All social animals are affected by what others around them are doing. Even newborn chicks feed better if others around them are pecking. Human applications range from lifestyle competition on Facebook to looting mobs and irrational exuberance of markets.

The Automaticity of Behavioral Conformity

If you stand on a busy street and gaze intently into a shop window, you may find others stopping to investigate what you are looking at, or even collect a crowd.

Paying attention to what others are doing may be a feature of all social animals. English researchers noticed that after small birds mastered the job of piercing the foil cap of milk bottles delivered to doorsteps that other individuals began doing the same so that the pesky tradition spread. Clearly, it pays off for birds to notice how others get food. (Whether one calls this process social facilitation, or imitation, the practical consequences are the same).

Humans may not be quite so focused on food but we also pay close attention to what other people around us are doing. This is involuntary—a natural consequence of living in human societies—and it is as true of small familiar groups as large anonymous ones.

Social psychologists and other scholars have given a lot of attention to the question of whether and why we imitate others and what the practical consequences are.

Irrational Exuberance, Crowds, and Nazis

There is a strong tendency for people in public places to imitate what others around them are doing. If a car speeds through a pedestrian crossing on which several people are gathered ready to cross, it is a safe bet that following cars will do exactly the same. Likewise, if a person is lying unconscious on the ground, possibly in need of medical help, if people ahead of you are continuing on their way, you are likely to do the same.

Such situations have considerable uncertainty and we may take other people's actions as a cue to appropriate behavior (1). This principle is widely used by marketers who know that if we can be persuaded a product is popular that we will assume it is good.

Social conformity pressures can exert powerful control over us, whether it is chanting at a sports event or hurling rocks at police in a political protest.

The exuberance of crowds has been used to explain the strength of political movements, religious fanaticism, and investing bubbles such as the tulip mania in Holland, or the dotcom craze of 1999.

How can we begin to understand such irrationality from an evolutionary perspective.

The Evolutionary History of Conformity

Humans, specifically young children, are noticeably more inclined to imitate than other primates are. Children are said to over-imitate or copy the experimenter exactly even if some movements are superfluous to getting a task done (2). That means that even in early life, we are very good at taking our cues from others and fitting in with social expectations.

One key qualification is that not all societies are equally conformist. Foragers are more individualistic than members of agricultural societies (3). So religious fanaticism involving such extreme practices as human sacrifice by the Aztec Sun God religion came after the agricultural revolution (and centered around cultivation of corn).

One plausible explanation for this pattern is that agriculture permitted greater population density, and introduced a great deal of inequality between rulers and the ruled based on inherited wealth (such as grain stores). Such inequality may be inherently unstable in the absence of rigid conformity to social class expectations. Think of an Upstairs Downstairs episode in which the servants swore at their employers and told them to do their own laundry.

In modern social democracies, extreme inequality persists but those close to the bottom of the hierarchy do much better than slaves of the past. So we no longer have to conform to the requirements of a rigid class system and do not have to emulate others to the same degree. Yet, we continue to take our cue from others. Even as the poor aspire to the leisured lifestyle and dress of the affluent, the wealthy sometimes affect the torn denim of the working class.


1 Cialdini, R. (1988). Influence: Science and practice (2nd Ed.). Glenview, IL: Scott Foresman.

2 Henrich, J. (2015). The secret of our success: How culture is driving human evolution domesticating our species and making us smarter. Princeton, NJ: Princeton university Press.

3 Boehm, C. (2000). Hierarchy in the forest. Cambridge, MA; Harvard University Press.

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