SCIENCE WORLD REPORT : OLDEST BABY BOOM IN AMERICA - NATIVE AMERICAN POPULATION
EXCERPT:
The researchers looked at a century's worth of data on thousands of human remains found at hundreds of sites across the Four Corners region of the Southwest. After studying these remains and the sites where they were located, the scientists were able to create a detailed chronology of the area's transition from a hunter-gatherer society to a farming society; stone tools revealed a transition from cutting meat to pounding grain.
Maize, or corn, was actually grown in the area as early as 2000 BC; yet it seems as if the people in the region were slow to respond. By 400 BC, though, corn provided about 80 percent of the area's calories. These new farming practices cause populations numbers to rise steadily until about 500 AD. Around 900 AD, populations remained high, but birth rates began to fluctuate. Then in the mid-1100s, one of the largest known droughts in the Southwest occurred. Spurred by this drought and other reasons, from the mid-1000s to 1280, conflicts raged across the northern Southwest.
While there were as many as 40,000 people in the Southwest in the mid-1200s, within 30 years it was empty.
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I've toured this area of the South West and have also taken a college level class on Native Americans of California and the South West. My professor has said that usually people who've been said to have "disappeared" have actually responded to situations like this by joining another tribe, often as the lowest class of people in that tribe.