The importance of the tribe in our evolutionary history has meant that natural selection has favoured in us a suite of psychological dispositions for making our cultures work and for defending them against competitors. These traits include cooperation, seeking affiliations, a predilection to coordinating our activities, and tendencies to trade and exchange goods and services. Thus, we have taken cooperation and sociality beyond the good relations among family members that dominate the rest of the animal kingdom, to making cooperation work among wider groups of people.
In fact, we have evolved a set of dispositions that allow us to treat other members of our tribe or society as “honorary relatives”, thereby unlocking a range of emotions that we would normally reserve for other family members. A good example of this so-called cultural nepotism is the visceral feeling you have when one of your nation’s soldiers is lost in battle – just compare that feeling to how you react to the news of a similar loss of a soldier from another nation. We also see our cultural nepotism in the dispositions we have to hold doors for people, give up our seats on trains, or contribute to charities, and we might even risk our lives jumping into a river to save someone from drowning, or when we fight for our countries in a war.
Of course, this nepotism is not just a positive force. It is also a trait that can be exploited by propagandists and to produce Kamikaze-like or other suicidal behaviors. But the success of cooperation as a strategy has seen our species for at least the last 10,000 years on a long evolutionary trajectory towards living in larger and larger social groupings that bring together people from different tribal origins. The economies of scale that we realize even in a small grouping ‘scale up’ in larger groups, so much so that larger groups can often afford to have armies, to build defensive walls around their settlements. Large groups also benefit from the efficiencies that flow from a division of labour, and from access to a vast shared store of information, skills, technology and good luck.
And so in a surprising turn, the very psychology that allows us to form and cooperate in small tribal groups, makes it possible for us to form into the larger social groupings of the modern world. Thus, early in our history most of us lived in small bands of maybe 50 to 200 people. At some point tribes formed that were essentially coalitions or bands of bands. Collections of tribes later formed into chiefdoms in which for the first time in our history a single ruler emerged.
Eventually several chiefdoms would come together in nascent city-states such as Catal-Huyuk in present day Turkey or Jericho in the Palestinian West-Bank, both around 10,000 years old. City-states gave way to nations states, and eventually to collections of states such as the United Kingdom or the United States, and even in our modern world to collections of nations such as seen in the European Union. At each step formerly competing entities discovered that cooperation could return better outcomes than endless cycles of betrayal and revenge.
This is not to say that cooperation is easy, or that it is never subject to reversals. Just look at the outpouring of cultural diversity that sprang up with the collapse of the Soviet Union. Despite being suppressed for decades, almost overnight Turkmenistan, Uzbekistan, Kazakhstan, Chechnya, Tajikistan, Moldova, Kyrgyzstan, and Dagestan reappeared, all differentiated by culture, ethnicity, and language.