2500 years ago, Hippocrates, an ancient Greek doctor, believed that there were four rivers in the human body, which were between fast and slow. Which river has the upper hand, this person has the elegance of this river. Rivers are characterized by differences in flow and liquid. If a person has a large proportion of yellow bile, this person is violent and powerful; If the proportion of blood in the body is large, this person is flexible; If the proportion of mucus in the body is large, this person is slow to stabilize; If the proportion of black bile in the body is large, this person is weak and cautious. These four temperament types are named as choleric, sanguine, mucinous and depressive respectively. Although these four kinds of people have been scientifically proved to have nothing to do with Hippocrates' four imaginary body fluids, the name is still used.

190 1 year, Karl Landsteiner of the University of Vienna discovered different types of blood and established ABO system, which solved the obstacles in the process of blood transfusion. This inspired Japanese psychologist Takeji Furukawa. 1927 Takeji Furukawa sensitively associated four blood types with four temperament types. On the basis of a lot of investigation, he thinks that the four temperament types of Hippocrates are not determined by bile and mucus, but by blood type. He combined the ABO system of South Desina with four temperament types, and founded the "temperament blood group theory".

Takeji Furukawa's research has aroused many people's interest, because it involves many unknown fields of anthropology and has made a great breakthrough in understanding human beings. In this way, the theory of body fluid has made new progress. Japanese blood group anthropologists can see that the true meaning of blood group refers to the constitution and temperament type of human body. "Blood type can be more simply defined as: blood type is the physique type and temperament type of all living things." However, many scholars believe that this theory has little scientific basis. Therefore, the relationship between temperament and blood type is controversial and needs further study.