A primate brain in a human world: Evolutionary biology and social change

March 6, 2019

     By Duncan Green     

Guest post from Sebastian Bock. Full disclosure: I’ve been mentoring Sebastian during his fellowship at the LSE’s Inequalities Institute. This was my favourite of his posts on social change. You can find the rest of the series on the Atlantic Fellows for Social and Economic Equity blog or on Medium.com.

Shame. It might make most of us feel horrible, but it has also become a well-known part of the toolbox of modern social-change campaigning. And often with great success. In the realm of campaigns to change corporate behaviour, “shaming” those companies has become an important tactic.

While most people – based on their personal experience of shame – have a basic understanding of why “shaming” works to affect behaviour, more profound explanations for the mechanisms at work can be found by looking at our very distant past. Not only can we find explanations for why this approach works, but we can also gain insights into its limitations – and what that means for some of the defining challenges of our times, such as inequality and climate change.

To get there, we will need to take a trip down memory lane: a long, long trip, back to the days of our  ancestors. We will start, however, with what has become one of the most cited scientific articles ever written. There are probably less than a handful of people who have graduated in the field of economics and have not had to read ecologist and philosopher Garrett Hardin’s seminal paper, “The tragedy of the commons”. And for good reason. Hardin’s argument is elegant, simple and convincing, albeit not necessarily universally true.

Hardin is trying to answer the question of what will happen to a resource that is communally owned, like public lands or our atmosphere. He focuses on the English commons, land that formally belonged to the king but was available to everyone. His argument was straightforward: in such a situation, “each herdsman will try to keep as many cattle as possible”, because while overgrazing will ultimately destroy the land for everyone, that fact should not change a rational herdsman’s behaviour. The reason, according to Hardin, is simple: while all users of the commons will share the “costs” of overgrazing, the “profits” from each additional animal will be the herdsman’s.

If we assume that a herdsman’s decisions are mainly motivated by their self-interest (in this case maximising profits by grazing as many of their cattle as possible), Hardin’s argument is very compelling. And if we look at some of humanity’s biggest commons – like the atmosphere or the fish in our oceans – this seems to be exactly what is happening. While everyone will share the costs – climate change – of my holiday flight to Hawaii, the benefits are all mine to enjoy. Self-interest trumps the common good and therefore ultimately risks destroying the most important commons of all.

So it seems like Hardin was right. Except he wasn’t. At least not always. While his model seems to work whenever the commons is really big, more recent research has found that in smaller commons – including his own example of the English commons – people behave very differently from what he predicted. The question is why.

So far, we have mostly looked to social sciences for answers to that question. But perhaps part of the answer is in our biology.

In 1992, Robin Dunbar, a specialist in primate behaviour at the University of Oxford, started to notice something interesting. Primates seemed to live in groups of a certain size. That size was different for different primate species, but similar within the same species. Smaller groups tended to grow to a certain size but once they exceeded it, group dynamics changed or broke down and the groups usually split up. While the phenomenon was easy enough to observe, nobody seemed to be able to explain what determined the size of the groups. Until Dunbar started looking at the size of different primates’ brains. What he found was very interesting: brain size was clearly correlated with group size of a specific species of primates. That correlation became known as “Dunbar’s number”. For humans, that number is around 150.

Why 150? While we don’t know for sure, scientists think that the reason is that for most of human history we lived in much smaller groups. In other words, our evolution prepared us for a life that is very different from that of most of us today. Only after we switched from a  hunter-gatherer lifestyle to agriculture-based societies did we start to live in much larger groups than our ancestors. While our lifestyles have changed dramatically since the advent of the first agricultural revolution about 12,000 years ago, our biology hardly changed at all.

Although 150 seems like a relatively small number, Dunbar has illustrated what this number actually means in terms of complexity of group relationships that we need to keep track of. If we look at an average modern family of five people, we have to keep track of 10 separate relationships: our relationships with the other four family members as well as the six other two-way relationships between the others. However, if you add your extended family – say a group of 20 people – you now have to keep track of 190 two-way relationships: 19 involving yourself as well as the 171 relationships between the other family members. I will spare you the math for a group of 150 people, but this example illustrates why understanding the social dynamics in a group of that size is no easy feat.

If Dunbar is right, and subsequent research suggests he is, we are biologically equipped to self-govern groups of up to 150 people. Interestingly, as author Malcolm Gladwell reports, when looking at “21 different hunter-gatherer societies for which we have solid historical evidence, from the Walbiri of Australia to the Tauade of New Guinea to the Ammassalik of Greenland to the Ona of Tierra del Fuego [Dunbar] found that the average number of people in their villages was 148.4”. In groups up to that size, social cohesion seems to be enough to make sure that we can live together without infighting within the group or destroying our livelihoods.

The main “enforcement mechanism” of that social cohesion seems to be shame. In groups up to that size, people’s personal relationships with their peers are strong enough that the emotion of shame serves as a powerful deterrent to prevent members from acting against the group’s best interest.

Most of us, of course, live in groups that far exceed that number. And most of the time we manage to do that without all hell breaking loose. We are able to do that because we have created formal structures to enable us to manage relationships with much bigger groups of people than we (pre-)historically had. Those structures serve us well in many circumstances. But they fail us in others, namely in those cases where we are facing problems that exceed our formal governance structures. Problems such as climate change or global inequality. Problems in which the actions of one group have consequences for another, but in which shaming doesn’t work because of the size of the group, and in which formal structures don’t work because they don’t exist.

This has been an intractable problem for a long time, with no obvious solution in sight. The global structures set up to deal with such problems have had limited success. On the issue of climate, they are delivering too little, too late. On the problem of global inequality, most indicators are pointing in the wrong direction. Despite those issues, most problems of this scale still require a global solution. At the same time, it is worth exploring whether there are other ways that can help solve today’s problems.

Prehistorical tragedy of the commons problems were often solved (or avoided) by the first shame campaigns in history. Maybe today we need to reinvent the tradition of shame campaigns, adjusted to work for much bigger commons. One way of doing so would be to take a closer look at peer groups. New research by Robin Dunbar has found that even in the age of Facebook, “the size and range of online egocentric social networks, indexed as the number of Facebook friends, is similar to that of offline face-to-face networks”. Of course we know many more people, but the size of group of people who are close enough to really have an influence on us seems to not have changed.

This suggests that the same mechanisms are still at work, and it might be worth thinking about ways of using them better. Rather than just looking at how power is distributed in the formal power structures we are used to, be they in government or in business, we ought to spend more time looking at the informal structures surrounding those in power. Identifying the informal peer groups, the groups where shame works as a governance mechanism, might allow us to translate the big commons problems we currently struggle to solve into small commons problems that we are biologically better equipped to deal with.

Sebastian Bock is an Atlantic Fellow for Social and Economic Equity in the International Inequalities Institute at the London School of Economics (LSE) and a Senior Strategist at Greenpeace International. You can follow him on Twitter @sebastianbock