What is the number of close friends and acquaintances you have in your social circle? For some people, it might be a count-on-one-hand list, for some others, it might be a large number. The average human being, according to experts, is capable of maintaining stable, social relationships with 150 people, which is known as Dunbar’s Number. What Is It? Dunbar’s Number is a concept developed by British anthropologist Robin Dunbar. It is the number of social relationships that the average person is capable of developing and maintaining throughout their life. Dunbar developed this theory while studying the relationship between the brain size of primates