Humans And Fauna In Australia Essay, Research Paper
In 1830 Mr. Rankin tied a rope around a projection out of a rock face in order
to lower himself into Wellington Cave (Horton, 1980). The projection turned out
to be the bone of a giant extinct marsupial. It was to be the first discovery of
a great range of giant marsupials. Were these animals extinct?? Horton (1980),
describes how Leichhart believed that on his journeys to northern Australia he
would find Diprotodon still roaming over the land. We now know that he was
probably only about 20,000 years to late (Flood, 1995). In general, all the
animals greater than 40 kg in body weight became extinct at the end of the last
Ice Age. By the mid 19th century scientists had already begun to postulate about
the disappearance of these animals, and today it remains one of the most
controversial subjects presented to man, (Horton, 1980). Australia was not the
only country to experience extinctions of large animals, (Martin, 1984). At the
end of the last glacial period nearly every continent experienced extinctions of
large animals. Animals like the Mammoth, giant ground sloths, and mastodons were
roaming the Americas. Northern Eurasia featured woolly mammoths, giant deer,
hippopotamus and straight tusked elephants. Of all the continents, it could be
argued that Australia lost some of the most distinctly unique fauna in the
world. The popular opinion for the cause of extinction is the ‘blitzkrieg’
hypothesis, which is held by such researches as Paul Martin in his controversial
article "Prehistoric Overkill: The Global Model". This states that
humans are directly responsible for these extinctions world wide. The Problem
with this model for Australia is that humans may have arrived on this continent
well before the extinctions took place (Flood, 1995). On other continents the
extinctions coincided almost exactly with the arrival of man (Martin, 1984).
European man was not the first member of the genus Homo to set foot on the
Australian continent. There is evidence to suggest that Aboriginal people have
been walking on Australian soil for many tens of thousands of years (Flood,
1995). Whether or not Aboriginal people interacted with the large now extinct
beasts is hard to determine. Did an overlap in time exist between humans and
these large beasts? Is there any evidence that humans actively hunted them, and
if they did, is it possible that they drove them to extinction? Land of the
Giants During the late Pleistocene, the last glacial period spanning roughly
100,000 years, the faunas were completely different to those that are
represented today. The most pronounced difference is body size. The term ‘megafauna’,
meaning ‘large animals’ has been used to describe late Pleistocene animals
throughout the world. We know that most species of mammals greater than 60 kg in
bodyweight became extinct at the end of the Pleistocene. ‘Megafauna’ is not a
taxonomic group nor is there a standard definition. Generally, the term
megafauna describes an animal that weighs 40 kg or more, but in Australia that
would result in including four species of living kangaroos (the grey, red,
antilopine and wallaroo) and probably excluding the extinct carnivore Thylacoleo
and the smaller Sthenurus (short faced kangaroo) (Murray, 1991 in Vickers-Rich
et al., 1991). Horton, (1984) came up with a tedious but more precise definition
for the Australian megafauna: ‘Animals that became extinct before the Holocene
and are large, either in an absolute sense or relative to other members of some
taxonomic rank, or are part of a taxonomic category all of whose members became
extinct and some of whose members are large.’ Fifteen genera and roughly
forty-one species of mammalian megafauna became extinct in Australia at the end
of the Pleistocene (Flannery, 1990). It should be noted that this essay is not
going to consider the many large birds (e.g. Genyornis) and reptiles (e.g.
Megalania prisca) which also became extinct during the Late Pleistocene. If
these non-mammals are added to the tally of extinctions, the number of
megafaunal genera extinct goes up to nineteen (Flood, 1990). A typical mammalian
megafaunal community consisted of a variety of forms, such as: Zaglossus;
Marsupial Lion Thylacoleo; giant wombats Phascolonus; long-beaked echidnas; the
Marsupial Tapir (Palorchestidae); Diprotodon (Diprotodontidae); and some
especially large morphs of the living Macropus (Macropodidae), (Murray, 1991 in
Vickers-Rich et al., 1991). The most deserving of the term ‘megafauna’, was
Diprotodon, which probably looked like a wombat ‘gone wrong’. Weighing in at
2000 kg, Diprotodon was a browser which preferred the drier open expanses of the
interior of Australia. The majority of the megafauna was herbivorous, such as
the cow sized Zygomaturus trilobus, the stumpy giant wombat Phascolonus gigas,
and the large macropods Procoptodon, and Protemnodon. A trend seen in the
megafaunal assemblage, that still exists with the extant fauna today, is the
distinct lack of carnivores (Flood, 1990). The Pleistocene carnivores were
limited to just three species: Thylacoleo carnifex, known as the ‘Marsupial
lion’ or the ‘giant killer possum’; the carnivorous lizard Megalania; and the
Tasmanian ‘tiger’, Thylacines. Thus, the large herbivores of Australia did not
co-evolve with a fleet of carnivores, like hyenas and canids and felids of
Africa. Flannery, (1994) believes it is the lack of carnivores that led to
faunas dominated by lumbering beasts that weren’t fast long distance runners
like those found in Africa. Flannery also suggested that being slow and naive to
predators, was a factor that led to their demise. One of the most frustrating
aspects of palaeontology is trying to place a fossil bearing rock into the
geological record. It wasn’t until 1945 when radiocarbon dating was first
applied in Australia, that the pieces of the megafaunal puzzle started to fit
together (Horton, 1980). Since then, dating techniques have improved. However,
there are still problems with dating bone so palaeontologists have had to rely
on stratigraphic association using more reliable, datable materials such as
charcoal and shell (Flood, 1990). Bone samples lose their collagen with time,
and are also susceptible to contamination, especially by younger calcium
carbonate carried down by groundwater. It is for these reasons that the exact
timing of the extinction of the megafauna is controversial. There are many Late
Pleistocene fossil sites found within Australia (Fig Martin last of the aus
meg). Of these sites, there a few that have narrowed down the timing of the
extinction event to somewhere around 20,000 years ago. (Fig Flood page 183).
These sites, in general, are all open sites situated in south-eastern Australia
(Flannery, 1990). Gilespie et al. (1978) describes a bone bed that contains up
to ‘10,000 giant marsupials’ at Lancefield Swamp in Victoria. The megafauna has
been dated fairly reliably, from charcoal in sediments directly below the fossil
bed, at 25,000 ? 800 BP and 26,000 ? 650 (Fig flood). There are other, less
reliable date, which may nevertheless support late existing Pleistocene
megafauna. Amongst these: Spring Creek, first dated on plant matter at 19,000 ?
390 BP (Flannery and Gott 1985), later revised to 35,000 BP (Flood, 1994);
Beginners Luck Cave, dated from bone collagen dates at 10,100 ? 200 BP, and
1,450 ? 210 BP (Murray and Goede, 1977, in Flannery 1990); and finally Lime
Springs, NSW bone fragments have been dated at around 19,000 to 6000 BP
(Flannery, 1990). If we take these dates as correct then we could have had
megafauna roaming around Australia as early as 6,000 BP or even 1,450 BP.
Unfortunately these are thought of as suspect. The bone from Beginners Luck Cave
has been interpreted as being an example contamination, and the bone from Lime
Springs is thought of by some as being reworked. The good news is that after all
the controversy surrounding dates of various sites, Cuddie Springs in semi-arid
New South Wales has provided sound information about the timing of extinction.
Cuddie Springs provides a secure stratigraphic succession which contains
abundant bones (Fig. Cuddie springs). A series of dates have been done on
charcoal that range from 30,280 ? 450 BP for the base of the succession to
19,270 ? 320 BP for the top. This means that Megafauna definitely existed in
Australia until 20,000 years ago. Unwanted Guests Much of the field of human
palaeontology is of little relevance to understanding the history of Australia
evolution (Flannery, 1994). This is because much of the evolution of man
occurred on other continents such as Africa and Asia. Until this year, it was
known from archaeological evidence in the Northern Territory that Aboriginal
people first arrived in Australia at least 60,000 years before present (Flood,
1994). Recent evidence suggests that we may have to re-write the text books when
it comes to human evolution. In mid-September of this year scientists discovered
in the Kimberly region of Western Australia, several enormous sculptured
boulders that had detailed circular engravings on them, (Woodford, 1996). This
rock art, which has been dated at up to 75,000 years old, may be the oldest rock
art in the world – more than twice the age of the French rock paintings at
Chauvet and Cosquer. While excavating the sediments below the art, ochre was
found dating up to 116,000 years, (Fig Sydney Morning Herald). Artefacts (stone
tools) were also found in a layer of sediment between 116,000 and 176,000 years
old. During the Pleistocene there were two major drops in sea level due to huge
amounts of water frozen in ice sheets. These glacial maximums occurred around
18,000 years ago, and 140,00 years ago (Flannery, 1994). This drop in sea level
resulted in much of the Australian continental shelf becoming dry land. This
made it possible to walk between Australia and New Guinea, and between Victoria
and Tasmania. Flood, (1995), describes how there was probably only a 90 km gap
of open ocean between Australia and Asia when the sea level was low. It is
thought that this enabled the first Australian’s to ‘island hop’ their way
through Asia to the north-west of Western Australia. Regardless of the actual
colonisation date, it is believed that Aboriginal people occupied most of
Australia by 35,000 (at least all favourable environments) (Flood, 1995).
Therefore, Aboriginal people would have of the environment in which they lived
with the megafauna. The exact nature of the co-existence between aboriginal
people and the megafauna is still controversial. Food for Thought I find it hard
to believe, being someone who has come into contact with mankind, that the first
Australian’s would pass up on the opportunity that the megafauna presented. The
megafauna would appear to have provided the Aoborigines with an excellent source
of food. Flannery, (1994) states that when Charles Darwin visited the Galapagos
Islands in 1835, he noticed the relative tameness of the animals there, and
proposed that it due to isolation of the islands. Australia has had quite a
unique history in that it as been physically isolated from the rest of the
world’s landmasses for over 40 million years. This long period of isolation has
given rise to an unique flora and fauna, that was largely derived from the
ancient supercontinent Gondwana. Flannery suggests that the absence of
significant carnivores in Australia, together with its long isolation, evolved
fauna that were naive to predators, let alone highly skilled hunter gatherers.
It was this naivity of the animals that contributed to their extinction. These
statements are problematic due to the lack of evidence to support them. Much
effort has been made in the search of evidence to support humans hunting
megafauna. This effort has only produced associations between humans and
megafauna (e.g. human artefacts and megafaunal bone). It should be noted that
these associations do not prove that megafauna were actively hunted, only that
they co-exsist in the same environments. There are Aboriginal legends that
describe how they hunted "giant kangaroos" (Flood, 1995). Flood also
describes how in the Northern Territory artwork has been found that many believe
depict Diprotodon. At Lake Menindee, NSW, bones of both extinct and modern
species have been found along with fireplaces and ‘Kartan-type’ stone tools (’Kartan’
is named after the large tool industry that was found on Kangaroo Island, SA) (Tindale,
1955). More recently, Liverpool plains in north-eastern NSW has produced three
sites which claimed to have humans associated with megafauna (Flood, 1995). Lime
Springs, is the only site of the three in which the findings have been
published. Lime Springs revealed many burnt bones belonging to Procoptodon,
Diprotodon, Macropus titan, Protemnodon, and Sthenurus, clearly associated with
stone tools and campfires in a stratigraphic succession. The sediments at Lime
Springs have been dated at 6,000 but as explained above they have been
interpreted as being reworked. Flood, believes that what probably transpired was
that a group of Aboriginal people camped on top of a sediment layer containing
megafaunal bones, the bones were burnt by their cooking fires, then everything
was subsequently blown into the swamp. There are other sites that show clear
associations between megafauna and humans such as: incisions and charring of
bones at Mammoth Cave, WA, (Archer et al., 1980); and aboriginal middens and
megafaunal bones at Lake Tandou Lunette western NSW, (Hope et al., 1983). What
scientists needed was direct evidence of slaughtering of the megafauna. On other
continents this problem was easily solved by the presence of abundant kill sites
(Martin, 1984). In Australia we have not as yet discovered major kill sites. At
a megafaunal site in south-western Victoria, Spring Creek many bones have been
found with cut marks on at least 3.8% of all the post cranial elements (Vanderwal
and Fullagar, 1989). Most of the marks are thought to have been a result of
Thylacoleo carnifex (Fig ***) gnawing on the bones. In 1984, a Diprotodon tooth
was found at the site that had twenty eight grooves notched into the surface of
it. It is almost certain that these grooves are man made (Fig **). It would be
very difficult to believe that Thylacoleo would have made such perfect grooves
in the tooth, and there is also the question why an animal would chew on a tooth
in the first place. Vanderwal and Fullagar suggest that that the engravings on
the tooth might be "tally marks for an ephemeral activity, or perhaps
doodles while passing away time". The only direct evidence that suggests
that Aboriginal people actively hunted megafauna comes from semi-arid NSW, at
the Cuddie Springs site (previously mentioned). Researches have found stone
tools within the succession with blood and hair on them, which was positively
identified to belong to Macropus titan and Diprotodon (Flood, 1995). This was
done by extracting DNA from bones of extinct species and then matching their
‘fingerprint’ with that of the blood residues on the stone tools. Flood points
out that this work is as yet unpublished. Nevertheless it indicates that
Aboriginal people were at least scavenging the carcasses of the dead megafauna.
How it Transpired The extinction of the megafauna is a subject that I believe
will remain controversial for years to come. Many theories have been proposed
that have a high degree of validity, but in general there are two schools of
thought when it comes to megafaunal extinction. Those that believe it was
climate induced, and those that believe that it was Anthropocentric (Flannery,
1994). Unfortunately this essay has not focused on the climatic model. If it
had, maybe my conclusions would be different. The essence of the model is that
Pleistocene megafaunal extinctions were a direct result of a dramatic world-wide
climate change (Horton, 1990). The environment changed too fast for the animals
to cope with and hence they died out. Several weaknesses with the climatic model
have been noted. The majority of the megafauna in Australia has managed to
survive 16 out of the last 17 major glaciations (Flannery, 1995); Pleistocene
extinctions occurred at different times and at different intensities in
different landmasses; There hasn’t been a good explanation as to why so many of