In a groundbreaking study, researchers have uncovered evidence of early hominin presence on the Indonesian island of Sulawesi during the Early Pleistocene. This revelation, derived from palaeomagnetic and dating analyses, provides a new understanding of human evolution and migration patterns in Southeast Asia.
The study, conducted by a team of geologists and archaeologists, involved meticulous palaeomagnetic analysis of block samples collected from the Calio excavation site and surrounding areas. These samples, carved with precision from fresh excavation baulks and field exposures, were analyzed to determine the magnetic properties of the sediments.
Palaeomagnetic Analysis: Unlocking the Past
The palaeomagnetic analysis involved the use of oriented block samples, each approximately 10 × 10 × 10 cm3, carved from various locations. The samples were carefully measured using a Brunton Compass, corrected for local declination, to determine their strike and dip. Due to the scarcity of suitable layers, some samples were taken from outcrops up to 430 meters from the main Cabenge–Pampanua road.
Once collected, the samples were tightly packed and shipped to the Palaeomagnetism Laboratory of the Centre for Geological Survey in Bandung, Java. Here, they underwent further analysis, including step-wise demagnetization using both alternating-field and thermal methods. The study revealed that most samples exhibited a reverse polarity, suggesting a minimum age of 773,000 years, corresponding to the Brunhes–Matuyama boundary.
“The characteristic remanent magnetizations (ChRMs) isolated at 20–40 mT and 200–300 °C indicate that magnetite is the dominant carrier of remanence,” the researchers noted.
U-Series and ESR Dating: Pinpointing Ages
Complementing the palaeomagnetic data, U-series dating was performed on Celebochoerus fossil teeth found at the site. These analyses were conducted using laser-ablation multi-collector-inductively coupled plasma mass spectrometry at Southern Cross University. The results provided critical insights into the age and environmental conditions of the site.
Additionally, electron spin resonance (ESR) dating was applied to the Celebochoerus teeth, offering further evidence of the site’s antiquity. This method involved careful preparation and irradiation of tooth enamel, followed by precise measurement of ESR intensities. The findings suggest that the site dates back to a period well within the Matuyama Chron, with some samples potentially correlating to the Olduvai Subchron.
“ESR ages were calculated using both the US-ESR MATLAB program and the DATA program to ensure accuracy,” the study reported.
Stone Artefact Analysis: Tracing Hominin Activity
The study also included a comprehensive analysis of stone artefacts excavated from the site. Using both qualitative and quantitative methods, researchers assessed the artefacts’ condition, material, and technological attributes. The artefacts, predominantly made of chert, were analyzed for technological length, width, thickness, and platform characteristics.
These artefacts provide valuable insights into the technological capabilities and cultural practices of early hominins in the region. The analysis revealed a range of flake types and retouching scars, indicative of sophisticated tool-making techniques.
“The stone artefacts from Calio exhibit a high degree of technological sophistication, suggesting advanced cognitive abilities among early hominins,” experts noted.
Implications and Future Research
This study not only sheds light on the presence of early hominins in Sulawesi but also raises intriguing questions about their migration patterns and interactions with other hominin groups. The findings suggest that Sulawesi may have been a significant waypoint in the broader narrative of human evolution.
Future research will focus on expanding the sampling density in the stratigraphy to confirm correlations with known subchrons and further refine the timeline of hominin activity in the region. Additionally, ongoing studies will aim to explore the environmental and climatic conditions that may have influenced hominin settlement and survival on the island.
As researchers continue to uncover the secrets of Sulawesi’s ancient past, this study serves as a testament to the power of interdisciplinary collaboration in unraveling the complex history of human evolution.
