 He says that's because we've evolved. The traits people commonly see as attractive are often related to being healthy. Okay, so just trying to get through this. The idea is there are attractive people linked with attractive people. Of course, attractiveness is subjective, but they're studying people here who see themselves as attractive and are seen as attractive. Many of us could probably think of a couple to whom this rule doesn't apply, so how did they end up together? Webster says we notice them because they are exceptions.