You just cannot help comparing.
If you want to judge a quality such as its attractiveness, the only way to do it is by comparison. You find something similar and decide which is the most attractive. Unless you have a clear-cut, objective way of measuring what you have to judge, you simply have to seek out something with which to compare that which you are valuing.
Kenrick and Gutierres asked male college students to rate the photographs of a bunch of potential dates. Some of them were asked to do this just before watching an episode of Charlie’s Angels, and some were asked just after watching it. Those men who had not just watched Farrah Fawcett and Jacklyn Smith running around after a load of baddies rated the potential dates pretty much as any other men would.
However, those who had just watched those beautiful crime fighters with their perfect faces and immaculate hair now had higher standards. They couldn’t help but compare these new photos with the goddesses they had just been drooling over. The potential dates were therefore rated as much less attractive.
In the past we were not exposed to many different people. Hundreds of years ago, a person would only meet the few potential mates in his own or neighbouring villages. Even a hundred years ago people would only see their few acquaintances plus a few grainy photos in newspapers and magazines. Then along came TV and we were exposed to many more beauties, beginning to distort our view of how attractive the average person is. And then came airbrushing, and the internet. Now everywhere we look we are exposed to impossible perfection. We may no longer be happy with what we have because our view of average has been skewed by this exposure.