All animals have distinctive body odours. Theses smells are important in giving other animals of our own and different species important information about our identity, emotional state (fear, anger, aggression, etc.), state of sexual arousal and health. Body odours are produced by sweat and other feromones, and are not normally offensive. Sweat is odourless when secreted and normally evaporates quickly. When sweat cannot evaporate because of climatic conditions or because it is trapped where air cannot circulate freely (armpits, groin, feet), an offensive smell can develop because of the action of normal skin bacteria which break down certain chemicals in sweat. Unpleasant perspiration smells can be prevented by washing regularly in hot, humid weather, by avoiding synthetic clothing which prevents the absorption and evaporation of sweat, and by the appropriate use of deodorants.
There are actually two kinds of sweat! one type is for cooling the body, or lubricating (like sweaty feet in a tight shoe) and the second type is a stress response sweat! it mixes and releases pheromones to let our nearby humans that danger is afoot!