听力原文： Men usually think the cartoon is funny. Women do not. And there's a good reason for the difference in opinion. We start finding things laughable or not laughable-early in life. And infant first smiles at approximately eight days of age. Many psychologists feel this is his first sign of simple pleasure. At six months or less, the infant laughs to express complex pleasures- such as the sight of Mother's smiling face. Psychiatrist Martin says that the earlier an infant begins to smile and laugh, the more advanced is his development. Studies revealed that children who did not develop these responses 'developed some 'disease' in later life, or simply gave up and died.' (23)