All animals, including the human species, instinctively tend to lick their wounds.
Until recently, biologists were unaware of the scientific basis for this behavior, although they suspected that the key was in some component of saliva . Last year pharmacologist Nigel Benjamin of the Royal London School of Medicine and Dentistry in London came across it: nitric oxide . Benjamin invited 14 volunteers to lick their palms and the back of their hands to collect saliva samples. In all of them, he found high levels of nitrite, a salt that turns into nitric oxide, a powerful bactericide.
