Nowhere is people's unshakable optimism better demonstrated. On the whole, there is a marked contrast between chemically and nervously determined functions. Nervous regulation, on the other hand, has tended toward flexibility, modifiability, choice of several courses of action. Rainfall varies in the United States from an average of 130.04 centimeters per year in South Atlantic states to 26.16 centimeters a year in the driest areas of the Southwest. Some communities have an almost constant shortage of water, and many others suffer from occasional drought.
Market weeks are trading periods observed by tribes that have developed a regular trade.
A market week may be from two to ten days long, varying in length among the different groups. During this period, trade and commerce take place at a particular location. The story is told that long ago in the animal kingdom every mother animal was trying to outdo the others by bragging about the number of babies she had. Finally, they all turned to the lioness who had only listened while they talked. Savage as have been the passions commonly causing war, and great as have been its horrors, it has, throughout the past, achieved certain immense benefits.