A computer model was designed to determine how long it would have taken for a small group of hunters to spread across North America. | A computer model showed that it was possible for a small group of hunters to spread across North America and kill off game animals in just 300 years. | According to a computer model, people coming into North America 12,000 years ago had to kill game animals in order to feed their population. | According to a computer model, about 12,000 years ago conditions enabled a small group of hunters to enter and cross North America in about 300 years. |