as 20000 (Flenley and Bahn 2003), this would be devastating (especially if numbers were near the lower range, which Hunt & Lipo's research suggest they were).

The debate over whether it was European contact that caused the population collapse is therefore a compelling one, especially considering the proximity of both these events, as well as separation between the collapse and the environmental degradation. The main archaeological evidence of conflict (obsidian points) suggests that most conflict occurred after European contact. The evidence to suggest the conflicts occurred in the island's prehistory appear relatively unreliable, mostly being based on oral traditions (Peiser 2005). Finally, the islander's adapted to their changing environment, and population actually appears to increase despite deforestation (Hunt & Lipo 2009). As we know so little about this time period it is difficult to categorically state that the collapse was caused by European contact, but the similar timings, the ability of European contact to cause demographic collapse (Hunt & Lipo 2009) and the lack of evidence to suggest otherwise seems to indicate it is a plausible argument.

Unraveling the Mystery of Easter Island

So my last post was about rats and the role they may have played in deforestation on Easter Island. As you may have noticed, a great deal of the rat debate comes from the archaeologists Terry Hunt and Carl Lipo, (who I think I take far too much information from!). Upon searching the news for stories related to Easter Island I came across this blog entry on the courier-journal.com, reviewing one of Hunt and Lipo's latest books "The Statues that Walked: Unraveling the Mystery of Easter Island," written in 2011. As Peter Smith at the courier-journal reviews, the book goes into great detail looking at the entire Easter Island story, reviewing (and rejecting) evidence for the traditional explanation (ecocide) and instead suggesting that rats drove deforestation the island and that contact with Europeans led to the island's ultimate collapse.

Mr. Smith makes a closing point which I think is very important: assuming ecocide was not the cause for the collapse on Easter, the alternative story still offers lessons: "Live within your means. Watch out for invasive species. And especially invasive people," (Courier-journal.com 2012). The impact invasive species can have on ecosystems, as I have discussed, can be potentially catastrophic, so if we can't learn a lesson about human driven environmental degradation from Easter, we can certainly be more cautious about this one. Especially as humans have time and time again ruined the biodiversity of numerous ecosystems by introducing outside species into them - e.g. introduction of the Nile Perch into Lake Victoria in 1955 devastated native fish populations. Anyway, I highly recommend both Hunt and Lipo's book and the courier-journal.com, which seems to offer news and posts related to almost anything I can think of let alone Easter Island! 

A rat race?

As my earlier posts have discussed it is likely that deforestation was driven by a number of factors. I touched upon the role that rats may have played in this post but now I will go into a bit more detail about them. Hunt and Lipo (2009) write that there is an extensive literature documenting the profound impact rats have had on the vegetation and ecosystems of a number of islands across the Pacific. Although, Diamond pointed out (2005) that while on some islands rats have had catastrophic effects, on others they have made no apparent impact, showing that although there is potential for rats to be damaging to island ecosystems they aren’t necessarily the cause in every case. 

Andreas and Bork write (2010) that it was common for Polynesian settlers to bring rats with them to an island as a valuable source of protein, and indeed on Easter numerous rat bones were found in archaeological excavations and often in cooking pits. Rat bones on the island have been dated to first appear as back as between 600AD and 1260AD (Andreas &Bork 2010), showing that they were around long enough ago to potentially have played a role in the greatest period of deforestation between 1200AD and 1650AD (Hunt & Lipo 2009).

If you remember from one of my previous posts, the island had a particularly fragile environment, especially to invasive species due to the relatively small biodiversity and lack of predators (Hunt 2007). Rat populations therefore could have grown very rapidly on the island, and as palm nuts were a primary food source (Sardar 2008) it is likely they would have had some sort of destructive impact on the forests, as was seen on numerous Hawaiian islands (Hunt 2007).

Hunt (2007:496) Shows decline of rat population between early and late period – rat populations dependent on forest resources?

However, as Hunt (2007) comments, the relative contribution of rats to deforestation remains poorly understood, although a large amount of palm nuts have been discovered gnawed. Andreas and Bork (2010) add that numerous pieces of evidence suggest that rats were not responsible for deforestation. Firstly, rats are unable to kill mature trees, making palms fully grown by the 13^th to the 15^th century able to survive till the first European contact due to their relatively long lifetime, suggesting a number would have indeed been cut down. Furthermore, numerous palm stump relicts have been found, as well as widespread ash and carbon layers to show that fires had burned over extensive areas of the island (Andreas & Bork2010).

Despite this, I believe writers like Hunt & Lipo are more suggesting that rats played a role of relative importance, rather than an all or nothing factor. Although it seems unlikely rats could have been the sole cause for deforestation, the evidence suggests that they must have played a significant part. Rat populations could have grown almost completely unhindered on the island and as palm nuts were their primary resource, it is likely this growth would have been reflected by forest destruction. Indeed, the greatest period of deforestation appears to occur following the growth of rats on the island and as the forests declined so did rat populations.