Influence is not always accurate

Are we going to take this as fact, because a college professor says it's so? I'm not buying it.
He says that yawning is done to cool off the brain. He says the brain overheats and our body yawns to cool off the brain. He says one way to prevent it is to breath through the nose, because that cools off the brain.
He contradicts himself. If it's better to breath through your nose, why would the body naturally open your mouth and breath through the mouth?
I prefer to go with the old theory that it's due to the lack of oxygen. Take a deep breath (nose or mouth) and it helps.
If yawning is caused by brain heating, why would somebody start yawning when they are in the process of freezing to death?
Next I would like to know if my tax dollars paid for this research? THIS wakes ME up!!
I know you don't have to be smart to be on that show. Diane Sawyer thinks whales have gills. One short report on there, not a regular, but does reports for them, when they were talking about shoes, she said, "I don't like to wear flats, because they make me look shorter than I really am." Okay, how tall is she really? She must be like the blond, when asked how tall she was, replied, "I'm 5'10" in 3 inch heals."