About 10,000 years ago, the climate changed again, becoming warmer and drier. Since the huge animals they had hunted died out, the Paleo-Indians adapted and, using smaller spears and bows and arrows, began to hunt smaller animals. Some of the people began to live on shellfish, to weave nets to catch fish, to dig roots, and to gather berries, nuts, fruits, and grass seeds.
About 5,000 years ago, agriculture began in the Americas when the people in what is now Mexico began to plant the seeds of wild corn. Through "cultural diffusion," Indians in the Americas learned from each other and spread their knowledge further. The development of agriculture meant that the Indians could maintain a more stable food source and food supplies, could have more leisure time to develop the arts, and could settle down in more complex communities to "colonize" the Americas. [more]