@roger,
Quote:Whether happiness and smiling are the same might be a totally different question.
Indeed. I believe smiling develops in babies as a social thing; when babies smile we smile back; this is true of older children and adults. The fact that someone is smiling or not is a very poor indicator of their state of happiness.
In some cultures people smile when they are embarrassed; it would be ridiculous to ask if a small baby feels embarrassed.