Russell Ciochon has changed his mind about the identity of fossils found in Longgupo, China. Credit: J. W. ROGERS

An Essay on page 910 of this issue withdraws the conclusion of a 14-year-old Nature article (W. Huang et al. Nature 378, 275–278; 1995) describing what had been thought to be the oldest Homo fossil in Asia.

Anthropologist Russell Ciochon, of the University of Iowa in Iowa City, writes that he now thinks the jaw segment with two teeth, dated to about 1.9 million years ago from the Longgupo cave in Sichuan province, China, belongs to an ape. "We threw out a trial balloon" in 1995, he says. "Academics change their minds based on new evidence and with the passage of time."

At the time, some anthropologists had suggested that the jaw might in fact have been from an orangutan-like species (J. H. Schwartz and I. Tattersall Nature 381, 201–202; 1996). One of those, anthropologist Jeffrey Schwartz at the University of Pittsburgh in Pennsylvania, calls the Essay "really astonishing. It is not often that a scientist says he changes his mind. This openness is good."

The time at which Homo species first arrived in Asia has been a hotly contested subject; fossils of Homo erectus have been found dating to 1.6 million years ago in Java. The 1995 Nature paper implied that an earlier species, such as Homo habilis, was present in Asia earlier, at 1.9 million years ago.

The discovery of two apparent stone tools, the jaw and a tooth that is indisputably Homo — found in nearby sediments — stoked speculation that Homo erectus may have evolved outside of Africa. The nine authors concluded that early humans had entered Asia at roughly the same time as the genus Homo started to diversify in Africa. "Clearly, the first hominid to arrive in Asia was a species other than true H. erectus, and one that possessed a stone-based technology," they wrote.

Some anthropologists then working in China disputed this interpretation. "I never thought it was Homo, but akin to apes," says palaeoanthropologist Dennis Etler, now at Cabrillo College in Aptos, California. In 1998, Etler had convinced a co-author of the original paper, archaeologist Roy Larick, that the jaw wasn't Homo.

Ciochon says he changed his mind about four years ago after examining a tooth collection at the Guangxi Zhuang Natural History Museum in Nanning, China, including eight teeth that resemble the molars found at Longgupo. Late last year, he says, he proposed "a personal commentary" in Nature on the "problematic jaw".

Ciochon, the sole author of the resultant Essay, says he didn't discuss the piece with the original article's lead author and discoverer of the jaw, anthropologist Huang Wanpo of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, nor with co-author Gu Yumin, Huang's wife and an anthropologist. The other authors, other than Larick, weren't involved in analysing the jaw, Ciochon says.

Huang says that several scientists from around the world have long considered the jaw to be that of an ape.

Schwartz says he wants to see more details about the 'mystery ape'; Ciochon says he plans to publish those after more work with Wang Wei, director of the Nanning museum.