Thousands of years ago, ten of our very distant ancestors were hungry. They went out and picked berries or dug up roots to eat. Four of them chose poisonous food and died. The remaining six noticed that their food was safe to eat. They told their children, who, in turn, passed the message on to their descendants. In this way, habit became a vital factor in the survival of mankind : if you ate the right plant, you lived if you wanted to make your own experiments, you would probably die. The importance of habit on the survival of the human species is an interesting matter. Even today, most of us hesitate when we are invited to eat a new type of food or drink something we have not tasted before. Even if the food or drink is offered by a friend, we are usually not at all anxious to experiment and accept the offer. When you get up tomorrow morning, notice which shoe or sock you put on first. Then notice which one you put on first on other days. You may discover that (a) you tend to put on one shoe or sock first every day, and that (b) if you are right-handed, you usually deal with your left shoe or sock first. If you try to change this habit, you may find it uncomfortable or annoying, and you will soon return to your old habit. When it comes to other matters, we often follow a fixed pattern. We sleep in one or two favorite ways. We often follow familiar routes even when they are not the shortest or best. We often wear a watch on the same wrist even when there is no real reason for doing so. (83)In hundreds of other ways, we show that we are creatures of habit, following fixed patterns of behavior. This characteristic can help us to survive but it can be a barrier to progress too. We must be alert and not let a beneficial factor become a harmful one. The best title for this passage might be _____.