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Why Is Yawning Contagious?: Everything You Ever Wanted to Know about the Human Body - And Some Things You'd Rather Not
Why Is Yawning Contagious Everything You Ever Wanted to Know about the Human Body - And Some Things You'd Rather Not Author:Francesca Gould Everything you ever wanted to know about the human body - and some things you'd rather not...A wonderfully entertaining yet authoritative treasure trove of facts about our anatomy - it answers all the questions about our bodies we're usually too embarrassed to ask.* Why is yawning contagious? Some experts think that yawning may have developed as... more » a means of communication. It may, for example, be a way of signalling to others that it's important to remain alert and stay awake in a certain situation. Another theory is that our early ancestors used it as part of their social behaviour, and as a way to help build a bond with the rest of the group.* Why are bogies green? When white blood cells meet germs, they make a large amount of an enzyme called myeloperoxidase, which is green because it contains a lot of iron. The colouration therefore comes from the iron.« less