An expert cleans old coins found in the Nanhai No 1 shipwreck. XINHUA
Where did the ancestors (祖先) of modern humans come from? It is commonly believed that they came from Africa. But an archaeological (考古的) discovery at the Jiegedong Paleolithic cave site (疥疙洞旧石器时代洞穴遗址) in Shaanxi implies (表明) other possibilities.