Lost and found: two million-year-old ‘playground’ discovered in northern China
At an eroded basin in Hebei province researchers have discovered what could be a “playground” of early hominids nearly two million years ago.
Examination of stone artefacts between 1.77 and 1.95 million years old suggested that they could be toys played with by children.
“This is an amazing discovery,” said professor Wei Qi, paleoanthropologist with the Chinese Academy of Sciences and lead scientist of the project at the Heitugou site in Nihewan basin, Yangyuan county.
“The site is a treasure chamber that may hold some useful clues to answer a lot of important questions, from the social structure of the early hominids to whether, when and how they arrived in Asia all the way from Africa.”
The “playground” was not big, but seemingly bustling with activity.
In an area less than 6 square meters, scientists found more than 700 stone artefacts with nearly 20,000 fragmented pieces.
Wei, now retired and spending most of his time at the site, believed that these stone pieces were made by the hands of children and women.
More than 80 per cent of them were small, ranging 20 – 50mm in length, with most carrying no sign of wear by use at all.
One artifact, tagged HTG268, caught Wei’s special attention. In his opinion it could be a toy or gift made by a mother for her child.
“You can almost feel the maker’s love and passion, which was deeply embedded in this piece,” he said.
“It was so finely made and beautifully shaped, its quality could rival the stone artefacts of much more recent periods.”
There is other evidence suggesting the site was a playground instead of a living or working area.
Researchers failed to find large amount of animal remains that are common in a habitat, and the near absence of large size stone tools could be a sign that few adult workers were involved in these activities.
A big challenge was to determine the age of these stone artefacts, Wei said.
Though the site was discovered as early as 2002, it was not until recently that the scientists were able to date it with any certainty.
Using a geochronological tool called magnetostratigraphy, which analyzed the direction change of the ancient Earth’s magnetic field that was recorded in the site’s sediment, the scientists found the Heitugou site to be older than the famous Dmanisi site in Georgia, which was regarded the earliest known hominid site outside of Africa.
Wei said they would report details of their findings in a research paper, which had been submitted to a top archaeological journal in China.
The excavation was carried out with utmost care, he said. Each artifact had been documented and photographed in the sediment before retrieved.
Wei said researchers were surprised by the “freshness” of the artefacts.
The concentrated distribution and little wear showed that they were buried by a sudden event, likely a landslide, which protected them from later exposure to winds and precipitation.
Before the catastrophic event, the playground was likely a small paradise.
Nihewan basin, now a rugged landscape with deep gorges, used to be an enormous lake which provided an ideal habitat for early hominids. In the past century, researchers have discovered numerous early hominid sites in the area.
Children and their mothers could feel safe enough to sit by the lake making large amounts of stone toys. The scant animal fossils discovered at the Heihegou site were all herbivores such as elephants and rhinoceros.
But Wei’s discovery at the Heitugou site was not without controversy.
Gao Xing, researcher with the CAS Institute of Vertebrate Paleontology and Paleoanthropology, said the biggest concern was whether the stone pieces were all made by hand.
“It is difficult to rule out the possibility that they were just stone fragments created by natural forces. They were too old, too preliminary. To determine whether they were hand-made artefacts may go beyond the limit of science today,” said Gao, who had visited the site.
“Future studies would be much needed. The Heitugou site has potential for significant discoveries, though it imposes some enormous challenges to paleoanthropologists.”
Wei said he was sure that the stone pieces were hand made. If they are not, most stone pieces in museums today would be a subject of doubt, he said.
But he admitted that the discovery brought up some difficult questions.
It is commonly believed that the first hominid ventured out of Africa about 1.8 million years ago, via a route from Europe to Asia, but if there were hominids in China at the same time, the date or route of the expansion should be reconsidered.
“The Heitugou site does not challenge the ‘Out of Africa’ theory, it’s not old enough,” Wei said.
“But the timing is very interesting and it could open a door to new discussions about hominin origins.”