Sporting activities are essentially modified forms of hunting behavior．Viewed biologically, the modern foot-bailer is in reality a member of a hunting group．His killing weapon has turned into a harmless football and his prey(猎物) into a goalmouth．If his aim is accurate and he scores a goal, he enjoys the hunter's triumph of killing his prey.
To understand how this transformation has taken place we must briefly look back at our forefathers．They spent over a million years evolving as cooperative hunters．Their very survival depended on success in the hunting-field．Under this pressure their whole way of life, even their bodies, became greatly changed．They became chasers, runners, jumpers, aimers, throwers and prey-killers．They cooperated as skillful male-group attackers.
Then about ten thousand years ago, after this immensely long period of hunting their food, they became farmers．Their improved intelce, so vital to their old hunting life, was put to a new use—that of controlling and domesticating their prey．The hunt became suddenly out of date．The food was there on the farms, awaiting their needs．The risks and uncertainties of the hunt were no longer essential for survival.
The author believes that sporting activities ______.