When Did Humans Arrive In America?

Mar 27, 2011 By Deepa Gopal
Deepa Gopal's picture

When did humans first arrive in the Americas? History books talk about Clovis Indians, a nomadic hunter gatherer tribe and ancestors of present day American Indians, who lived 13,000 years ago.

A recent find at a site known as 'Buttermilk Creek', north of Austin, Texas has pushed that date back. A cache of stone tools found at the site has confirmed that the humans were around 15, 500 years ago, nearly 2,500 years earlier than originally thought.

A Land Bridge Appears

How did people cross over to the Americas? To answer the question, lets go back to the Ice Age - a time when glaciers covered much of the world, and wooly mammoths and saber toothed tigers roamed the plains. Ocean levels had gone down by as much as 300 feet. A strip of land appeared where there had been none before! The Bering Strait connected present day Siberia to Alaska, bridging the continents of Asia and North America.

A group of intrepid humans crossed into the New World chasing after mammoth and bison, and following an ice-free route, reached the plains of North America. They came to be known as Clovis Indians, after a city by the same name in New Mexico where the earliest stone tools were discovered. Since then, many other Clovis sites have been discovered across North and South America.

What set these people apart was the unique shape of their tools. Spears and knives were shaped like a leaf with a pointed tip. They were also fluted, meaning that they had grooves on either flat side. In Clovis, New Mexico, these tools were found with skeletal remains of young mammoths, proving that early hunters preyed on these animals near their watering holes. The Clovis Indians lived for nearly 500 years before they disappeared -- about the same time as mammoths and mastodons did! Did they hunt the animals to extinction and then die of starvation?

The New Evidence

Archeologists know how to precisely identify a Clovis site. But there was mounting evidence of people having existed earlier. Dried human waste found in a cave in Oregon had been dated to 14,000 years before the present. Similar evidence was coming from sites in Pennsylvania and as far off as Chile, South America. But there were problems in dating them that caused archeologists to doubt their results.

Usually archeologists use radio carbon dating, but there were no seeds or human remains in the Texas site. For the first time, the newly found quartz tools were dated by a technology known as optically stimulated luminescence -- it measures how long rocks like quartz have been out of sunlight. The small cache of stone tools were laid out neatly as if they were a mobile toolkit that the Paleo-Indians carried as they moved from place to place.

Who were these people? Did they follow the same path across the Bering Strait or did they come across from Europe on boats made of animal skins? Whatever the answer may be, our history books will certainly be re-written!