Thomas Grund, Christian Waloszek & Dirk Helbing
Biological competition is widely believed to result in the evolution of selfish preferences. The related concept of the ‘homo economicus’ is at the core of mainstream economics. However, there is also experimental and empirical evidence for other-regarding preferences. Here we present a theory that explains both, self-regarding and other-regarding preferences. Assuming conditions promoting non-cooperative behaviour, we demonstrate that intergenerational migration determines whether evolutionary competition results in a ‘homo economicus’ (showing self-regarding preferences) or a ‘homo socialis’ (having other-regarding preferences). Our model assumes spatially interacting agents playing prisoner's dilemmas, who inherit a trait determining ‘friendliness’, but mutations tend to undermine it. Reproduction is ruled by fitness-based selection without a cultural modification of reproduction rates. Our model calls for a complementary economic theory for ‘networked minds’ (the ‘homo socialis’) and lays the foundations for an evolutionarily grounded theory of other-regarding agents, explaining individually different utility functions as well as conditional cooperation.
... In conclusion, we offer an over-arching theoretical perspective that could help to overcome the historical controversy in the behavioural sciences between largely incompatible views about human nature. Both, self-regarding and other-regarding types of humans may result from the same evolutionary process. Whereas high levels of intergenerational migration promote the evolution of a ‘homo economicus’, low levels of intergenerational migration promote a ‘homo socialis’, even under ‘Darwinian’ conditions of a survival of the fittest and random mutations. The significance of local reproduction for the evolution of other-regarding preferences is striking and may explain why such preferences are more common in some parts of the world than in others.
Our modelling approach distinguishes between the evolution of individual preferences and behaviours. This makes cooperation conditional on the level of cooperation in the respective neigh-bourhood. Hence, when a few ‘idealists’ are born, who cooperate unconditionally, this can trigger off cooperation cascades, which can largely accelerate the spreading of cooperation33. Our model can also serve as a basis to develop an economic theory of other-regarding agents. The advantage is that it does not need to assume certain properties of boundedly rational agents—these properties rather result from an evolutionary process. In fact, our model naturally explains the evolution of individually different utility functions, as they are experimentally observed (see Figs. 3 + 4), and also the evolution of conditional cooperators9, 34.