The traditional scientific theory of the first Americans, known as the Clovis Model, proposed that humans migrated from Siberia to Alaska via the Bering Land Bridge around 13,000 years ago when sea levels dropped due to glaciation. These early humans, known as Clovis people, were big game hunters who spread throughout North America following the opening of an ice-free corridor through the Rocky Mountains around 11,500 years ago. However, evidence of pre-Clovis human occupation has challenged this long-held theory in recent decades.

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