Sports Many animals engage in play, but homo sapiens is the only animal to have invented sports. Since sports are an invention, a part of culture rather than an aspect of nature, all definitions of sports are somewhat arbitrary. Whether sports are a human universal found in every known culture or a phenomenon unique to modern society depends upon one's definition of sports. Men and women have always run, jumped, climbed, lifted, thrown, and wrestled, but they have not always performed these physical activities competitively. Although all literate societies seem to have contests of one sort or another in which men, and sometimes women, compete in displays and tests of physical skill and prowess, sports may be strictly defined as physical contests performed for their own sake and not for some ulterior end. According to this strict definition, neither Neolithic (新石器时代的) hunters nor contestants in religious ceremonies such as the ancient Olympic s were engaged in sports. Insistence on the stipulation that sports must be performed for their own sake means the paradoxical elimination of many activities which are usually thought of as sports, such as exercises done for the sake of cardiovascular fitness, races run to satisfy a physical education requirement, ball s played to earn a paycheck. Strict definition also means abandonment of the traditional usage in which 'sport', derived from Middle English disporter, refers to any lighthearted recreational activity. In the minds of some 18th-century aristocrats, a of backgammon (15子游戏) and the seduction of a milkmaid were both considered good sport, but this usage of the term has become archaic. Strict conceptualization allows the construction of an evolutionary history of sports in which extrinsic political, economic, military, and religious motivations decrease in importance as intrinsic motivations—participation for its own sake—increase. The disadvantage, however, is that the determination that a given activity is truly a sport depends on the answer to a psychological question: What is the motivation of the participants? The question of motivation cannot be answered unambiguously. It is probable that the contestants of the ancient Olympic s were motivated by the intrinsic pleasure of the contest as well as by the religious imperatives of Greek cult. It is also probable that modern professional athletes are motivated by more than simply economic motives. Thus most scholars assume quietly that popular usage cannot be completely wrong to refer, for instance, to U. S. professional National Football League s as sports. The psychological aspects of sports are more difficult to assess because factors such as motivation are more difficult to measure than the size of audience or the amount of a contract. The psychological tests that have been administered have produced such a welter of contradictory results that many specialists are ready to abandon the attempt to pinpoint motives. Some generalizations, however, seem tenable. On the whole, physical fitness and the desire for relaxation seem to motivate those who shun competitive sports in favour of noncompetitive physical activities such as jogging, hiking, recreational swimming, and aerobics (although the development of aerobics contests testifies to the protean (变化多端的) nature of the competitive urge). Important to those who choose sports is the challenge of the contest, the opportunity to test one's physical and mental skills against another person, against nature, or against the abstraction of the sports record. The choice of one sport over another depends on the cultural availability of the sport (few Laotians play baseball), on social group (few truck drivers own polo ponies), on gender (women are not supposed to box), and on individual temperament (some people cannot enjoy golf). There is reason to believe that the distinction between team sports, which emphasize co