ZHOUKOUDIAN, China — It's a mystery that has baffled the world for more than half a century. Whatever happened to the fossils of the prehistoric human ancestor known as Peking Man?
Their discovery in the late 1920s and 1930s in limestone caves on the outskirts of Beijing, the Chinese capital then called Peking in the West, was one of the greatest paleontological finds of the 20th century. The discovery was not the first of its kind, but it was the first and largest group of fossils of this ancient human found in China and established the hominid as a step in evolutionary history.
The fossils, believed to be 250,000 to 500,000 years old, included skull fragments, five almost complete skulls and other bones -- the remains of more than 40 individuals. Before more study could be done on the specimens, they disappeared amid a backdrop of war and intrigue.
Many have tried to track down the fossils, among them scientists, philanthropists, farmers and swindlers, as well as several governments. They might be hidden in China, the United States or Japan, lost at the bottom of an ocean, underneath an embassy garage or in a trunk among the belongings of a deceased person.
As time passed, even older fossils of early humans were found in Africa. The search for the missing evidence of Peking Man waned.
Then last year, the local government of the dusty suburb where the fossils were found decided to give it another go. A search committee was formed and a hot line established.
The new group sounds determined, despite long odds.
"We have to be confident and give it our all, even if there is only the slightest of hope," said Wang Zhimiao, a member of the committee, which works in an office on the hilly grounds of the Zhoukoudian Peking Man site.
Since China's economic boom helped boost its international standing and national confidence, the country has begun a quest to reclaim art and relics lost or stolen during decades of foreign domination and occupation. Zhoukoudian officials believe that finding the fossils will allow scientists to undertake additional study and help their community's image.
Calls for a new search arose among Chinese scholars in the late 1990s. Chinese journalists in 2000 published a manifesto linking the rediscovery of the fossils to restoring China's national pride.
"I don't know where they are. I believe they still exist," said Yang Haifeng, head of the search committee. "What belongs to us should be returned to us."
The committee's enthusiasm seems naive to those who have spent decades chasing dead ends.
"This is not a mystery," said Zhou Guoxing, 70, a paleoanthropologist who serves as an advisor to the committee and has devoted most of his life to looking for the fossils. "Somebody simply took it and hid it.
"It happened because of war and occupation," Zhou said. "This is an international problem. It's not something some district government committee is going to solve on its own."
Out by the cave where the fossils of the hairy, heavy-browed human ancestors were found, about a dozen staff members have been sifting through nearly 100 leads that have come in via phone calls, e-mails and letters.
A retired construction worker thinks the fossils are in Tianjin. He once worked at a U.S. military base there and said he saw Americans stash a box in a secret basement compartment before they fled China.
A former Chinese serviceman said they were in Taiwan. He said he saw a military plane fly to the Taiwanese city of Kaohsiung from Beijing during World War II and unload large crates that took three days to bury.
A farmer from Henan province said his grandfather long ago told him about a military truck buried in the middle of his village. It sounded so convincing that the committee recently took a team there and dug into the frozen soil for 10 days.
"We cannot dismiss any piece of information until we can prove it is not reliable," said Yang, the search committee head.
Western scientists first showed interest in Chinese fossils during the late 19th century. Decades later, a Swedish geologist, fascinated by a tooth believed to be 2 million years old in the collection of a German physician who had hunted fossils in China, began his own search in old Beijing. A local farmer led him to a cave in Zhoukoudian called Dragon Bone Hill.
In the late 1920s, an international team of paleontologists struck pay dirt in Zhoukoudian. A Chinese archeologist clinging to the side of the frigid cave by a rope, holding a hammer and a candle, saw a nearly complete human skull embedded in the rock.
Throughout the 1930s, additional evidence of early humans -- teeth, bones, jaws and more skull fragments, as well as stone tools and indications of the use of fire -- were found at the site.
But as scientists sought to build a more complete picture of how the early humans lived, war began. Japan invaded China in 1937 and all excavation ended.