Final answer:
Olduvai Gorge in northern Tanzania is the site often referred to as the "cradle of humankind" where many early hominin fossils have been found, including the famous Lucy discovered by Donald Johanson, and significant work by Richard and Mary Leakey.
Step-by-step explanation:
The ravine in northern Tanzania where many early hominin fossils have been recovered, often referred to as the "cradle of humankind," is b. Olduvai Gorge. Notable anthropologists such as Donald Johanson, who discovered Lucy, and Richard and Mary Leakey, who have done significant work in this area, have contributed to our understanding of early hominids. Since the 1970s, remains of hominids dating back to about 10 million years ago have been discovered in the Great Rift Valley, specifically at Olduvai Gorge. This site has provided invaluable insights, indicating that early hominid species might have lived in the region for millions of years, shaping our understanding of human evolution.
Discoveries in other areas, like the Rising Star cave system in South Africa where Homo naledi was found, as well as other regions like Blombos Cave, also contribute to our knowledge of early human behavior and cultural development.