新托福听写训练 第5期（在线收听）

We've all heard the proverb “beauty is only skin-deep” meaning that the outward appearance is not a valuable way to judge a person's worth. But researchers studying why animals they are attracted to each other had found the opposite may be truth for animals. For them, a beautiful face and body are reasonably reliable indicators of underline quality and the experiments had shown that many species appear to look for at least one classic characteristic of beauty mainly symmetry. Now, according to this theory, a more selective partner in the pair usually the female seeks the maximum possible balance the left and right half of a potential male's body. For example, certain female birds first check to see if the male's left wing is the same length and shape of the right to get clues about the bird's health and strength. Now what other evidence do we have

of this kind of behavior? Well, in one experiment researchers put color bands on the legs of male finches. The female by farprefers males with same color on both legs over those that have a different color on each leg. Another experiment involving male elks indicates the importance of symmetry in the antlers. Asymmetric antlers of course often indicate that the male has lost a fight to another male antlers and he is therefore not the strongest.