Blushing can definitely be a sign of physical attraction. Zoologist and author Desmond Morris believes that the reason that women started wearing blush on their cheeks in the first place was to represent the natural sexual flush. However, there are other reasons why we blush as well, and it should not, by itself, be taken as a definite indicator of attraction.
Physical causes of blushing
According to the NHS, blushing is caused by muscles in the blood vessels in the face that are controlled by the autonomic nervous system. The autonomic nervous system is not something that people consciously control. When the autonomic nervous system is overtaxed, it causes a slight swelling in these muscles and a slight reddening of the skin. There are many possible triggers for the autonomic nervous system, including emotional and physical stimuli. Some diseases, such as rosacea, can cause the long-term appearance of blushing. There is even a condition called erythrophobia, or the fear of blushing, which causes some individuals to blush even more in situations where they might blush.
Triggers for blushing
In addition to medical conditions and physical attraction, blushing can be triggered by a variety of strong emotions including guilt, anger or embarrassment. It can also be caused by excitement of a non-sexual nature. Beyond emotional triggers, heat, rapid changes in temperature, exercise and exertion can cause blushing. Certain foods can also trigger blushing. The list includes spicy foods, alcohol, hot drinks and anything that contains monosodium glutamate, or MSG, a common flavour enhancer in food.
Body language in women
The body language that signals female physical attraction can be quite subtle. Beyond blushing, prolonged eye contact is a frequent sign. Smiling is another common signal; it is meant to show interest and see if the interest is returned. Smiling is not always, of course, a sign of attraction. Preening is a more definite signal. When a woman does things like adjust her posture by sitting up straight to emphasise her breasts, play with or adjust her hair for a long period or straighten her clothing, she may be attracted to someone nearby. Touching is another definite sign. Light, casual touching, such as a hand on the arm or shoulder, is a test to check the man's comfort level with the contact.
Body language in men
Men are much less subtle than women when it comes to attraction. It is difficult for a man to hide physical attraction. For one thing, they tend to perspire more around women to whom they are attracted. Men will also use smiling, eye contact and tentative touching, but these are more pronounced in men. Men's primary body language comes from posture. Men do not preen in the same way women do, but posture definitely gives signs. A straight stance with the chest puffed out is typically a sign of attraction. Slouching, with the head down, is a sign of shyness, but does not necessarily indicate a lack of attraction. Crossing the arms is frequently meant to be a sign of assertiveness but is typically a sign of defensiveness.