Why Don't Men Smile?

Have you ever noticed that men never smile? In photos they frown. When they approach others (specifically women) they always look unfriendly and unhappy. Men always tell women to smile. Women are beautiful and should look good and happy right? Well this is because men like to look at women in an objective way, which in a way is just fine, but what about the women? It personally doesn't bother me when I am told or asked to smile by a man. I don't really smile or feel offended,when I'm asked or told to smile because half the time I'm just too confused to react fast enough, but its just the hypocrisy. Me personally wants to see men looking approachable attractive and nice/easy to talk to. Not so angry and serious all the time, like the man is some "high God overlord" or the king over a kingdom. When a man doesn't smile or look happy it makes me want to run away or avoid eye contact. The anger that they have on their faces kinda rubs off on all the people around them, including me, and makes the atmosphere just change for the worst (make others uncomfortable if you will)