A study of the magnetic properties of an archaeological site in North China reveals human occupation far earlier than previously thought.
A team of scientists say they have uncovered evidence of early humans in China dating back at least 1.6 million years, the oldest signs of early humans in North China.
In a paper published in the scholarly journal Scientific Reports, Chinese Academy of Sciences geologist Hong Ao and his team determined that tools and other artifacts found at the Shangshazui Paleolithic site in China's Nihewan Basin were deposited there between 1.6 and million 1.7 million years ago. Previously, the artifacts were thought to be 1 million years old.
"[The site] represents the oldest evidence of early human occupation in North China," writes Dr. Ao, in an email interview.
Determining the ages of stone artifacts in North China is tricky; unlike the famed Olduvai gorge in Tanzania, rocks there don't contain volcanic materials suitable for radiometric dating.
So instead, the team used a technique known as paleomagnetism.
Since the late 1920s, when Japanese geologist Motonori Matuyama examined basalt rocks from different layers of earth in Japan. He noticed that the magnetic polarity of some of the rocks was reversed, all on rocks dating to the early Pleistocene or older.