AUSTRALIA'S TWO HUMAN INVASIONS

The material of this page was first published in 1976 by Rigby Ltd., Adelaide. Since then, Australia's population has increased by about 30 % and the exploration of mineral resources has widened. In all probability, offsprings and immigrants have mainly increased the coastal population. Many of the other data will have undergone refinement, but are unlikely to have changed the overall picture.

It is now known that Man's first invasion took place on foot and by means of rafts from the north over the interrupted land bridge from Asia some 30 000 years ago. By the time of the second invasion, the Aborigines had adjusted themselves to a wide range of climatic and survival conditions. They inhabited the continent more or less densely, with some crowding along certain parts of its coast as early European explorers have referred to the presence of fires along most of the shoreline.

The Old Australians gathered food from land and inshore regions in a random fashion. They used only fire to modify their environment, and left no traces of their existence apart from campfire ashes, stone tools, middens of cockleshells, cave drawings and their bones.

Within a few years of the second invasion, the New Australians had radiated from centres on the east, south and west coasts into the continent. The interior challenged the early explorers, who were soon followed by farmers, graziers, naturalists, geologists and miners. Well into the twentieth century, the image of these settlers was that of the pioneer who worked the land, rode a horse and shielded himself from the sun with a wide-brimmed hat. As he penetrated large sections of the continent, he changed the surroundings on his path. He burned the bush, killed native animals and Aborigines, ploughed the topsoil, sent his imported animals out to graze and fenced in large areas. He thus destroyed a balance Nature had established during an almost infinite past.

When this self-imposed task of cultivation, using methods which since have been proved to be inadequate for Australia, was approaching its end and modern machines reduced labour needs, most settlers flocked back to the coast and became urbanized. By 1971, 80% of Australia's population of approximately thirteen million inhabited an area of about 7000 square kilometres, or less than 0.1% of the total area of 7 700 000 square kilometres; 85% lived within 80 kilometres of the 20 000 kilometres long coast.

After 200 years of colonization, the New Australians once again face a great unknown: an ocean which covers 70% of the Earth's total surface of 510 000 000 square kilometres. Today, civil, mechanical and chemical engineers, architects, harbour masters, fishermen and holiday makers ask many questions which cannot yet be answered definitively, because in the past little effort had been devoted to observation and measurement of the many parameters of Australia's environment.

At most locations around Australia's coast, recording and observations of environmental parameters had to start from scratch. As the lengths of the time series for such quantities as temperature, wind speed and direction, solar radiation, tidal height, and ocean current speed and direction, etc. grew, a basis was established for short term predictions. Eventually, after a reasonable coverage of the coast has been made, interpolation for many variables between locations with good and long records should yield first estimates at new locations.

Rainer Radok: Scjrr@mucc.mahidol.ac.th.
28/2 Mu 13 NongNae 24120 Thailand