Why modern man left Africa 100,000 years ago to conquer the rest of the world remains controversial. Currently, it is believed that the driving force behind his wanderlust might have been a combination of climatic changes in his native homelands and the development of new weapons technologies, which provided better food supply for population growth and, consequently, increased resource pressure.
Homo sapiens, however, was not the first of the group of Hominini who left Africa. At least two million years ago, Homo erectus had already set off for Asia and, ultimately, Europe, probably for the same reasons. The oldest known human remains beyond the African continent were unearthed in the early 1990s east of the Black Sea in Georgia. Dmanissi’s famous skull and skeletal fragments are 1.8 million years old, indicating that Homo erectus was probably the very first “global player” among human species.
But do these bones actually represent the beginning of the worldwide spread of the genus Homo? Or did emigration start even earlier? An international team led by Zhaoyu Zhu of the Chinese Academy of Sciences has now published a series of findings in the journal Nature, including numerous stone tools found in the rugged hills of Shangcheng in the south of the loess plateau in northern China, which far outshine comparable discoveries.
What makes this discovery so spectacular is the dating of the sediment layer, in which the uniquely worked stones were found: using palaeomagnetic methods, the researchers came to an age of about 2.1 million years. These are likely to be the oldest traces of human activity outside of Africa.
The finds consist mainly of round stones and severed stone fragments, which differ significantly from the locally found natural stone deposits. The researchers suspect that these tools were brought in from afar and had been made elsewhere. Moreover, the analysis of the finds underlines the dating: the method used to process these stones is in many ways similar to tools from the same period produced by Homo erectus in Africa.
What these tools were actually used for is largely unclear. However, bones from cattle, deer and pigs that appeared in the same foundations indicate that they may have been used for cutting game. The migration rate of Homo erectus can also be deduced from these findings: If the dating of the stone artifacts is accurate, our ancestors needed about 1,000 to 3,000 years for the 14,000 kilometers between Africa and Southeast Asia — that is about five to 15 kilometers per year.