要約問題/1985年

次の文を読み、その要旨を９０字から１１０字の日本文で書け。ただし、句読点も字数に数える。

　All animals are playing a potentially very dangerous game with their environment, a game in which they must make decisions for which the reward is survival and the penalty for a mistake is discomfort or even death. In this game, however, fair play is not to be expected; for, the fact is, it is always rigged in one way or another, and all species cheat in some way.
　Let us consider two extreme cases: first, our own species as an example of an animal in which responses are almost wholly determined by individual experience. I have a small son. The fact that he has survived to the age of two is largely due to considerable care on the part of his normally untidy parents. Since he happened to us, we have learned to clear up. We hide saws and chisels; we lay ladders flat instead of leaving them propped against things; and we shut the garden gate. In short, the boy's opportunities for experiment are kept within limits, so that while he is free to learn by experience, we can be fairly sure that he is not going to hurt himself really badly. As he learns more about the world, we can relax the limits. It is generally accepted that the full treatment takes about twenty years... so we have another eighteen years to go.
　This is one way of rigging the survival game. The other extreme way is to have the right answers to all potentially disastrous experiments fitted in at the outset. For example, any sea anemone knows what is edible and what is not. It will grasp food with its tentacles and cram it into its mouth. It will reject inedible objects and close up when poked. A sea anemone does not learn to do these things; these responses are built in from the outset and they are unaltered by individual experience. You cannot teach anything to a sea anemone; it just does not learn.
　（注）　chisel:（大工道具の）のみ
　　　　　edible: fit to be eaten
　　　　　rig: arrange（an event,etc.）dishonestly for one's own advantage
　　　　　sea anemone:イソギンチャク
　　　　　tentacle:触手