Final answer:
Early humans reached Australia by using primitive watercrafts, such as rafts or boats, due to the absence of land bridges to Asia during that period. This conclusion is supported by archaeological findings and the knowledge of how our ancestors adapted to various environments around the world.
Step-by-step explanation:
Hominins, including modern humans, reached Australia not by walking but by watercraft. During this period, Australia was not connected to Asia by land, which strongly suggests that early humans used some type of rafts to traverse the waters that separated the continents. This is supported by archaeological evidence such as discoveries of human habitation in Australia dating back to thousands of years ago. The absence of land bridges implies that humans accomplished intercontinental travel across open water. Furthermore while during an ice age humans could travel overland on the Bering Land Bridge from Asia to Alaska, the journey to Australia required sea travel.
This early human migration showcases the remarkable adaptability and ingenuity of our ancestors, who were able to carry out transcontinental and transoceanic voyages well before developing technologies associated with advanced civilization. A study of global human migration reveals that the early hominins adjusted their survival strategies for different environments, learning to hunt local animals and gather region-specific plants. These innovations often coincided with significant environmental impacts, such as the decline of certain animal species. However the need for these early humans to cross bodies of water to reach continents like Australia is a clear sign of their enterprising nature and capability to create primitive watercrafts as evidenced by later migrations to the Pacific Islands using seagoing canoes.