Generally speaking there has been a move away from the
original ecocide theory. As more and more is learnt about past climate changes,
how these changes relate to vegetation and society, more complex theories
develop.
Firstly I just want to draw your attention to the importance of
proxies in enhancing our understanding of past events. Rull et al 2013 (and an
updated 2014 version) explore evidence showing that human presence on Easter
Island was quite probably 1500 years earlier than previously thought. The introduction
of new plants and increases in charcoal at around 450 AD suggest human
populations reached the island long before we previously thought.
The Moai at night. Source: National Geographic
Rull et al demonstrate this in their meta-study, which looks
at emerging evidence supporting the move away from a simple ecocide hypothesis.
The Ecocide theory dismisses any causational factor that isn’t human activity
and implies that the change from palm forests to open grassland (which
dominates Easter Island today) was abrupt and sudden.
However paleoecological and archaeological evidence suggests
the island actually underwent a more gradual change, spanning over 2000 years. In
addition, results from the authors’ previous studies show no empirical evidence
of any abrupt changes. Diatom assemblage changes and sediment from Lake Raraku
(Easter Island) illustrate a very slow change towards slightly wetter
conditions. With the onset of wetter climates, an increase in palm demise was
found and an increase in charcoal, used as a proxy for fire.
Lake Raraku, Easter Island. Source: Flikr
Rull et al’s argument is that with greater water
availability due to a wetter climate, populations on Easter Island would have been
encouraged to increase agricultural land. This increasing demand, driven by a
growing population in a more favourable climate, increased the use of resources
and need for cultivable land. Rull et al do accept that currently this theory
is highly hypothetical and more archaeological evidence is needed to increase
its standing. However this is a very logical argument and follows observed
trends in most human population growth.
Rull et al conclude that the history of Easter Island and
therefore our understanding of what happened there needs rethinking and
suggests a total revision may be necessary. I agree with this conclusion because
too often an over-simplified explanation is accepted as fact. As the
capabilities of looking at past climate and vegetation changes improves with paleolimnology
and paleoclimatology we should revisit these cases of civilization collapse. I
think we could probably learn a lot and may realise that more credit should be
given to these ancient societies. Rull et al points out that new theories are always
emerging, two most recent ideas focussing on climate changes relating to the
Little Ice Age and ENSO. These may become more prominent hypotheses if
evidence to support them is found.
Until next time!
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