The biggest ever baby boom in ancient civilization began around 500 A.D. and lasted for about 800 years. That’s what the Washington State University anthropology professor Tim Kohler and his student Kelsey Reese have discovered. They reconstructed a model of the Neolithic Demographic Transition in the Southwestern United States. It’s the first time that researchers have prepared such a detailed population chart.

Baby Boom

Birth rate surpassed 1,000 a year during that baby boom

Kohler and Reese found that the Native American baby boom took place between 500 and 1300 A.D. During that period, annual birth rate  was around 1,000, and it continued to rise steadily. That’s much higher than the current U.S. population growth rate of 0.7% annually. People in that period had learned to store food they harvested. Their main dietary food was maize. To find out the details, researchers examined thousands of human remains such as stone tools.

The study was published in the Proceedings of the National Academy of Sciences. Researchers are of view that the birth rate during that period likely “exceeded the highest in the world today.” Neolithic farmers in the Four Corners region of Southwest started growing corn around 2000 B.C., but they only adopted corn after about 1600 years. By 400 B.C., corn accounted for 80% of the average person’s daily calorie intake.

People in southern Southwest had to limit baby boom

The baby boom started slowing around 1300 A.D. when the number of inhabitants plunged dramatically in northern Southwest. It could have been due to the drought that haunted the region in mid-1100s. Though the baby boom was rising at the time, the region was torn in conflicts. In mid-1200s, most people started leaving the area. Kohler attributed this to the population explosion. There was not sufficient food for everyone. Subsequently, the existing infrastructure collapsed as the few people who stayed behind were warding off intruders.

However, conditions in southern Southwest were quite different at this time. Population in this region was more restricted. People here were forced to limit the baby boom due to shortage of water, which was necessary for irrigation agricultural purposes.

Researchers said that the downfall of the ancient civilization could be a lesson for modern humans.