Scientists say a new age estimate for the skull of an early human is raising questions about modern human ancestry. The fossilized skull was considered a major discovery when it was found in Zambia in 1921. It was the first fossil of an extinct human species to be discovered in Africa. The skull was named after the area in which it was discovered, Broken Hill. Researchers say a new examination of the fossil suggests that it is much younger than previously thought. The fossil was difficult for scientists to date. That is because the skull was recovered in a mine that later became completely destroyed from mining operations.