|Photo by: Cristian Chirita via Wikimedia Commons|
The period and method of the first humans to arrive in Australia has remained a topic of vibrant and protracted debate among archaeologists and continues to evolve to this day. Australia, being the end point of early modern human migration from Africa, bears a significant role in deciphering the story of human evolution.
It is accepted that anatomically modern humans appeared in Africa over 200,000 years ago and China around 80,000. Many archeologists say the first people appeared in Australia 47,000 years ago. However, in recent years, scientists have steadily pushed the period of human settlement in Australia further back in time because of many unanswered questions regarding the period, means, and routes of dispersal from Africa.
Recently, a team of researchers and archaeologists from the University of Washington, University of Notre Dame Australia and the University of Wollongong has found and dated artifacts in northern Australia that put the arrival of humans in the region at about 65,000 years ago. The findings were published on 20th of July in the journal Nature, describing the artifacts found at the Madjedbebe archeological site and the dating techniques used on them.
In 1989, a previous excavation in the area had revealed evidence of human activity at 60,000 to 50,000 ago, but archaeologists were reluctant to embrace the idea. Among the arguments brought forth was the presence of sandy deposits in the area, which some scientists thought must have made it easy for the artifacts to be moved into lower layers by burrowing and trampling animals. Some of them argued that the measured ages of the sediment layers were not precise enough to support the dates.
The debates continued to intensify since the 80s. At some point, analysis of DNA from the hair of an Aboriginal man who lived 100 years back suggested that Australians of the Aboriginal descent separated from early Asians between 62,000 and 75,000years ago.
Furthermore, some theories supported by evidence of climate change implicated humans in megafaunal extinction between 45,000 and 43,000 years ago. The argument was that people migrated into the region, scrambling for resources and disturbing their habits, thereby causing the collapse of unique megafauna such as giant kangaroos, tortoises, and wombats among others.
The team of researchers worked together with the Mirarr Aboriginal natives, after a landmark agreement between the University of Queensland (represented by the relevant scientists) and the Gundjeihmi Aboriginal Corporation that represents the Mirarr traditional owners of the land in question. According to the researchers, the agreement gave the Mirarr senior custodians ultimate control over the excavation process and oversight of curation of the materials.
During the excavation, scientists kept three-dimensional records of the coordinates of over 10,000 stone artifacts using a laser total-station, which uses a laser and prism to map the location of objects and other features within millimeter accuracy. After analyzing the coordinates, they disapproved previous criticism that objects may have moved. They did so by finding broken artifacts that could be matched, and the distance between them gave a clue as to how far they had been moved. They also experimented to examine the movements of artifacts in the ground due to the activity above, which further enabled them to rule out the possibility of the tools having been mixed between the three distinct sediment layers of occupation that were found.
The team collected over 100 samples which were dated using both radiocarbon dating and Optically Stimulated Luminescence (OSL) methods. They had to rely on OSL to find the ages of the lower layers at the site because Radiocarbon dating is limited to a maximum of 50,000 years.
For more accuracy, they used the dating techniques on thousands of separate sand grains rather than a group. They also shared their samples with another lab for analysis just to be sure. Finally, the team of scientists came up with compelling evidence that settlement at Madjedbebe and Australia, in general, began 65,000 years ago.
These discoveries have shed some light on the overall picture of human evolution. For instance, it suggests that modern humans and Homo floresiensis found in Indonesia may have lived together for about 15,000 years, which is an indication that the dawn of modern humans did not necessarily cause the extinction of other ancient human-like species. More so, the fact that people lived in Australia since 65,000 years back proves that humans and megafauna co-existed for 20,000 years before the latter went extinct.
In the study published, the researchers also pointed out that they found evidence of mixing of ochre with reflective powders made from ground mica, probably to make a vibrant paint. These findings suggest that the people who lived made use of artistic expressions. They also unearthed new forms of stone tools such as edge ground hatchet heads and grinding stones. The grinding stones indicated the humans there ground a range of seeds, fruits and other plants for food.
Pieces of burnt pandanus nuts, yams, and fruit seeds were also recovered in fireplaces, giving clues of the earliest diet at the site.Archaeologists around the world have agreed with the findings of the excavation at Madjedbebe majorly because it co-relates to the already known first modern-day human migration theory.