The Zhoukoudian caves, China's most famous paleontological site near Beijing, were discovered in 1918 and they continue to yield surprises. Nature
says that a total of more than 17,00 stone artifacts have been found there, in addition to fossils of 50 Homo erectus
, including six skulls. This species had a barrel-shaped torso and was about 145-180 centimetres tall. It walked upright in a way that was similar to Homo sapiens
, i.e. modern humans.
The fossils were previously thought to be about 230,000-500,000 years old, but a new dating method has shown that they are actually about 700,000 years old.
The reason that the previous dates were so imprecise has to do with the nature of the Chinese sites. They do not contain volcanic ash, which can be easily dated. The new method is based on the influence of cosmic rays on aluminum and beryllium.
The new dating method is exciting because it is expected to answer some questions about the migration of Homo erectus
into northern China and to Java in Indonesia, something that happened at least 1.6 million years ago, whereas the species evolved in equatorial Africa, around 2 million years ago. It is thought that Homo erectus
may have survived in Indonesia until about 50,000 years ago.
Philip Rightmire, a palaeoanthropologist at Harvard University, says that the new dates show that the Homo erectus
of Zhoukoudian developed physically in a way similar to the African fossils found at Algeria's Tighenif site.