Final answer:
Extensive evidence of Homo erectus, including larger brain size and tool use, has been found at Zhoukoudian. This species is known for its similarities with modern humans and has a significant number of undiscovered fossils in the cave.
Step-by-step explanation:
The fossil remains of Homo erectus discovered in the 1920's and 1930's as well as more recent excavations at Zhoukoudian are by far the most extensive evidence of this early human species. Homo erectus appeared approximately 1.8 million years ago, and it is believed to have originated in East Africa before migrating out of the continent.
Fossils of H. erectus have been found across various regions including India, China, Java, and Europe. This species exhibits features more aligned with modern humans compared to earlier hominins, such as larger brain size, reduced sexual dimorphism, and usage of fire and tools.
Furthermore, evidence from Zhoukoudian indicates that H. erectus was hunting, cooking, and possibly had the practice of a home base. The site continues to be significant, with paleontologists estimating that many more fossilized bones are still to be discovered in the cave, which could provide additional insights into the life of H. erectus.