单选题 .  Beauty is a curious phenomenon, one of permeable, shifting boundaries. We may think we understand it,     21    we sense it effortlessly.     22    , it is a bundle of mysteries researchers are still     23    .
    Consider the ancient proverb:     24    is in the eye of the beholder. Until about 30 years ago it seemed too     25    for scientists to bother     26    . When they finally     27    it, their results     28    them.
        29    , the maxim is false. Facial beauty is the same     30    the world. In every tribe and culture, individuals will consider Sharon Stone, say, an attractive woman. It goes     31    . Males can identify good-looking men, and females alluring women. Old and young, rich and poor, learned and     32    , all agree     33    who is beautiful.     34    people of every class and personality type.
    We don't learn this response. We're born     35    it. In one recent study, babies just 20 hours old recognized attractive faces and     36    them. So beauty is in our DNA. The eye of the beholder doesn't matter.
    On the other hand, and this is     37    it gets     38    , the facial shell is just the foundation of beauty. We see the self in the face, every day,     39    and we can't     40    the two.21.