Origins

It’s not often you see a paper that announces “I was wrong,” especially if you’re reading journals like Science and Nature. But that’s what paleoanthropologist Russell Ciochon of the University of Iowa, Iowa City, says in an essay in this week’s issue of Nature. In a 1995 paper, he and colleagues had trumpeted a two-tooth jaw from the Chinese site of Longgupo as the oldest hominin remains outside of Africa, dated to 1.8 million to 2 million years ago. But no longer. “In light of new evidence from across southeast Asia and after a decade of my own field research in Java, I have changed my mind,” Ciochon writes.

He now thinks the Longgupo specimen, as well as others—chiefly, isolated teeth—from similar Chinese sites belong to a “mystery ape” not on the hominin line. “I’ll probably get some grief from people about this,” Ciochon told me. “But it isn’t a hominid, and so I might as well say so.”

In part, the essay codifies current understanding. In his current papers, Ciochon had stopped referring to the Longgupo discovery, and in recent years few others had accepted the specimens as hominins. The Longgupo teeth are worn, making their identification “equivocal,” explains Ciochon. With additional, less-worn specimens from other localities, he is now convinced that this is a “mystery ape”—or apes—too fragmentary to be named.

“It’s great,” says paleoanthropologist Richard Potts of the Smithsonian Institution in Washington, D.C., after seeing the essay. “He’s backing off from Longgupo as a hominin, which a lot of us have been waiting for him to do.”

Ciochon’s real interest is not in the identity of the Longgupo teeth, however, but in the implications of the absence of hominids from that and other localities. He notes that the “mystery ape” sites are all located in what was once a subtropical forest, which also harbored a giant panda species, gibbons, orangutans, and the giant extinct ape Gigantopithecus. But the first hominin indisputably known in Asia, Homo erectus, is never found in such a subtropical forest environment. Instead, it turns up in more open, savanna-like habitat, like that of East Africa where early Homo evolved, says Ciochon. Longgupo and the other “mystery ape” sites sit in what was once a “vast and ecologically unattractive forest,” for hominins, Ciochon wrote in a recent commentary. He predicts hominid hunters didn't have much success in that environment. As he says in the essay:

H. erectus, it seems from this perspective, hunted grazing mammals on open grasslands, and did not or could not penetrate the dense subtropical forest. In fact, there is no record of early hominins living in tropical or subtropical forested environments in Africa or Asia.

But if the field welcomes the change in status of the Longgupo jaw, researchers such as Potts are not so sure about Ciochon’s paleoenvironmental scenario. Potts contends that East African hominids lived in a mosaic of open areas around swamps and lakes, with some shrubs, bushes, and distant forest. “The idea that Africa was a savanna and Homo erectus followed grasslands into Asia—that’s oversimplified from where we stand.”

Potts emphasizes that early hominids were adaptable. For him, the interesting question is not what was their favorite environment but how did they manage to survive in variable environments. Potts admits that there is “no compelling evidence” of hominids in the Asian subtropical forests in the Pleistocene, “but I wouldn’t rule it out.”

—Elizabeth Culotta

Illustration credit: Russell Ciochon/Nature