Homo Erectus is to be the first of our kind to walk fully upright and was traced near the Bengawan Solo river on the Indonesian island of Java. The small number of partial skulls and two shinbones found near the river in the 1930s have finally been dated between 108,000 and 117,000 years old. This discovery confirms Central Java as Homo erectus have ceased to exist after roaming the planet for 1.8 million years.
“This is the largest collection of Homo erectus fossils at a single site in the world, and dating it has always been important,” said Russell Ciochon, an anthropologist at the University of Iowa. “This was a very long-lived species, and we have now nailed the date of their last appearance.”
Dating the fossils
The bones were discovered on the Ngandong terrace by Dutch geologists between 1931 and 1933. Scientists had a hard time to date this site as they came up with inconsistent dates 27,000 to half a million years old. Together with a crew from the Institute of Technology in Bandung, Indonesia, researchers tried for 16 years to date the site with the help of the previously discovered data from the Dutch geologist. Data from the journals and maps that were translated into English.
The journal Nature explains how the scientists dated the Homo erectus fossils based on the landscape, animal fossils found on the same site as well as studying the stalagmites in the caves nearby. This proofs that the mountains rose at least half a million years ago, diverting the Solo river into Kendeng hills where the Ngandong terrace sits.
Scientists say that the Ngandong terrace developed between 140,000 and 92,000 years ago. As hard as it was, researchers managed to locate the bone bed where hundreds of more fossils were found, though none belonged to Homo erectus.
Kira Westaway, who co-led the study at Macquarie University in Sydney, believes that “Knowing when a species was alive and when they eventually died out is important for understanding where they sit in the evolutionary tree, who they interacted with, and why they became extinct.”
Are we sure that the fossils from Java belong to Homo Erectus?
It looks like Homo Erectus did not co-exist with Homo Sapiens, but they may have lived in the same time as Denisovans that lived in the cold caves of Siberia after emigrating to south-east Asia. The scientist’s hard work shows that Homo erectus finally went extinct on Java due to climate and land changes.
“It’s an important result because it nails down the time span of this highly successful, cosmopolitan, and long-lasting species,” says Josephine Joordens, a paleoecologist at the Naturalis Biodiversity Center in Leiden.
Mark Maslin, a researcher at UCL, said: “Even more exciting is the realization that around 100,000 years ago, there existed at least seven or eight different hominin species including our own, Homo Sapiens. From this complex bush of ancestors, only one species emerged, our own, which finally arrived in Java 35,000 years after the last known appearance of Homo Erectus.”
“The question I’m asking is why should we think that these fossils are Homo erectus?” asks John Hawks, an anthropologist at the University of Wisconsin-Madison. “It’s hard for me to see a population of fossils from Java 120,000 years ago and not assume they were probably Denisovan.”