Question: What is the point in humans smiling?

Bridget Waller answered on 17 Jun 2010:

Great question. 🙂

Smiling seems to be related to a similar expression in other primates called a bared-teeth display. Other primates use this as a signal of submission, fear or peaceful intentions, and when they use it, it prevents arguments from breaking out. So, we think that human smiling has a similar function. We smile at each other to show that we don’t want to fight, and so we can cooperate and live together without arguments. This was probably very important throughout evolution, as living in groups with others can be very difficult!!

Here is a link to some info on a paper I wrote about this recently:

http://news.sciencemag.org/sciencenow/2010/05/scienceshot-sympathy-from-the-de.html