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In the 1960s, Ethiopia's emperor watched with concern as a parade of anthropologists streamed into his nation's neighbor, Kenya.

During a 1966 state visit to Kenya, Haile Selassie, Ethiopia's leader, met with well-known anthropologist Louis Leakey, who had conducted groundbreaking field work in Kenya in pursuit of the oldest hominids.

Selassie asked why international anthropologists were avoiding his country's promising badlands. Leakey is said to have replied that running a recent expedition team out of the country at gunpoint didn't help matters, said John Fleagle, an anthropologist at Stony Brook University, part of the State University of New York system.

The next year, the emperor formally invited Leakey to organize what would become the International Omo Research Expedition and what would decades later put the African country at the forefront of studying the origins of human evolution.

Brushed aside: Leakey tapped his son, Richard, to organize the expedition, which included teams from the United States, France and Kenya.

Organizers split the area into three zones, one for each participating nation.

Richard Leakey, head of the Kenyan team, unearthed a pair of fossils that resembled modern humans. His team roughly dated the finds as 130,000 years old. But dreaming of fossils from millions of years ago, the researchers brushed aside the skulls and sent the remains to the National Museum of Ethiopia.

More than 30 years later, researchers from Utah, New York and Australia returned to the remote site with state-of-the-art equipment to date the rock layers that once held the skulls.

Their recent work, which appeared in the journal Nature last week, pushes the age of the skulls back to 195,000 years old. They now stand as the oldest known modern human fossils. The new fossils unseated the previous oldest known fossils, also from Ethiopia, by 30,000 years.

Before Leakey's team stumbled across the skull fragments, a young American grad student named Frank Brown was trekking around the area.

The American team sent the geology student ahead in 1966 to get the lay of the land. Brown spent a field season alone working out the stratigraphy of the local rocks, learning about the layers of rock laid down over the centuries.

After the rest of the team met with Brown in 1967, the researchers were invited to the Kenyan team's area to see the Leakey fossils. Older human relatives soon overshadowed the skulls found in the Kibish rock formation.

Return to Kibish: In the years after Selassie fell from power, anthropologists steered clear of Ethiopia and the Kibish area.

"It's extremely difficult to get there," said Australian geologist Ian McDougall. "It's one of the reasons people haven't gone back. Another reason is political turmoil."

The region's political situation had settled down by the late 1990s, opening up the possibility of heading back to the site.

Fleagle, the New York anthropologist, invited Brown to take another crack at Ethiopia.

A framed picture of Brown's grad student days in the sweltering Ethiopian badlands now sits in the waiting room next to his Salt Lake City office, where he serves as dean of the University of Utah College of Mines and Earth Sciences.

Sitting in his office with a recent visitor, Brown flipped through photos of the latest expedition he helped mount. One snapshot featured a rather sorry-looking rubber raft, which rats had chewed holes in, borrowed from a local missionary.

"We were putting tire patches and duct tape on to keep it afloat," he said of their transportation across a crocodile-laden river in 1999.

Getting to the site was only part of the challenge. Temperatures often soared above 100 degrees by 8 a.m., creating a sweat-through-your-clothes field work environment.

Ben Passey, a U. grad student on the expedition, said after a few days of that heat, he began missing refrigerators.

"There's no such thing as a cold drink out there," Passey said.

"Well, the river's cool," Brown offered.

Walking from the camp to the field site each day was like listening to a symphony as exotic bird calls filled the morning air, Passey said.

Once in a while, the river banks would come alive with sound, too. As one frog triggered a neighboring frog into letting loose a call, a string of croaks would crescendo as the noisy chain approached the listener.

Reconstructing history: Deeper into the field, the crumbling badlands consisted of layer after layer of deposited sediment. The Omo River used to drain into Lake Turkana around the area where the fossils were found.

Brown's task was to reconstruct the history of the area by testing the various layers.

The fossils, known as Omo I and Omo II, were found just above a volcanic deposit. New technology allowed McDougall, of the Australian National University, to test small pieces of feldspar to determine when the ash deposit was laid. Since the rock layers above the fossils had no datable material, the team had to guess the age based on the volcanic material below the fossil.

While studying the rocks and fossils, team members kept an eye out for scorpions and solfugids, fierce-looking, spiderlike creatures.

Researchers also knew that two rival tribes were usually somewhere nearby.

"They always knew where I was," he said. "I never knew where they were. I was more interested in the rocks."

The fossils sitting in these tribal areas demonstrate just how deep humanity's roots in Africa run.

"It shows our African heritage is much longer than anywhere else," Brown said of Homo sapiens as a species.

The trio of Ethiopian skulls - the two reported last week and the previously oldest one, reported in 2003 - now appear to come from the same time period. It may help give a better framework for human evolution.

These new fossil ages also renew questions about why it took so long for anatomically modern humans to develop modern human culture.

Evidence of needles, musical instruments and tools for eating only appears starting about 50,000 years ago.

Milford Wolpoff, an anthropologist at the University of Michigan, said the team did a good job on a problem that spent years gathering dust.

"Richard Leakey, who's nobody's fool, gave up on it," Wolpoff said.

The two skulls, despite observations that one looks more primitive than the other, could help give a more complete picture of the era with three skulls to compare from the same approximate time.

Though it took more than 30 years, Ethiopia's former emperor finally got his wish. Anthropologists now widely recognize the nation as a key place for understanding our origins.