Question: what makes us human? and why do we yawn?

Martha Havenith answered on 21 Jun 2015:

Ha, let’s start with the easier part – no one knows why we yawn! People thought it was to get more oxygen into the brain, cool the head down… but those ideas have so far been shown to be wrong. So no one knows! Yet. Just goes to show there is a lot of science to be done still. One fun bit we do know about yawning: The fact that it’s ‘contagious’ seems to be down to empathy, so having an emotional bond to the person that’s yawning. This is one way you can detect psychopaths: they don’t tend to yawn when other people yawn. 🙂
Now, to the difficult bit: I’d say the thing that most makes us human is our ability to see ourselves as individual beings. A famous test for this is the ‘mirror test’. You secretly put a red dot on someone’s face, then put them in front of a mirror… if they touch their face to search for the red dot, they understand that they are looking at ‘themselves’. Some other species can pass that test too, for example apes and elephants. But it seems that humans have the greatest potential to become more and more aware of themselves (their thoughts, emotions, motivations, actions) and of the world around them, over the course of their life. So I’d say what truly makes us human is being uniquely stuck between reflexes, actions and emotions that animals have too, and a ‘higher’ awareness and ability to reflect on the world that we can reach. The really interesting challenge is to bring those two sides into harmony.