Kissing Works Best With Two People
A kiss is a sign of affection that 90% of people on this planet have enjoyed. A kiss can signal "welcome", "goodbye" and many variations of "I'm really glad to be close to you". A kiss shared between two people generally signals a desire for more of each other's smell, taste, and feel. Research has shown that women are stimulated faster by kissing than any other physical activity before engaging in sex.
Couple kissing.It is interesting to recognize that humans are the only species with lips that are turned outside the mouth. What we see as human lips are really part of the inside mouth. No other animals have this much lip exposed. This characteristic in humans, especially in female humans, apparently has evolved through preferential selection for this feature.
Lipstick.Full lips are one of the female features emphasized with makeup and even injections of silicone or one's own fat from other places on the body. Women know that men unconsciously recognize full lips as a sexual signal. The more sexual hormones a woman has, the more full her lips are.
Couple kissing.Lips in both men and women swell with additional blood when they become aroused. (As well as other body parts!) As men and women age, their lips become thinner because their sexual hormones decrease in later years.
Couple biting. Various mouth gestures also show affection and desire, such as nuzzling, licking, playful biting and so on. These actions can pleasure the senses by the release of endorphins in the brain that bring two people emotionally closer. Touch, taste and smell sensory nerves are all working to feed pleasure signals to the brain from numerous parts of the body. The lips and tongue have an exceptionally large number of nerves compared to most other areas on the body. The whole body becomes more sensitive. As pheromones are picked up from the partner's skin and hair, strong signals shoot to the old brain limbic system where hormones are released preparing the body for mating and at least temporary bonding.