It's certainly not universally viewed as acceptable intimacy by all cultures. Even more certainly, it's not viewed as acceptable intimacy in public. In some cultures, you're about as likely to see a couple kiss in public as you are to see them have sex in public.<p>> Similarly, the authors state that “no ethnographer working with Sub-Saharan African, New Guinea, or Amazonian foragers or horticulturalists reported having witnessed any occasion in which their study populations engaged in a romantic–sexual kiss”<p>That doesn't mean they don't kiss, of course. Consider that an ethnographer studying people in Tehran would probably conclude their society simply doesn't have homosexual behaviour. If nothing else, I would imagine that, like with other forms of intimacy often viewed as deviant (for example, anal or oral sex), clever people frequently rediscover it, and some like it, and then practice it, even if in secret.