Human success stems from our social groups. By working together we can achieve more than we ever could hope to individually. In fact, the benefits of group life are so profound that they’ve shaped the course of our biological evolution. Our large brains, for example, evolved in part to help us remember lots of people and relationships, allowing us to live in bigger and better groups.
Group life has also left its evolutionary mark on our psychology as well. Humans are very susceptible to peer pressure and the watchful eyes of others. This vulnerability to peer pressure is so strong that even cartoons of eyes watching us can make us less likely to cheat. In fact, images of eyes reduce the level of cheating even more than a strongly worded sign saying “don’t cheat.”
Carefully placed eyes can even reduce the rate at which people litter, increase the likelihood they’ll leave the correct amount of money for their purchases in an unsupervised shop and increase the rate at which they follow recycling rules. But what’s perhaps most interesting is that people in these experiments don’t report even noticing the eyes, or feeling under extra pressure. This is all going on at a subconscious level.
The eyes say “subscribe to EvoAnth”
In short, those who behaved correctly when being watched by other members of their group flourished as they weren’t being thrown out of groups for being nasty. This spread this trait throughout the population through natural selection until we all had an innate, subconscious response to seeing eyes, even if they were cartoon, that makes us more likely to follow the rules.
Chimps are our closest living relatives and also live in large complex groups. These groups also appear to have shaped their evolutionary history and so, like humans, they’re vulnerable to peer pressure and so are less likely to misbehave when being watched by others. For example, low ranking chimps are less likely to try and take food if being watched by others in their group.
But are they as susceptible to peer pressure as humans? Are images enough to make them follow the rules? To test this, scientists created a similar experiment to the ones used in humans. They presented a chimp with some peanuts that, by rights, should belong to the dominant male. They then either put up a picture of another chimp or a neutral image and watched to see if the chimps would take the food anyway.
Chimps were either presented with the face of another chimp (top), or the freaky muddled up face (bottom)
Unlike humans, chimps took the food in every test; even when shown an image of another chimps. Low ranking chimps tended to hesitate a bit when the face of another chimp was visible, but still ate the dominant male’s peanuts! Clearly chimpanzees are pure evil, the blankness of their fur matched only by the blackness of their hearts. It also indicates that, unlike in humans, their susceptibility to peer pressure is not strong enough for them to be influenced by mere images of rule enforcers (Nettle et al., 2013).
This means that they hyper-susceptibility seen in humans evolved at some point within the last 7 million years since we split from chimps. We can probably narrow this down to within the last 2 million years, as it’s only since then that our social groups have become larger and more complex than chimps (Dunbar, 1993).
Some may count it as a victory for those damn dirty apes that they’re capable of figuring out a picture isn’t real and thus can’t hurt them if they misbehave. On the other hand I can’t help wonder if the ease with which people can be bullied into behaving is one of the reasons our society has been so successful.
References
Dunbar, R. 1993. Coevolution of neocortical size, group size and language in humans. Behavioural and Brain Sciences, 16: 681-735
Nettle, D., Cronin, K. A., & Bateson, M. (2013). Responses of chimpanzees to cues of conspecific observation. Animal Behaviour.
EvoAnth 
I like your article – as always. You are doing great research and present well.
But anthropology is not psychology and you seem to have made a jump from the idea that if chimps don’t respond to pictures, they are not as vulnerable to peer pressure, without considering that people have been ‘programmed’ to work with images (in print, books, posters), while chimp societies live in a 3D world of objects. They simply know (better than we do) the difference between real and reproduction.
Besides that, not all types of people are equally vulnerable to peer pressure. Don’t forget that all those tests are done with random samples, which means they always represent only the types of people that are in the majority.
I wouldn’t phrase it as chimps being better at distinguishing between real and reproduction, but humans are perhaps more primed by our culture to pay attention to reproductions.
Despite the likelihood cultural component, the subconscious nature of people’s reactions to the eyes suggests there is something innate there. Whilst there’s obviously always room for further research to identify just how prevalent – and pin down how strong an influence it is – this shouldn’t make us reject the current research.
And thank you for saying nice things about me.
It also helps that human eyes have white parts (sclera) which allows us to communicate in a way that chimps just can’t (since their eyes are completely dark brown) – it allows an individual to infer where another human is looking and also makes it easier to relay emotions. Even dogs are able to recognize visual cues from humans.
This is the reason why the super-intelligent ape characters in the movie ‘Rise of the Planet of the Apes’ all had green irises with humanlike white scleras to give them more on-screen personality, presence and empathy. If they had dark eyes it would be harder for the human audience to connect with them.
I really liked that film; although my love of primates may have biased me somewhat.
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Compared to other animals, humans clearly have a massively enhanced ability to “respond” to things that aren’t really there. Witness: religion, morality, nationalism, every political movement, love, friendship, memberships, ownership, rules, regulations, ideas about history, money, progress, and so on. Call them what you will, it’s almost impossible to imagine life without this mental overlay of myths, narratives, group hallucinations, and so on – it would be unbelievably and maybe distressingly “flat.”
These myths obviously have a enormous adaptive value. They enable or require individuals to override basic “biological” responses, they can incorporate accumulated wisdom and science into decision-making, and they produce highly coordinated responses across groups of otherwise independent individuals separated in time and space. The obvious downside of myths is that they are frangible and require maintenance and habituation.
Consider money: We imagine that money – a class of pieces of paper printed with funny text and pictures – has some kind of intrinsic value so we operate on this basis; people will do more or less any thing to get hold of it. But a moments consideration reveals that this is clearly an illusion, it’s value is not intrinsic but relies purely on the fact that the illusion is shared. Various historical upheavals have made currencies worthless. Illusions like money and property rights evaporate during wartime. Even in normal stable life the “value” of money is being constantly reduced by inflation, but we don’t notice. (Economists regard this has healthy and desirable as it promotes investment and consumption rather than hoarding.)
It is interesting to consider the role of myths in these watcher experiments. When the chimp “steals” the food it’s just a relatively simple here-and-now calculation calculation or risks and benefits. Even if the chimp had the same basic biological response to the “watching eyes” as humans, the situation is quite different. For the chimp, the owner of the eyes doesn’t appear to be present and once the food is gone the event is over.
The human has to contend with the myth of “ownership”, a mysterious association between the food and the owner person, a hallucinated relationship that can only be broken by other rituals, like payment or gifting. Transgressing the ownership myth, would actually put you on the downside of the morality myth, which can make you a “bad” person, both socially and internally. Ongoing punishment is a potential outcome, ranging from verbal abuse and physical attack (like the chimp) but may also involve loss of status or ongoing sanctions. You might even get incarcerated for a period, and if you subscribe to certain other myths, you may believe that you will incarcerated for eternity in the fiery pits of Hell. Our culture includes a powerful myth of always being watched and all transgressions being totted up for eventual reckoning. The chimp doesn’t have to contend with any of that, he just grabs the goodies and endures a short term risk.
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