Stone tools in China could be earliest evidence of human life outside Africa

Stone tools discovered in central China could indicate humans left Africa hundreds of thousands of years earlier than previously believed.

(CNN)The story of human evolution may need a rewrite after 2.12-million-year-old tools were found in central China.

The most ancient of these tools -- a collection of hammerstones, pointed pieces and scrapers -- are some 270,000 years older than what was previously thought to be the earliest evidence of human life outside Africa, according to a new paper in the journal Nature.
And scientists believe there may be even older tools at the site -- in Shangchen, in Shaanxi province's Lantian county -- that can't be accessed because of farming in the area.

Finding suggests 8,700-mile trek

    The team that discovered the tools was led by Zhaoyu Zhu, a geologist at the Chinese Academy of Sciences.
    In a paper published this week, Zhu and his colleagues detail how they dated the finds using a method known as paleomagnetism, which relies on changes over time in the Earth's magnetic field.
    A magnetic reversal that occurred between 1.26 million and 2.12 million years ago is evident in a stone discovered at the Shangchen site, the paper states
    The discovery suggests ancient humans traversed vast distances earlier than previously thought -- as far as 14,000 kilometers (8,700 miles), in this case -- from another proposed site of early human life in East Africa, according to the study's review in Nature.
    Before Zhu and his team's discovery, the earliest concrete signs of human life outside the African continent were in Dmanisi, Georgia. These included skeletal remains and stone tools, leaving little doubt about the validity of the findings.
    Though the China dig did not turn up human remains, the conditions on the site are unlikely to have caused a false positive. There are no ancient rivers in the area which could have naturally produced the types of shaped stones found, and no alternative hypothesis has been put forward about how the rocks could have been formed, the Nature review states.
      What remains a mystery is the identity of the people who created the objects. Without skeletal remains, it is difficult to accurately link the tools to Homo erectus or another species of early human.
      "An early form of Homo probably made the Shangchen artifacts, but it's too early to say if that was H. erectus," paper co-author Robin Dennell, an archaeologist at the University of Exeter, told ScienceNews.