Evolution of the social discount rate

Peter D. Sozou argues in the Proceedings of the Royal Society B: Biological Sciences (Individual and social discounting in a viscous population) that caring about the long-term welfare of one's local community may make evolutionary sense because it benefits one's kin. But,

What of a social discount rate for decisions that impact on the whole population, rather than a locality or specific group? This question arises, for example, in the problem of global climate change. In the absence of competition between planets, there is no basis for behaviours that benefit the planet as a whole to be directly adaptive, and therefore no evolutionary basis for directly determining a social discount rate for global welfare. This seems to lead to a puzzle: why do people care at all about the long-term welfare of humanity as a whole? People may have evolved preferences for positive valuation of long-term general social welfare in ancestral environments in which such preferences would have mainly or always influenced actions with only local effects, and that therefore would have helped kin. But in the modern, global environment, such preferences may cause people to care about global problems such as climate change.

A more plausible explanation is that, as expected by an evolutionary analysis and as shown by people's actual behaviors, people do not really care about the future of humanity but do try to appear as if they care. Appearing to care may be adaptive because it may help to attract partners and friends.