Answer:
Human life began in Africa first and then moved around the world.
Step-by-step explanation:
The two competing theories about how and where humans came about that Donald Johanson, discoverer of Lucy, be most likely to support is "Human life began in Africa first and then moved around the world."
This is because Donald Carl Johanson was an American Paleoanthropologist who in 1974 found a female hominin australopithecine skeleton, in Hadar, Ethiopia dated 3.2 million-years-old.