The following article is based on a paper by Dr David Horton
in the Year Book of Australia 1994, updated with recent archaeological
evidence
Australian prehistory has undergone a revolution in scientific
understanding over the last 40 years. A century ago, the best
scientific estimate of the time of occupation of Australia was
400 years and as recently as the 1960s estimates still placed
human occupation of Australia at only 10 000 years. Since that
time there has been a rapid growth in research and field work
that has extended greatly the estimates of occupation of the
continent.
Aboriginal people have been living in Australia for more than
40,000 years, and on more recent evidence perhaps as long as
60 000 years or more. Archaeological field work has led to the
gradual discovery that Aboriginal people have been here a very
long time - as they have always said, and as their Dreaming
stories tell them.
Changes in climate and habitat
Another discovery of great significance has been that during
the long time of human occupation there have been great changes
in the geography and climate of Australia. Some 30 000 years
ago the country was mainly a pleasant place in which to live
- a place of greenery where giant animals roamed, lakes were
full, and the mountains were snow covered.
However, by 20 000 years ago the last great ice age had arrived.
This ice age extended from that time to around 15 000 years
ago. The land was even less hospitable than it is now, with
a vast central desert and sand dunes blowing in Victoria and
parts of Tasmania. The average temperature was perhaps 10 degrees
lower than the present and rainfall half its current level.
Cold dry winds scoured the continent and made life very difficult.
During this period, Aboriginal people faced severe stresses
on their food and water supplies and it has been speculated
that up to 80% of the population may have died.
According to research by Professor Rhys Jones at the Australian
National University, surviving populations migrated into refuges
in mountainous parts of the Pilbara, Kimberley and southeast
coast of Australia. They also survived in localised patches
of rainforest in Arnhem Land and Kakadu. Without these refuges,
the inhabitants would have become extinct due to climatic changes.
Westerly winds that now roar across the Southern Ocean then
blew across the middle of Australia, creating great mobile sand
dunes. At the other end of the continent, the impact on humans
was the opposite, with the Ice Age allowing hunter-gatherers
a greater land area in which to hunt as the tree cover was reduced.
Evidence for this new understanding comes from caves such as
one at Carpenters Gap in the Kimberley and Purit Jarra in central
Australia.
Temperatures started to rise 14 000 years ago and by 10 000
years ago the country was warmer and wetter than now, sparking
a widespread surge in plant growth and recolonisation, and leading
to optimum conditions for hunters and gathers. By 10 000 years
ago the vegetation patterns reached approximately their present
condition.
Through all this time sea levels were also fluctuating. At
their lowest point sea levels were more than 100 metres below
their present level and Australia formed one giant landmass
from the bottom of Tasmania through to New Guinea.

Two commonly used curves of sea level for the last glacial cycle.
Source: "Prehistory of Australia" by Mulvaney and
Kamminga page 106.
Changes in technology
Over such a long period, and with such major changes it is
impossible to imagine any group of people remaining culturally
and technologically static. Archaeological research has made
significant efforts to understand the kinds of responses which
Aboriginal people made to these changes.
Stone tools show little change through the period of first
human arrival to about 10 000 years ago. However, these tools
were mainly simple ones used to create other tools out of wood
and therefore it might be expected they would not change much
in form. These wooden tools rarely survive in the earth, but
we know from one unique archaeological find that boomerangs
and barbed spears were invented more than 10 000 years ago.
Rock art also shows changes in wooden tools and such other perishable
items as headdresses.
Around 5 000 years ago there was a radical change in the stone
tools themselves, with small, delicately worked points and blades
beginning to be produced. This change may have been associated
with the use of spears with stone points in place of spears
with sharpened wooden ends.
Changes in culture and art
Apart from material tools and technology, there have been cultural
developments of ultimately greater significance to Aboriginal
communities. These were reflected in many different styles of
rock art appearing in different
regions. There were changes in style over time from the ancient
engraved symbols to the colourful X-ray art of the north and
the vivid hunting scenes of east and west. Together with changes
in burial practices, such differences reflect changing religious
beliefs and rituals.
Economic change was also a feature of Aboriginal life. Several
thousand years ago the Tasmanians stopped eating fish. In the
north by contrast, large and complex stone fish traps were built
to harvest the sea's resources more efficiently. At some time
in the last 25,000 years the giant mammals become extinct and
at another time people begun using grindstones to make efficient
use of cereals and other seeds.
Regional differences in language, religion, social organisation,
art, economy and material culture arose over time. Patterns
and routes for trade in materials and technology developed.
Goods could travel all the way from the north to the south of
the continent or from east to west. Not only goods traveled
these routes, but ideas, songs, ceremonies and news all moved
with the people carrying baskets of pituri or ochre on their
heads or bundles of spears on their shoulders.
Changes in trade and communication
Rising seas affected weather patterns and the environment -
and perhaps most significantly of all they affected some aspects
of communication. In the north there was no longer a trade route
by land, but the many islands of Torres Strait continued to
provide for sea trade between Cape York and New Guinea. In the
south, however, the distances were too great and around the
time the boomerang was being invented, the Tasmanians lost touch
with the mainland. Since that time, Tasmanian peoples lived
their lives in isolation from the rest of the world until the
arrival of Europeans that proved so disastrous for them and
their way of life.
On the mainland the process of communication, trade and growth
in cultural diversity continued - to the point that there were
around 250 distinct Aboriginal languages
spoken on the continent at the time of first contact with European
visitors. Cultural diversity - and vigorous response to changing
circumstances - continues today amongst contemporary Aboriginal
Australians.
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