This is the first part of a mini-sequence of posts on zero-sum bias and the role that it plays in our world today.

One of the most pernicious of all human biases is zero-sum bias. A situation involving a collection of entities is zero-sum if one entity's gain is another's loss, whereas a situation is positive-sum if the entities involved can each achieve the best possible outcome by cooperating with one another. Zero-sum bias is the tendency to systematically assume that positive-sum situations are zero-sum situations. This bias is arguably the major obstacle to a Pareto-efficient society. As such, it's very important that we work to overcome this bias (both in ourselves and in broader society).

Here I'll place this bias in context and speculate on its origin.

Where this bias comes from

It's always a little risky to engage in speculation about human evolution. We know so little about our ancestral environment that our mental images of it might be totally wrong. Nevertheless, the predictions of evolutionary speculation sometimes agree with empirical results, so it's not to be dismissed entirely. Also, the human mind has an easier time comprehending and remembering information when the information is embedded in a narrative, so that speculative stories can play a useful cognitive role even when wrong.

Anatomically modern humans appear to have emerged 200,000 years ago. In the context of human history, economic growth is a relatively recent discovery, only beginning in earnest several thousand years ago. The idea that it was possible to create wealth was probably foreign to our ancestors. In The Bottom Billion, former director of Development Research at the World bank speculates on the motivation of rebels in the poorest and slowest growing countries in the world who start civil wars (despite the fact that there's a high chance of being killed as a rebel and the fact that civil wars are usually damaging to the countries involved)

[In the portion of the developing world outside of the poorest and slowest growing countries...] growth rates may not sound sensational, but they are without precedent in history. They imply that children in these countries will grow up to have lives dramatically different from those of their parents. Even when people are still poor, these societies can be suffused with hope: time is on their side...If low income and slow growth make a country prone to civil war, it is reasonable to want to know why. There could be many explanations. My guess is that it is at least in part because low income means poverty and low growth mans hopelessness. Young men, who are the recruits for rebel armies, come pretty cheap in an environment of hopeless poverty ...if the reality of daily existence is otherwise awful, the chances of success do not have to be very high to be alluring. Even a small chance of the good life as a successful rebel becomes worth taking, despite the high risk of death, because the prospect of death is not so much worse than the prospect of life in poverty.

Neither the developed world nor the countries that Collier has in mind are genuinely good proxies to our ancestral environment, but like the people in the countries that Collier has in mind, our ancestors lived in contexts in which growth of resources was not happening. In such a context, the way that people acquire more resources for themselves is by taking other people's resources away. The ancient humans who survived and reproduced most successfully were those who had an intuitive sense that one entity's gain of resources can only come at the price of another entity's loss of resources. Iterate this story over thousands of generations of humans and you get modern humans with genetic disposition toward zero-sum thinking. This is where we come from.

For nearly all modern humans, the utility of zero-sum bias has lapsed. We now have very abundant evidence that the pie can grow bigger and that win-win opportunities abound. Both as individuals and as representatives of groups, modern humans have a tendency to fight over existing resources when they could be doing just as well or better by creating new resources that benefit others. Modern humans have an unprecedented opportunity to create a world of lasting prosperity. We should do our best to make the most of this opportunity by overcoming zero-sum bias.