Let's say it clear, there are two main reasons why do we yawn: we usually yawn when we are bored or when we are tired. When you have to read another essay that makes you almost fall asleep, but you force yourself to finish it so you keep reading, and reading... I'm sure that at some point you start yawning. Or after a long day at work, when you have no more energy to call a pizza delivery place so you just sit on a couch doing nothing... You yawn a few times or more. But when we see someone yawning, we yawn too. Actually, sometimes thinking about it, forces us to do it, even if we are not neither bored nor tired. So why do we yawn then? And, is yawning contagious? Well, it definitely is and I'm sure you already know about it. But do you know why? It's a one of the common forms of echophenomena which is an automatic imitation of somebody's actions.  So, are you already yawning?

  You're preparing a family dinner: no meat and no onion for mum, but a lot of meat and a lot of onions for dad instead. Your brother is a seafood lover while your fianc é won't take a bite of anything that lives in the sea. Too complicated? Try to remember who likes olives, blue cheese, mushrooms and brussels sprout and who hates it, only to get to know that it's completely not true, because in the last few weeks everything has changed. Why do we like foods that we used to hate before? The main reason is, our taste buds regenerate. The scientists claim, it happens every two or three weeks until we celebrate our 40th birthday. Then the whole process slow down, and we don't notice the changes anymore.