A publication of the Archaeological Institute of America
The ancient fossil site of Renzidong (Renzi Cave) in Anhui Province, eastern China, is yielding animal bones and possible stone tools showing that Homo erectus may have established itself here 2.25 million years ago, more than 400,000 years earlier than previously thought. Renzidong appears to be the oldest among a growing number of sites suggesting great antiquity for hominins (humans and close ancestors) in East Asia. The site, a large fissure, is also fueling a debate on the origins of our genus Homo, with some Chinese scientists proposing an evolution of H. erectus in China parallel to that already observed in Africa.
Renzidong was discovered in a Fangshang County cliff face as workers were quarrying surrounding limestone. Digging for two years now, excavation leader Jin Changzhu of Beijing's Institute for Vertebrate Paleontology and Paleoanthropology and Han Ligang and Zheng Longting of Hefei, Anhui Province, have found some 3,000 bones of animals that had fallen into the fissure. Among nearly 60 species represented, the elephant-like Sinomastodon, an ancient tapir, and the monkey Procynocephalus show that Renzidong was open briefly between 2.5 and 2 million years ago.
But the most exciting evidence is archaeological: about 50 stones and bones fractured to make flakes and scrapers. Early hominins apparently descended into the fissure to butcher the animals that fell in. The problem is that their technology in East Asia was simple; archaeologists frequently have trouble distinguishing real knapped tools from similar objects splintered by natural forces. Moreover, fissure infills never preserve the kind of evidence of habitation we know so well from contemporary sites in East Africa, such as at Tanzania's Olduvai Gorge. But the 1999 campaign began to show something different. The skeletons of a mastodon and a tapir, both victims of falls, were found together in the dig's lower levels. The mastodon bones lie piled along one wall, while the tapir remains seem to have been laid out for butchering; tools were found scattered about. Under this stratum there appears to be a level of Procynocephalus skeletons. This primate, like H. erectus, preferred open environments. Fossils of H. erectus and similar monkeys are often found together at Asian and East African sites.
Renzidong is comparable to a half dozen other sites in China dating (more or less convincingly) to between 1.8 million and 800,000 years ago. A limestone cave site not far from Renzidong lies at the center of the East-West debate over the origins of Homo. A few score stone tools and Pliocene (5-1.8 million years ago) mammal bones were found at Longgupo ("Dragon Hill") in Wushan County, eastern Sichuan Province (see "The First Asians," January/February 1996). Our own geochronological studies suggest the infill is nearly 2 million years old. Longgupo has produced tantalizing fossils of Procynocephalus and Homo, the latter including a jaw fragment with two very worn molars. For some Western scientists, the teeth share features with earliest Homo in East Africa--leading us to suggest a direct link, a "dispersal" of African hominins to East Asia about 2 million years ago. But Chinese paleoanthropologists tend to see these same primitive features as deriving from Asian apes and suggest a local Asian origin for H. erectus. Renzidong supplies this "Asian hypothesis" with tools as old as any fashioned by H. erectus in Africa, but most Western scholars favor an early dispersal of Homo out of Africa into Asia, few would support an Asian origin of the genus Homo. The Pliocene record of hominins in Africa preceding Homo is extensive, while such a record has yet to be unearthed in Asia.
Both sides of the culturally charged hominin-emergence debate point to the effect of plate tectonics in climate change. Between 9 and 4 million years ago, the convergence of the Indian and Eurasian continental plates gave rise to the Tibet Plateau, which caused the climates from East Africa to East Asia to become more seasonal and arid. Western scientists believe that these events triggered forest-dwelling apes in equatorial Africa to beget open-dwelling hominins. But Chinese scientists use the tectonic evidence to suggest a parallel hominin emergence in East Asia. In their view, a ten-million-year-old forest ape was the putative ancestor of H. erectus, orangutans, and the extinct Gigantopithecus, the largest ape that ever lived. With Longgupo's primitive teeth and Renzidong's ancient stone tools, the Asian hypothesis is gaining (mostly Chinese) converts.
Whether one favors African or Asian origins, early hominins were ferociously migratory, and this led to the worldwide diaspora of our species, H. sapiens. Early humans repeatedly passed between Africa and Asia, and their movements correspond to those of other large mammals, including carnivores--early Homo and the dagger-toothed cat Megantereon, the remains of which have been found at Renzidong, could have been such traveling companions.
Are the Renzidong tools real? Do the half dozen other Chinese sites reveal the earliest colony of dispersing African hominins--or do they constitute the heartland of the genus Homo? While the Chinese sites pose interpretive problems, the Asian hypothesis for the origin of Homo has energized Chinese scientists and loosed important funding from the Chinese Academy of Sciences and other Beijing-based government agencies.
Russell Ciochon and Roy Larick of the University of Iowa have authored a book about early dispersals of Homo erectus for Oxford University Press.