Blueprint

The social suite, as Christakis lays it out, is a package of eight related things that show up wherever humans form durable groups. The capacity to have and recognise individual identity. Love for partners and offspring. Friendship. Social networks. Cooperation. A preference for one's own group, what he calls in-group bias. A soft, informal hierarchy rather than rigid domination. And social learning and teaching. Take any functioning human community, from a Silicon Valley office to a Hadza foraging band, and you find the same eight features doing the same load-bearing work.

He grounds the claim in comparison rather than assertion. When anthropologists survey small-scale societies with no contact with the modern world, the same features recur. When Christakis studied a set of isolated communities in Honduras, mapping who was friends with whom, the structure of those friendship networks looked statistically like the networks of American college students and Rwandan villagers alike. People everywhere have roughly the same number of friends, form roughly the same kinds of clusters, and are kind to friends of friends in roughly the same way.

The heart of the book is the claim that natural selection, the same process usually invoked to explain our violence, built our goodness too. This is not sentimental. Christakis walks through the mechanics of how a blind, amoral process could favour love, loyalty and friendship, and the answer is that these traits pay.

Take love. Pair-bonding — the tendency to form a lasting attachment to a mate — is rare among mammals but strong in humans, and Christakis ties it to the brutal arithmetic of raising a helpless, slow-growing child. A human infant is expensive and defenceless for years. Parents who bonded and cooperated raised more surviving children than those who did not, and the neural machinery of attachment, the oxytocin and the reward circuits, got passed along. What feels like the least biological thing about us — devotion — is among the most.

Step back from the shipwrecks and the elephants and Christakis's larger quarrel comes into view. For most of the twentieth century, the loudest scientific stories about human nature were dark, and the loudest stories about human decency credited culture — as if institutions, religion and law had to civilise a creature that was, underneath, purely selfish. Blueprint refuses that division of labour. Culture and biology, in his telling, are not opponents. They are partners, and the partnership runs one particular way: our genes shape the kinds of societies we are able and inclined to build.

This is why he keeps returning to convergence. If good societies were purely cultural inventions, we would expect them to vary without limit. Instead, across wrecks, communes, kibbutzim and utopian experiments, the same social suite keeps reasserting itself, and the arrangements that fight it — that abolish the family, or crush individuality, or dissolve friendship into the collective — tend to fail or quietly restore what they banned. He reads the failed communes of the nineteenth century this way: the ones that survived longest were the ones that made peace with human nature rather than trying to reengineer it.

Christakis ends more or less where he began, on the strangers washed ashore who kept rebuilding the same room. The Grafton's five men did not have a better island than the Invercauld's crew. They had a better grip on the parts of human nature that let a group survive — and those parts, Blueprint argues, were not invented on the beach. They were carried there, in the same bodies that also carried the capacity for cruelty and abandonment.