Review of The Secret of Our Success:  How Culture is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter.  By Joseph Henrich.  Princeton University Press.  445 pp.  $29.95.

Human beings are smart.  But, according to Joseph Henrich, the impact – and import – of the innate intelligence of individuals may be over-rated.  In a variety of cognitive tests related to space, quantities, and causality, for example, two and a half year olds did not outperform chimpanzees.  Quite often, moreover, European explorers who got lost did not survive.  The takeaway, Henrich suggests, is that our species’ uniqueness lies “less in the power of individual minds than in the collective brains of our communities.”

In The Secret of Our Success, Henrich, who holds professorial appointments at Harvard and the University of British Columbia, draws on the latest findings in anthropology, linguistics, behavioral economics and psychology, and evolutionary biology, to present a provocative alternative to the standard narrative about evolution.  Human beings, Henrich argues, are not simply bigger-brained, less hairy chimpanzees.  Homo erectus is a new kind of animal, dependent on “cumulative culture for survival, on living in cooperative groups, on allo-parenting and a division of labor and information, and on communicative repertoires.”  A work in progress, in a new, multi-disciplinary field, Henrich’s book is immensely ambitious, informative and important.

Henrich dares to speculate.  He explains why our ancestors crossed the Rubicon and began to rely on cultural know-how in the last few million years and not before.  He provides a plausible – and provocative – analysis of the inability of other species to solve “the start-up problem” and “exhibit similar culture-gene co-evolutionary trajectories.”

And Henrich speculates that three cases of cumulative culture driving genetic evolution (the appearance of blue and green eyes among cereal dependent populations in northern latitudes; the correlation between the flourishing of rice agriculture and the spread of a new version of the gene ADH1B that metabolizes alcohol more efficiently in the liver; and the concentration of genes conducive to lactase persistence among European people) “represent the tip of the iceberg.”  Culturally transmitted knowledge (about, for example, making and maintaining fires to warm bodies and cook food; tracking prey, throwing projectiles and designing bows and arrows to kill them), he claims, was the primary generator of producing evolution, generating selection pressure “on an immense spectrum of traits, ranging from dry earwax and malaria resistance to skeletal development and the digestion of plant toxins.”

As they supplied “prebuilt mental models” for how things work, models that neither individuals nor groups were likely to figure out if left to their own devises, Henrich adds, culturally constructed environments also altered brain architecture, hormones, and bodies non-genetically.  The two processes, of course, were related and inter-acted with one another.  He cites one study, for example, that demonstrated that people drinking wine they thought to be expensive exhibited more activation in the medial orbitofrontal cortex, the region associated with pleasure for odors, taste and music.  And that the preferences (and neurological responses) of others was strongly influenced by observation of the cues provided by “experts.”

Like virtually all books that aspire to shift paradigms, The Secret of Our Success does not satisfactorily address all of the myriad issues it raises.  Henrich does not make a compelling case for his suspicion that natural selection has psychologically linked the presence of prestigious individuals with an increase in “pro-social” behavior, “especially generosity,” of other people.  Nor is it entirely clear whether one can keep prestige and dominance separate, even if the underlying cognitive and emotional patterns associated with them, as well as the implications for cooperation, are distinct.

More research is needed as well to tease out the implications of Henrich’s claim that in a rapidly changing society, like the one in which we live, accumulated knowledge becomes less valuable.  And to define with greater precision his use of the term “success.”  After all, it seems to me, cultural inheritance has had a downside.  It does, indeed, often promote group harmony, foster internal cohesion, and favor reproduction and longer, healthier lives.  But it also promotes inter-group competition that can be deadly, through culturally transmitted beliefs such as nationalism and racism.

In our complex twenty-first century world, Henrich concludes, technological innovation will depend increasingly on the size and connectedness of people at or near the edge of the knowledge frontier, “who know enough to potentially take the next baby step or to recognize a lucky mistake.”  And on the capacity and willingness of leaders to enact policies that make it relatively easy to acquire information and experiment with it without incurring significant costs.

Since the conditions that fostered population grown, the establishment of larger societies, trust, fairness and intra-group cooperation, backstopped by laws, courts, and police – a stable global climate and an enhanced capacity to produce food – may change, we have ample incentives to join Henrich’s quest to better understand ourselves as “a new kind of animal,’ by embracing the new kind of evolutionary science which he practices so well.

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