By Blake Edgar
The story used to be simple. Some 12,000 years ago, bands of hunters from Asia pursuing mammoth and other big game crossed an arctic land bridge to become the first Americans.
These so-called Clovis people fanned out over the years across a vast New World, establishing homes from Alaska to the tip of South America.
These days, though, the story has become much more complicated. New discoveries in recent years have added some strange plot twists, and answers to all the big questions regarding the first Americans - who, when, where, how, how often, and why - appear to be up for grabs.
Scientists at two meetings this month in California and New Mexico are mulling over the implications of recently discovered or restudied ancient skeletons and artifacts. Also being assessed is better information from more precise dating techniques and studies of the ancient Bering land-bridge environment as well as genetic patterns and native languages.
"I just think it's going to be much more complex than we've thought in the past," says Smithsonian Institution archaeologist Dennis Stanford. He believes that early Americans arrived at different times, from different places, and by different means - on foot, in boats, maybe even by dogsled.
Figuring out where the first immigrants came from has been stymied somewhat by confounding interpretations of ancient skeletal remains. The earliest North American finds, such as Nevada's Spirit Cave Man, have long, narrow braincases and short, narrow faces quite distinct from modern American Indians, leading to claims of South Pacific or even European ancestry for these immigrants. The oldest South American skulls, such as Brazil's Luzia, bear equally distinctive anatomy, which resembles instead modern Africans and Australians.
Maybe America was always a melting pot, luring people from afar. The bulk of anatomical, genetic and linguistic evidence, though, now indicates that the wide range of skull shapes uncovered so far means the first immigrants came from a diverse population originating somewhere in Asia.
The most direct route of these early pioneers would have been across the north Pacific. Rising seas from melting glaciers did not completely cover a land bridge between Siberia and Alaska until about 11,000 years ago, so plants, animals and people had time to cross an ice-free passage.
Bering pedestrians likely contended with giant short-faced bears and packs of hyenas. Paleoecologist Scott Elias pictures a milewide corridor flanked by huge ice sheets spewing muddy water. Underfoot lay endless moist, shrubby, wind-whipped tundra - tough going for two-legged travelers. There were few plants to burn for cooking fires and heat, and even fewer to eat for people or the animals they hunted.
Still, a Beringian crossing before 12,000 years ago flies in the face of conventional "Clovis" wisdom. Named for an ancient settlement in New Mexico, Clovis tools, including distinctive spear points, have long been considered the Americas' oldest technology. Many Clovis sites occur across the contiguous United States, all estimated at about 11,000 years old.
Over the years, scores of older candidates have been excavated and championed, but critics consistently discredit them. Except for Monte Verde.
A battery of radiocarbon dates puts people at this creekside campsite in south-central Chile around 12,500 years ago. When found, the site was covered with peat, preserving stone tools, animal bones, wood planks and stakes from long tents, fireplace ash, a human footprint and remains of over 70 kinds of edible plants.
Most archaeologists and anthropologists have come to accept that Monte Verde is older than Clovis sites by at least 1,000 years. Says Southern Methodist University archaeologist David Meltzer, "I think it's clear they came over a lot earlier."
How much earlier, however, is anyone's guess.
Blake Edgar, an editor of California Wild magazine, writes often about fossils and ancient cultures. He is co-author of the book From Lucy to Language, and he edited the new Discovery Travel Adventures guidebook Dinosaur Digs.
Copyright © 1999 Discovery Communications Inc.