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A Journey to a New Land

Yesterday's Camels


For thousands and thousands of years, large animals like mammoths, lions, sabre tooth cats, and camels flourished in North America. They survived repeated ice ages as well as periods of warmer temperatures. But at the end of the last ice age, about 11,000 - 10,000 years ago, almost all of the large ice age animals suddenly became extinct.

What caused this mass extinction? Scientists have proposed at least two hypotheses to explain it:

  • 1. The Human Overkill Hypothesis
    Some scientists believe that human hunting was the cause of the extinction. When humans arrived in North America, they brought with them tools and hunting skills that enabled them to successfully hunt and kill large grazing animals. These animals were not used to being hunted by humans, so they had no natural defences and were easy prey. As the populations of large grazers declined, the animals that preyed upon them were also affected and their populations began to dwindle as well. Hunting success led to larger human populations and hence more hunting, and eventually all of the large animals became extinct.
  • 2. Climate Change Hypothesis
    Other scientists think that the warming climate at the end of the ice age was responsible for the extinction. As the climate warmed, the habitat of the large animals rapidly disappeared. Forests began to replace the grasslands on which these animals grazed. The cold-climate plants they liked to eat were replaced by new types of plants which they may not have been able to eat. As their grazing lands disappeared, smaller and smaller populations could be supported. The predators, again, would have had less to eat as the populations of grazing animals decreased.

There are other possible reasons for the extinction. Some scientists have suggested that a rapidly spreading disease may have been responsible. Or perhaps the extinction occurred because of a combination of all these factors.