#12 - JRL 7265
Financial Times (UK)
July 25, 2003
America's first immigrants
By Richard Stone
As elusive as the Cheshire Cat, the first people to arrive in the Americas have seemed to appear and vanish with each new twist in the archaeological record. The latest disappearing act takes place in the journal Science, where new evidence casts another shadow over a once-cherished idea: that Asian big-game hunters crossed the Bering land bridge between Siberia and Alaska to give rise to the Clovis people, considered the first Americans. New dating results show that a crucial Siberian site, thought to be a way station on the Bering road, was not occupied until after the Clovis had begun killing mammoths in North America.
The new finding "removes what was, until now, the critical link in the chain connecting Clovis to Siberia," says David Meltzer, an archaeologist at Southern Methodist University in Dallas. The paper "is really thought-provoking", adds Richard Potts, director of the human origins programme at the Smithsonian Institution's National Museum of Natural History (NMNH) in Washington. "Maybe it's time to consider less obvious sources for the oldest migration to the continent," he says.
Who the earliest Americans were and how they got there is anthropology's great riddle. The Clovis scattered their distinctively fluted projectile weapons across North America starting about 13,600 years ago - and then vanished several centuries later.
Their ancestors were thought to have crossed the land bridge that has at times linked present-day Alaska and north-eastern Siberia; the bridge appeared and disappeared with the fall and rise of sea level during the last ice age. But a handful of pre-Clovis sites, including one in Monte Verde, Chile, dated to about 15,000 years ago, have challenged this.
For researchers who believe the Clovis were truly the first Americans, the site of Ushki Lake on Russia's Kamchatka peninsula has been a critical piece of evidence. One of the few late ice age sites in north-eastern Asia, it was discovered in 1964 by Nikolai Dikov, a Siberian archaeologist, who ran a secretive dig for 25 years. "He rarely invited anyone out to the site apart from trusted colleagues and students," says Ted Goebel, palaeoanthropologist at the University of Nevada, Reno. But word began to filter out and in 1978 Mr Dikov, in his first English publication on Ushki, offered some brief but tantalising descriptions of what he had found.
One layer at the site, dated to 12,600 years ago, included wedge-shaped cores, tiny stone blades and burins - pointed tools for carving bone and antler. Beneath the floor of an earthen shelter, next to human bones, Mr Dikov also discovered a different collection of implements, including flaked cores, chipped bifacial points and stone beads that he called wampum. Most striking was the date: charcoal in the grave was dated to 16,800 years ago. If Mr Dikov was right, Ushki's earliest inhabitants, even though their stone points are shaped differently from those of the Clovis, might have provided one ancestral Clovis strand.
Wondering if the site had more secrets to reveal, Mr Goebel contacted Mr Dikov's widow, archaeologist Margarita Dikova of the North- east Asian Interdisciplinary Research Science Centre in Magadan, who agreed to a joint expedition in 2000. Joined by Michael Waters of Texas A&M University in College Station, they spent three weeks sampling and mapping the sediments at Ushki Lake. Mr Goebel came away with a new appreciation of Mr Dikov's work. "Everything he did was impeccable," he says. Everything except one thing: new analyses of charcoal fragments showed that the grave is only about 13,000 years old - six centuries later than the first Clovis points. "I was pretty shocked," says Mr Goebel.
Thus the Ushki Lake inhabitants themselves cannot be ancestors of the Clovis people. But, to Mr Goebel and his team, Ushki's dating facelift does not rule out Clovis origins in Beringia, the area around the Bering Strait. Mr Goebel notes that the most ancient known Beringians are those of the Nenana culture, who fashioned small biface points and knives; their oldest site, Broken Mammoth in central Alaska, is dated to 14,000 years ago, though no one is certain when or from where they reached Alaska.
It is possible, says Mr Goebel, that these Beringians raced down into the North American plains over a few centuries, developing into Clovis as they went - a sprint worthy of the Tour de France. "I do not see this as a dilemma," says Vance Haynes, geochronologist at the University of Arizona in Tucson.
Mr Haynes says recent dating suggests that the Clovis culture may be a few centuries younger, making the run from Alaska somewhat more plausible. According to Haynes, mammoths and other large animals encountered along the way would have required new hunting strategies and weapon designs that might have spurred the development of the Clovis point.
The other possibility, the authors say, is that there is no link between Clovis and the cultures of Ushki and Nenana - raising other possibilities for the peopling of the Americas. Some Bering enthusiasts favour an earlier migration across the land bridge - before the last glacial maximum 24,000 years ago - leaving plenty of time to reach Monte Verde. "I think with time we will find a link between Siberia and America, but it will be a much older link," Mr Waters says.
The newly discovered Yana rhinoceros horn site in northern Siberia, claimed to be 25,000 or more years old, may support this idea. Others disagree. "There's no evidence as yet in either Siberia or the Americas to support this," says Dennis Stanford, NMNH anthropologist.
With NMNH colleague Bruce Bradley, Mr Stanford is a proponent of multiple entry points for early Americans, including the once heretical idea of an ancient north Atlantic crossing. Mr Stanford notes that points and blades from a controversial site at Cactus Hill, Virginia, "show remarkable correspondence to Clovis" and may be 18,000 years old. The artifacts also closely resemble the Solutrean technology of northern Spain, from around that time.
"If artifacts resembling Solutrean were found in western Beringia most archaeologists would propose an ancestral relationship with Clovis," says Mr Stanford, who argues that "we must look outside of north-east Asia" for the origins of the earliest Americans. Mr Meltzer disagrees. Ushki's fall, he argues, "does not mean we should give up on Siberia and go looking for Clovis origins in all the wrong places" - meaning Europe.
Experts do agree that the archaeological record is too sparse to settle the debate. "This isn't a problem we can think our way out of," says Mr Meltzer, who urges increasing efforts in Siberia. "We need more early sites and data." The link between Clovis and Ushki Lake may be fading but, for many, the Siberian connection has not lost its Cheshire grin.
This article has been provided by AAAS and Science, its international journal