The 14th & Final!
So it has all come to an end after (three?) months of blogging (it seems
so much longer). Today will not only be my first post in 2017, but also a final conclusion to the blog bringing together all the
elements we have been discussing in the past 13 posts (and
hopefully finding some common themes)! I have enjoyed writing this blog, and have certainly learnt a
lot along the way, and I hope you have too! Today we won't be introducing any
new information, but rather this post will be committed to combing the previous
discussions of Quaternary extinction and migration that
have been covered since beginning in October.
So let’s get down to it!
What have we talked about in the past 13 posts?
Extinction
Causes has been a key theme during the progression of this blog series. Below are the main explanations we have discussed, as
well as the extent to which they are supported by academic literature:
The Overkill Hypothesis (Humans): Unlike in previous points in the ice ages, the late-Quaternary saw widespread extinctions.
Some scientists advocate that the development of anatomically modern humans, and their hunting techniques are to
blame. This hypothesis has good support.
Climate Change: Was climate
change to blame? Perhaps. In the past and into the future many researchers
advocate the leading role in climate change as a reason for species extinction. It has become
increasingly clear that all extinct (and
regionally extinct) species were effected to some extent by
changes in climate. Climate change undoubtedly played a role in extinction.
The Hyperdisease Hypothesis: This was one of the first posts. In North America, there is evidence for tuberculosis among populations of mastodon. Some have taken a
human-derived disease as the cause for mass extinctions. Although disease may have affected North American mastodon, there is NO evidence for this in Europe.
The Extraterrestrial Impact Hypothesis: Mineral and chemical evidence
from an ‘impact layer’ is used as the cause for extinction, including the onset of the Younger Dryas. This hypothesis has many holes, and has been largely
discredited.
Hopefully you can see from this that there are two key hypotheses in this discussion: humans and climate change.
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& just how did they affect fauna?
Species- proposed
total and regional (still extant) extinction
causes:
Woolly mammoth (Mammuthus
primigenius): climate and people (cold adapted tundra species).
Straight-tusked
elephant (Palaeoloxodon
antiquus): climate and environmental change (warm adapted).
Cave Lion
(Panthera spelaea): climate and
environmental change, possibly associated prey
loss.
Extant Arctic fox (Vulpes lagopus):
climate and environmental change (cold adapted).
Extant
Collared Lemming (Dicrostonyx
torquatus): climate and environmental change (cold adapted).
Extant African Hippopotamus (Hippopotamus
amphibious): climate and environmental change (warm adapted).
European Hippopotamus (Hippopotamus
antiquus): climate and environmental change (warm adapted).
Cave Bear (Ursus spelaeus):
climate and vegetation change (predominantly herbivorous).
Woolly rhinoceros (Coleodonta
antiquitatis): likely climate (cold adapted), humans may have played a
role.
Interglacial rhinoceros (Stephanorhinus
hemitoechus): climate and environmental change (warm adapted).
The dodo (Raphus cucullatus):
Humans!
Top left (cave bear: source),
bottom left (arctic fox: source), top right (dodo: source), bottom right (woollyrhinoceros: source).
& so we begin to answer those initial questions...
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What was here?
How, and when...
& Why isn’t it here now...?
Personally, I believe that
humans were not singularly responsible for the extinction of most of the fauna
that disappeared during the late-Quaternary.
Though, there is plenty of evidence
throughout the past that we have played a key role (see: penultimate post). I believe from the papers that I have reviewed
throughout this blog series, that it
has been a combination of climate-driven environmental change and (sometimes)
the contribution of human activity that has caused animals to become extinct. There are many cases where regional extinction of species (e.g. collared lemming: post 6) had nothing to do with human
activity, moreover it was large mammals
(e.g. woolly mammoth: post 2) that
faced the true consequences of early-human (or hominin) interaction. More research is necessary, and it is up to
you to form your own opinion. Still, I leave you with a statement from a now
aged but still very relevant paper by Anthony Stuart:
Stuart (1991) “Extinctions did not occur earlier in the Pleistocene because ‘anatomically
modern humans’ [us] with upper Palaeolithic hunting technologies were not present” (p. 550)
This may very well be true.
So that’s it, the 14th and final post. I hope that someone has found use from this, because I have certainly learnt a lot from writing it.
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