Question: Why are humans so self-conscious? Why do so many people seem to care so much about what others think of them? And why do people judge others in the first place?

Susan Cartwright answered on 22 Jun 2015:

Basically, because we are strongly social animals, and it is essential to a society that its members contribute effectively to the society as a whole. Therefore, it has been important for millions of years that we know our place in the social hierarchy (i.e. that we care about what others think about us) and that members of the society who don’t contribute are recognised and dealt with (i.e people judge others). If you don’t know your place in your society, you may challenge a much more dominant individual and get hurt; if a society fails to recognise and deal with non-contributors, it will become loaded with lots of people who consume but don’t contribute, and may therefore fail in adverse conditions (a famine, bad weather, invasion of your territory by a rival tribe). So the ability to do these things gets favoured by evolution.

This works well in the kind of social groups it evolved in, i.e. small tribes of mostly related individuals. There is a number, called Dunbar’s number after the anthropologist Robin Dunbar, that describes the number of interpersonal relationships humans can handle – it’s about 100 to 300, depending on how you calculate it. So in a tribe of a couple of hundred individuals, everyone knows everyone else, and judgments about whether a particular individual is or is not contributing to the group are made on the basis of real knowledge.

It’s not so obvious that it works that well in modern urban societies, which are much larger. In this case, people tend to extend their judgments from individuals to entire groups (“immigrants”, “Muslims”, “black people”, “gays”) and make them on the basis of second-hand information (or, often, misinformation) rather than personal knowledge of an individual.

One of the most important characteristics of human beings is a thing called “theory of mind” – you can “put yourself in the place” of another individual and work out what he or she is likely to be thinking. For example, if you know that you have hidden something behind the sofa, and your brother was not there when you hid it, you do not expect your brother to know that there is something behind the sofa, because you know he wasn’t there when you hid it. This is something that develops gradually: very small children *would* expect their brother to look behind the sofa (*they* know there is something there, so they assume everyone else does too). It takes until about the age of 4 before children can reliably understand that what someone else knows about a situation is not the same as what they themselves know about it. One of the characteristics of autistic spectrum disorders is severe problems with theory of mind: autistic children typically expect that you will look behind the sofa at ages well beyond that at which neurologically normal children have realised that you won’t. Some people with schizophrenia also have issues with theory of mind.

It is believed that theory of mind is another evolutionary adaptation to effective team-work: if you and the rest of your tribe are hunting a mammoth, it is important that you understand what the other hunters do and don’t know, compared to what you know.

Most animals don’t seem to have theory of mind, though the evidence for chimpanzees is ambiguous.