Picture taken at the site of the discovery of ancient tools in China. Photo: Prof. Zhaoyu Zhu

Tools and artifacts made of stone, found hundreds of feet deep in ancient sedimentary layers, may now indicate hominids left Africa and made it all the way to modern-day China, hundreds of thousands of years quicker than previously believed, according to a new study.

The used scrapers, cobble, notch, hammer stones, pointed pieces of rock and other items were in layers on the Chinese Loess Plateau. They were dated to 2.12 million years ago, based on paleomagnetic dating, according to the new paper in the latest issue of Nature.

“Our discovery means it is necessary now to consider the timing of when early humans left Africa,” Robin Dennell of the University of Exeter, along with 10 fellow scientists from China, said.

The artifacts were found in 17 different layers starting at about 40 meters, and extending to a depth of more than 70 meters, according to the paper. They were mostly made of quartzite and quartz, and all had been intentionally flaked.

The paleomagnetic dating method was used to date each layer.

Minerals in each layer contain a record of the direction and intensity of the magnetic field of the Earth at the time point in time, so it becomes somewhat of a soil time capsule.

In this case, progressive thermal demagnetization was conducted on 722 specimens with an average sampling interval of 10cm, according to the paper.

Accordingly, based on the variation that gradually presented itself in the magnetostratigraphical layers, the artifacts’ age was placed on the timeline.

The earliest items, at 40 meters, were about 1.3 million years ago. But the oldest, beyond 70 meters, were more than 2.1 million years old, the researchers concluded.

Also found in context of the oldest tools were the remains of animal bones.

If confirmed by other researchers, the paper could upend some timelines, according to the scientists. For instance, the previous earliest appearance of the genus Homo was just 1.85 million years ago from the country of Georgia. The finding in central China is 270,000 years older still, and is thousands of miles farther beyond the limits of Africa, long considered the “cradle of humanity.”

Excavations from Africa, Europe and Asia continue to rewrite timelines about humanity’s earliest ancestors.

For instance, a study last fall in the Proceedings of the Geologists’ Association found that fossilized footprints in Crete showed a bipedal upright hominid from a staggering 5.7 million years ago, though that study has been considered controversial by many.