The Utility of Rapid Coagulation in Preventing Loss of Blood
The increase of blood sugar, the secretion of adrenin, and the altered circulation in pain and emotional excitement have been interpreted in the foregoing discussion as biological adaptations to conditions in wild life which are likely to involve pain and emotional excitement, i. e., the necessities of fighting or flight. The more rapid clotting of blood under these same circumstances may also be regarded as an adaptive process, useful to the organism. The importance of conserving the blood, especially in the struggles of mortal combat, needs no argument. The effect of local injury in favoring the formation of a clot to seal the opened vessels is obviously adaptive in protecting the organism against hemorrhage. The injury that causes opening of blood vessels, however, is, if extensive, likely also to produce pain. And, as already shown, conditions producing pain increase adrenal secretion and hasten coagulation. Thus injury would be made less dangerous as an occasion for serious hemorrhage by two effects which the injury itself produces in the body—the local effect on clotting at the region of injury and the general effect on the speed of clotting wrought by reflex secretion of adrenin.
According to the argument here presented the strong emotions, as fear and anger, are rightly interpreted as the concomitants of bodily changes which may be of utmost service in subsequent action. These bodily changes are so much like those which occur in pain and fierce struggle that, as early writers on evolution suggested, the emotions may be considered as foreshadowing the suffering and intensity of actual strife. On this general basis, therefore, the bodily alterations attending violent emotional states would, as organic preparations for fighting and possible injury, naturally involve the effects which pain itself would produce. And increased blood sugar, increased adrenin, an adapted circulation and rapid clotting would all be favorable to the preservation of the organism that could best produce them.