It unnerved us that the aliens giggled at pain (not that all humans share the same emotional reactions either). The beings cried when we would have laughed, smiled where we'd normally frown, danced at funerals, rubbed their head when food was delicious, pointed to their feet when they were sick. Gradually, their population increased, they contributed more and more to our economy, and they bred with us (and us with them, quite willingly). As you’d imagine, our movies shifted, along with our stand-up comedy, our literature, our music. Eventually we wondered: Which of us had our signals mixed up?