close relationships among Peking man and Pithecanthropus Erectus.

Davidson Black inferred that the Peking man was 'a thinking being, standing erect, dating to the beginning of the Ice Age.' Some scientists were skeptical of Black's findings, and in 1928, while Black was traveling to validate his beliefs to other scientists, half of a lower jaw was found with three teeth still intact. But the evidence he was really looking for was in the discovery of skull of the first Peking man.

In 1932, Black was elected a Fellow of the Royal Society. His hard work and dedication carried him far in his experiments and discoveries, but the stress eventually got to him. He struggled with a congenital heart defect, which when he overworked would act up. He worked long days at his office, often returning again to work during the night, with very minimal sleep. This obsession eventually lead to his death at age 49, in March of 1934, while working alone in his office at night.

V. Revising the present perfect continuous tense