The saying “a person with a big head must be smart” is wrong, because there is no necessary relationship between smartness and head size. The reason why the saying “people with big heads are smart” has been circulated may be related to the fact that many people believe that “the bigger the head, the more brain cells there are, and the smarter the person is”. But this is actually wrong. Scientific research has proved that the human brain consists of nerve cells and glial cells, and the level of intelligence is only related to the number, type and distribution of nerve cells, although the proportion of glial cells is very large, but the distribution has nothing to do with intelligence. As for the size of the head, that is, the circumference of the head, under normal circumstances, should be within the normal range, and if it is big or small, it is mostly related to diseases, such as hydrocephalus, malnutrition, etc., and should be actively seeking medical treatment.