The First Americans, Part 1
Forseveral decades, archaeologists thought the first Americans were the Clovispeople, said to have reached the New World 13,000 years ago from northern Asiaby following Mammoths and other large prey across the Beringia Bridge. Supposedly,they journeyed rapidly overland from the Yukon to Alberta, leaving behind theirdistinctive stone tools across what is now the lower 48 states. But it has nowbeen established that humans reached the Americas thousands of years earlier.The evidence comes not only from archaeological finds, but also from geneticsand geology.
Forinstance, from a Texas creek bank, excavators discovered more than 19,000artifacts, some no larger than a thumbnail. One such artifact was once part ofan all-purpose cutting tool, like an ice age equivalent of a box cutter.Artifacts like these are pushing the history of humans in the New World backbeyond the Clovis people, since these tools were dated to 15,500 years ago.
Insouthern Chile, archaeologists found traces of early Americans who slept inhide-covered tents and ate seafood and wild potatoes 14,600 years ago. That waslong before the Clovis people appeared in North America. in Paisley Five MilePoint Caves in Oregon, another team found 14,400-year-old human fecescontaining seeds of desert parsley and other plants.
Over thepast decade, geneticists have been finding new clues where the first Americanscame from and when they left home by studying the DNA of indigenous peoples.This information strongly indicates the first Americans' ancestors came fromsouthern Siberia. Although this confirmed the suspected homeland, it alsoindicated that the New World colonists left their homeland between 25,000 and25,000 years ago. This would have been a difficult time to migrate, for hugeglaciers capped the mountain valleys of Asia, and massive ice sheets mantledmost of Canada, New England and several northern states. But that didn'tnecessarily stop the colonists.
The icesheets had lowered sea level by more than 100 meters, exposing continentalshelves. The newly revealed land of northeastern Asia and Alaska, plus adjacentregions in Siberia, Alaska and northern Canada, formed a landmass joining theOld World to the New known as Beringia.
The airthat swept over Beringia were dry and brought little snow to the area, thuspreventing the growth of ice sheets. It was an arid tundra grassland inhabitedby woolly mammoths, giant ground sloths, steppe bison, musk ox and caribou.Genetic studies suggest that sea lions likely inhabited the rocky islands thatstudded Beringia's south shore. So human migrants had their pick of hunting terrestrialmammals or seafaring ones.
The majorgenetic lineages of Natives Americans suggests that the earliest Americanspaused somewhere and evolved in isolation for thousands of years beforecontinuing on. Some 19,000 years ago, North America's ice sheets beganshrinking, creating 2 passable routes to the south. Several studies of thegeographical distribution of genetic diversity in indigenous Americans indicatethe earliest colonists arrived between 18,000 and 15,000 years ago, whichplaces them a pre-Clovis.
