As the glaciers disappeared and the climate became warmer, the lakes, swamps, and lagoons gradually dried up, the grasslands became desiccated, the hardwoods disappeared from the valley bottoms. Small regional differences in climate, sometimes due to altitude, left some areas more desirable than others. Large mammals disappeared entirely, and the hunting and gathering people had to turn to smaller types of game such as elk, deer, rabbit, bear, and rodents. No doubt wild edible plants, berries, fruits, nuts, and even roots were gathered and eaten. In the Four Corners country, however, evidence for occupation by man during the Altithermal (or second post-glacial period) is almost entirely lacking. This was an exceptionally dry period, and few if any people could live there. It wasn’t until the climate became wetter and cooler again, more like it is today, that man once again inhabited the Four Corners area in any great numbers. THE BASKETMAKERS. About the time of Christ, in some parts perhaps even earlier, small bands of Indians entered the Four Corners country. It is possible that a few small groups of wandering hunters and gatherers who had survived the Altithermal were already living there, but the archeological evidence for their presence is very scanty. Under the impetus of new ideas, such as agriculture, these people may have been slowly settling down to become farmers. Or possibly under the pressure of expanding populations elsewhere, groups seeking new lands suitable for agriculture moved into the area and either amalgamated with, or drove out, any local groups. If so, we do not know exactly where these people came from. Perhaps they came from the south, around the Mogollon Rim country of New Mexico where there is evidence that even earlier an agriculturally-based sedentary population had developed. Corn had been known in parts of the Southwest for a considerable time. (At Bat Cave in New Mexico, archeologists have uncovered a primitive type of corn which was grown at least several thousand years before the birth of Christ.) Only with an assured food supply, part of which can be stored against bad years, can a group find time to devote its energies to the arts and to the development of greater skill in crafts. The idea of agriculture must have spread slowly, for it forced a radical change in the living habits of those who practiced it, compared to their old subsistence pattern of hunting and gathering. At first, the hunting group would regard this new plant as just another seed crop—to be gathered when it was ripe. They dumped the seed in the ground and went on about their business; when it ripened they returned to harvest the crop, much as they went each year to harvest the pinyon crop when it was ripe.