The book's approach is rather unorthodox in mixing and integrating economic analysis with perspectives from different academic disciplines, such as biology, anthropology or psychology.
A few ideas that stand out:
1) 'Tunnel vision' (the capacity to play one's part in the complex enterprise of creating the prosperity of a modern society without caring much for the overall outcome) is a skill that was unknown to our hunter-gatherer ancestors. It is a social rather than a biological talent, though it channels powerful biological capacities, and it has developed during the ten thousand years that separate us from the first farmers of the Neolithic era.
2) Two kinds of dispositions have proved important to our evolution: a capacity for rational calculation of the costs and benefits of cooperation, and a tendency for what has been called strong reciprocity (the willingness to repay kindness with kindness and betrayal with revenge, even when this is not what rational calculations would recommend).
3) Over the course of human evolution on the 6 or 7 million years since our last common ancestor with chimpanzees and bonobos, children have been, on average, very slightly less intelligent than their parents. On the other hand, over the same period, each generation's parents have been, also on average, very slightly more intelligent than the children's grandparents.
4) Parent genes are combined randomly. This fact points towards equal inter-generation intelligence levels. However, genetic mutations are known to be overwhelmingly damaging. Hence, the combined effect of combination and mutation, over billions of children, is to bring average intelligence down. The other explanatory element to take into account is the subtle difference between the terms ‘children’ and ‘parents’. The second term only comprises the selection of individuals who survived and succeeded in reproduction.
5) Thus, the above-mentioned intelligence-related statements can be explained thanks to the two most fundamental ideas in statistics. Firstly, the law of large numbers states that the average behavior of a large group of similar individuals will be more predictable than the behavior of a small group or any one individual. Secondly, the statistical idea of conditional probability relates to the need to account for what other information we have in making any given prediction.
6) The progressive evolution of a human capacity to exchange goods and favors between unrelated individuals has brought about three significant and defining social benefits: risk-sharing, specialization and the accumulation of knowledge.
7) Contrary to what one might conclude from the tone of much recent press, globalization and its challenges are not new but a continuation of social developments of at least the last ten thousand years. To manage the hazards imposed on us by the actions of strangers has required us to deploy a different skill granted to us by evolution for quite different purposes: the capacity for abstract symbolic thought.
8) Modern political institutions temper appeals to deep emotions, to family and to clan loyalty, with just enough abstract reasoning to help Homo Sapiens Sapiens, the shy, murderous ape, emerge from the savanna woodlands in order to live and work in a world largely populated by strangers. This experiment is still young, and needs all the help it can get.
In summary, The Company of Strangers is a though out book with deep and very relevant insights. Without a doubt, a recommendable read. Particularly in these fragile times that seem edging gradually closer to total social unrest.