In the reading passage, there is ample support for the author's claim that there are numerous hypotheses explaining why people yawn. However, the professor in the lecture gives several reasons as a rebuttal to the author's point.
First, the professor contends that yawning cannot be a possible way of communication with others. Considering where and how people yawn, communication cannot be the goal of yawning. This is because people also yawn when they are alone, and they are inclined to cover their mouth or suppress yawning when others are with them. This casts doubt on the reading passage's claim that yawning can convey information such as nervousness and stress without utilizing language to other people.
Next, the professor argues that an idea that yawning is used to make pressure inside and outside the ear equalized is implausible. If this is true, yawning should occur only when an altitude alters, which is in contradiction to the real observation. In effect, people yawn in all sorts of divergent situations. This refutes the reading passage's assertion that the muscles of ears contract and relax by yawning, which removes the difference between the air pressure of the inner part of the ear and that of the outside atmosphere.
Finally, the professor insists that yawning does not make people increase their alertness. It is known that people can fall asleep soon after yawning, so this does not avert the tiredness of them. In fact, yawning has a relaxing effect, because it stretches muscles in a human body. This counters the reading passage's suggestion that yawning results in more vibrant states of a body such as risen heart rate and blood pressure, which gives rise to more alert conditions.