Perhaps they set out in search of food, or maybe it was simply wanderlust. But at some point early humans left their African homeland and began to colonize other regions of the world. Scientists have only begun to formulate an understanding of the timing of these early migrations. Findings reported today in the journal Nature may thus shed some much-needed light on the matter.

Researchers led by R. X. Zhu of the Chinese Academy of Sciences in Beijing have dated a large assemblage of stone tools excavated from northern China's Nihewan Basin at 1.36 million years old. As such, these remainsconsidered the handiwork of Homo erectusprovide the earliest evidence of humans in northeast Asia. In the past, the ages of such Paleolithic sites in east Asia have proved controversial, owing to a lack of materials suitable for isotopic dating methods. But Zhu's team arrived at their age estimate using the so-called magnetostratigraphic approach.

"The spread of toolmakers to [a latitude of at least 40 degrees north] implies that early Pleistocene human populations in east Asia were able to adapt to diverse climatic settings," the team writes. Indeed, these intrepid explorers seem to have emerged from tropical Africa prepared for the heightened climatic variability of the time, including the intermittent drying out of northern China.