BEIJING - After yielding Java Man and Peking Man earlier this century, East Asia almost dropped off the map for archaeologists searching for clues to human evolution.
But the region's recent period of peace and stability has allowed archaeologists to start digging again, turning up a series of discoveries that is forcing a fundamental reassessment of how humans evolved. Strands of evidence being gleaned from sites in China and Indonesia during the past two years now suggest that Asia played a bigger role than previously imagined - possibly even giving rise to modern humans, who were thought to have originated in Africa.
The newly unearthed evidence has led to a debate over when an early species of human, Homo erectus, migrated from Africa to Asia, with some archaeologists even hypothesizing that Homo erectus evolved in Asia and migrated to Africa. At the very least, many mainstream archaeologists believe that Homo erectus arrived in Asia much earlier than previously thought.
"The hot point in this field is: When did early man arrive in Asia?" says Sari Miller-Antonio, a paleoanthropologist from California who recently arrived at a dig in southern China. "Was it 1 million years ago or a lot earlier?"
Adds Russell Ciochon of the University of Iowa: "We are witnessing a fundamental shift in the paradigm. We are able to argue that hominids were in Asia by 1.9 million years ago."
For China, the new thinking in world archaeological circles confirms what its experts and cultural nationalists have long asserted: that humans evolved here much earlier than foreigners previously imagined and that human life may even have its roots in Asia and not Africa.
Long proud of China's thousands of years of cultural continuity, some in China are eager to show that it is also the cradle of humanity.
Government propaganda, for example, recently latched onto preliminary research to show that humans developed here first.
"For a long time, international anthropologists had believed that anthropoids originated in Africa, and later spread to other parts of the world," the government-run New China News Agency reported after the purported discovery in April of early rabbit-sized apes that lived in China 40 million years ago. "The finding suggests that the earliest humanlike or apelike creature first appeared in China rather than in Africa."
New discoveries in China do show that the standard view of human evolution may have to be revised so it is more in line with China's view.
Until now, the conventional wisdom has been that early humans, or hominids, evolved in Africa. For example, Homo habilis, the first toolmaker, is found only in Africa. This species evolved 2.5 million years ago into Homo erectus, who was thought to have left Africa about a million years ago after developing sophisticated tools.
The most famous examples of Homo erectus are Java and Peking men, who are estimated to be several hundred thousand years old. Eventually, Homo erectus was replaced by modern humans - Homo sapiens - about 150,000 years ago. Homo sapiens also may have migrated out of Africa.
The first hints of a shift away from this model came nearly 30 years ago, when U.S. researchers found a skull of Homo erectus in Indonesia. It was dated as 1.9 million years old, which was immediately rejected as impossible.
New dating techniques used in 1994, however, confirmed the date as accurate. Just as important have been new finds in China, especially in Longgupo Cave in central China. There, in findings published last year, Chinese and foreign researchers report they found part of an adult jaw and a tooth that are 1.9 million years old, according to three dating techniques.
Longgupo Cave is key because it backs up the Indonesian find, lending weight to the idea that early humans left Africa twice as early as previously believed. And it also hints that an earlier hominid may have been in Asia. The tooth found in the cave, it turns out, strongly resembles an incisor of Homo ergaster, a species in between Homo habilis and Homo erectus.
The significance would be that species even earlier than Homo erectus migrated to Asia and - to speculate even further - that these earlier hominids may have developed into Homo erectus in Asia and migrated to Africa, rather than the other way around.
From this, it's a short leap to arguing that Homo sapiens evolved independently in Asia instead of Africa.
A problem with overturning the conventional wisdom is that the evidence is fragmentary. Part of a jaw and a tooth - both of which could be from apes - is a slender thread to challenge orthodoxy, said archaeologist Deborah Bakken of the University of Illinois in Champaign-Urbana.
"It think it will take a bit more evidence before people are convinced," Bakken said. "We need one more good site."
Recently, a group of archaeologists arrived at what may be that next great site. Led by Huang Weiwen of the Academica Sinica's Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, the group of Chinese and U.S. scientists are digging at a large cave called Panxian Dadong in southern China's Guizhou province.
Last year, Huang found there what he believes is a hand ax used by Homo erectus. If accurate, Huang's discovery would show that Homo erectus used as sophisticated tools as his counterpart in Africa, bolstering the theory that Asia's Homo erectus was just as likely to have developed into Homo sapiens as Africa's version of the species.