Final answer:
Paleoanthropology is the branch of physical anthropology that studies ancient human fossils like Lucy. Donald Johanson discovered this important 40% complete skeleton, which has provided significant insights into human evolutionary history and the genus Homo.
Step-by-step explanation:
The field of physical anthropology that studies skeletal remains such as Lucy's is called paleoanthropology. Lucy, an adult female Australopithecus afarensis skeleton discovered in the mid-1970s, provides crucial evidence in human evolutionary studies. The skeletal morphology and associated fossil evidence allow paleoanthropologists to hypothesize about behavioral and physiological characteristics of early human ancestors, revealing insights into the evolutionary history of the genus Homo. Experts like Donald Johanson, who discovered Lucy in Ethiopia, play a significant role in uncovering our ancient past through meticulous examination and analysis of these key finds, such as those found at the Afar region of Ethiopia.