The Clovis Theory

1. The Traditional Scientific Theory of the Origin of the First Americans
“The Clovis Model”
The Evolution of Humans
The Bering Land Bridge
The Ice-Free Corridor
The Clovis Barrier
Spreading through the Americas

2. The Evolution of Humans
• The theory of evolution is widely accepted by scientists, but many religions do
not accept the idea.
• Scientists believe humans evolved. Some early monkeys led to apes. One
group of apes evolved into humans
• Human evolution occurred in Africa
• Humans were hunters and gatherers - developing uniquely human
characteristics -
– walking on two feet
– tools
– language
– fire
– shelter and clothing

3. The Evolution of Humans - 2
• Four types of humans evolved
– Negroid in Africa
– Caucasoid in Europe and western Asia
– Australoid in Australia
– Mongoloid in eastern parts of Asia
• By about 50,000 years BP they were able to move out of tropics into coldest
areas of the earth - reached all through the Old World as far as Australia and
Siberia
• At this time scientists believe there were still no humans in the Americas

4. The Bering Land Bridge
• Scientists believe humans moved from Siberia into Alaska and the Yukon
perhaps as long ago as 40,000- 25,000 years BP
• They were able to cross on foot where the Bering Strait is today
– Sea levels went down as a result of the last ice age
– During the ice age the normal water cycle did not work
– Precipitation was frozen and trapped in huge glaciers or ice sheets
– The ice sheets were as thick as 3000 metres
– Sea levels went down as huge amounts of water were trapped in the ice
sheets
– the Bering Strait was above sea level - the land there has been called the
Bering Land Bridge or Beringia
– Beringia may have been 600 km wide from north to south

5. The Ice Free Corridor
• Scientists believe humans reached Alaska and the Yukon by at least 25,000
years BP by way of the Bering land Bridge
• These first Americans were big game hunters
• Scientists believe the ice sheets did not cover Alaska and the Yukon, but
covered almost all of the rest of North America south of the Yukon
• About 14,000 years ago the temperature of the earth began to warm
• 11,000 - 10,500 years BP the ice sheet on the Rocky Mountains separated
from the ice sheet over central Canada, and a corridor along the eastern side of
the Rockies opened
• Humans moved through the corridor into the southwestern parts of the United
States
• Humans then spread rapidly through the unglaciated parts of the Americas

6. The Corridor Opens
18,000 years ago | 14,000 years ago

7. 13,000 years ago | 12,000 years ago

8. 10,000 years ago | 9,000 years ago

9. 8,400 years ago | 8,000 years ago

10. 7000 Years Ago

11. 4. The Clovis Barrier
• Archaeologists found a spear point at Clovis in New Mexico
• It was the oldest clearly datable artifact made by humans - it dated to 10,500-
11,000 BP
• It was found in with bones of a mammoth, which became extinct 10,000 years
ago
• Clovis points were found widely through North America
• No earlier traces of human activity could be clearly proven before the Clovis
dates
• Evidence of human activity soon after this date is found all the way to the
southern tip of South America
• Evidence of human big game hunting traditions is widespread after the Clovis
dates
• Scientists believed (in the 1970s) that no humans entered the Americas before
the Clovis dates
• Evidence for any earlier human presence could not be found - the Clovis dates
were a barrier. Before this there was no clear evidence.

12. Clovis Points

13. A Clovis Point

14. 5. Spreading through the Americas
• The original big game hunters who entered the Americas south of the Yukon
moved rapidly through the new environment
• Many animals became extinct in the Americas soon after this
– mammoths
– mastodons
– horses
– camels (in North America)
– giant bison
• Human hunting may have been a factor, together with changes in environment
• Big game hunters moved into new environments, and adapted, finding new
ways to live
• Many new cultures arose in the new environments