In 1859, Darwin explained that species had their origin not in fate but blind chance: traits were passed on depending on how adapted they were to helping individuals survive, and reproduce, in a harsh world characterised by competition over scarce natural resources.

Societies, like species, survive or perish depending on their management of resources. And like species, societies evolve depending on which traits are best for reproducing the code for those observable traits. In natural evolution that code is genes. In social evolution, I argue, that code is technology, which allows us to transform natural resources to meet our human needs.
Just as genes require organisms to carry and propagate then, so does technology require a social carrier to promote its growth and development, and enable its mutation. What are these social carriers?
History suggests that technology rises fastest under two conditions:
1. first, when states are fighting each other in wars, developing technology to defend themselves against the threat of military destruction;
2. second, when classes are competing in trade for resources, developing technology to defend themselves against the threat of economic destruction.
The industrial revolution, for instance, was preceded by wars among European states, including England, as well as by the rise of two new classes to supersede the old dialectic of lords and serfs — namely, those who owned factories and new economic technologies, and those who worked in those factories and with those technologies to produce profits for their new masters.
Modern societies, at least, seem to have their origin in a process of social evolution, where war selects for those states that can best develop technology for military purposes, and trade selects for those classes that can best develop technology for economic purposes. Classes and states, like organisms, strive to reproduce technologies, like genes, under the selective pressures of trade and war. Whole societies, like species, have their origins in an evolutionary process, just not quite the same one as Darwin envisaged, all those years ago.