In 1845, Sir John Franklin led a British expedition in search of the fabled Northwest Passage. Equipped with two of the finest arctic vessels of the day manned by an experienced crew, confidence was high that the British would finally punch through the remaining uncharted sea and ice and connect western Europe with East Asia. As expected, the ships spent many months locked in the arctic ice. Unexpectedly, Franklin died two years into the journey, the seasonal thaw was insufficient to free the ships in the Spring of 1848 and onboard supplies of food and coal rapidly dwindled. The order to abandon ship was given and the remaining crew decamped to King William Island. The exact details of how all 105 men died are unknown but reports of fragmentation and cannibalism among the crew are well established. For Joseph Henrich, author of The Secret of Our Success – How Culture is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter, the juxtaposition of this failed expedition with an Inuit population successfully living on King William Island exposes the role of culture in the survival and, yes, evolution of the human species.

To understand Henrich’s essential point, it is important to appreciate two underlying premises. First, non-human species are pretty smart. In laboratory tests of space, quantity and causality, chimpanzees and orangutans earn similar scores as do toddler-aged humans. Second, there is a difference between individual learning, social learning and cultural learning. Given their toddler-like intellect, non-human primates are fairly adept at individual learning of simple tasks like using a rock to crack open nuts or using a stick to probe trees for tasty insects. However, at some point, human ancestors took a learning leap and started passing along more complex tasks through social learning. As these ancestors began living and cooperating in larger and larger groups, opportunities for one member of the group to hit upon a productive practice (effective rock throwing, better spear making, longer spear throwing…) and serve as a model to be copied by others become more common. Eventually, such practices create a culture and, without ever knowing their origins or why they are the most effective solutions to local challenges, generation after generation of human ancestors engaged in cultural learning. Such cultural learning allowed our ancestors to beat out the competition as a group working efficiently without the demand for extensive biological evolution.

The key to explaining why our lineage crossed the Rubicon and so many other species have not is to understand how we solved the start-up problem: bigger brains calibrated to rely on learning from other can’t pay for themselves unless there is already a lot to learn out their in the minds of others. So, assuming we are starting with a creature with good individual learning abilities (e.g., big apes), we first consider the conditions that would favor increasing the amount of know-how that one could potentially learning without increasing brain size. Terrestriality gives a boost by providing better opportunities for individual learning and more chances for social learning. Predation, by forcing primates to live in larger groups for protection, increases the size and interconnectedness of groups. Both terrestriality and predation will thereby increase the size of groups’ cultural repertoires and may begin to push a species past the threshold.

Henrich places the Rubicon moment at 1.8 million years ago. Up to that point, natural selection as described by Darwin and Wallace was the genetic driving force as our ancestors moved from Australopiths to Homo erectus. Equipped with a sufficiently large brain with differentiated hemispheres, the capacity for tool creation, social learning and problem solving took off to the point that cultural practices began to inform genetic adaptations. For example, Homo erectus gained the ability to improve biological digestion by processing food prior to eating. These processing enhancements, including cooking, allowed for more energy extraction from food which created a selective force for smaller teeth and small guts which led to anatomical changes in the jaw, shoulders, wrists and rib cages. These biological changes allowed for more complex tool use leading to more complex cultural practices which eventually yielded a deeper understanding of plants, sophisticated cooking practices and eventually to agriculture and livestock. The genetic consequences of these more recent cultural advances, from lactase persistence to blue eyes, are well established.

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The interplay between cultural learning and evolution are significant and, from our modern pestle, all too easy to discount. Those of us in the West are so far removed from understanding the central role of cultural learning that we often confuse problems with solutions as demonstrated by our fascination with all things “natural”.

For many Westerners, “it’s natural” seems to mean “it’s good.” This view is wrong and comes from shopping in supermarkets and living in landscaped environments. Plants evolved toxins to deter animals, fungi, and bacteria from eating them. The list of “natural” foods that need processing to detoxify them goes on and on. Early potatoes were toxic, and the Andean peoples ate clay to neutralize the toxin. Even beans can be toxic without processing.

On a related, intellectual level…

A device or technology often pre-existed the development of any casual understanding, but by existing, such cultural products opened a window on the world that facilitated the development of an improved casual understanding. That is, for much of human history until recently, cumulative cultural evolution drove the emergence of deeper casual understandings much more than causal understanding drove cultural evolution.

To further demonstrate the power of cultural learning, Henrich introduces us to two hypothetical prehuman groups he calls the Geniuses and the Butterflies. Being ever so clever, the Geniuses devise an important invention once in 10 lifetimes. The Butterflies are a bit dull and arrive at the same invention once every 1000 lifetimes. However, the cost of their brilliance is that the Geniuses are no all that social, each having only 1 friend they can learn from. Meanwhile, our dumb, social Butterflies each have 10 friends. The learning begins and because it is tricky business, the details of the invention only get transmitted to a friend 50% of the time among both the Geniuses and the Butterflies. After a few thousand lifetimes, we will see that only about 18% of the Geniuses have the invention, half of whom figured it out for themselves, while greater than 99% of the Butterflies know about it despite the fact that less than 1% got there on their own.

Bottom line:  if you want to have cool technology, it’s better to be social than smart

It is important to appreciate that Henrich is arguing for an expansion of the canonical view of evolutionary forces as put forth by the likes of Richard Dawkins and Steven Pinker. In a Dawkins/Pinker world, kin selection (favoring those more genetically related to you more) and reciprocal altruism (you help me I’ll help you) are all that is needed for natural selection to produce a cooperating species. Heinrich claims that such “innate proclivities” are too weak to explain cooperation in real human societies citing evidence of cooperation extending to distant genetic relatives and many non-relatives within the small, nomadic, hunting-and-gather societies of today. For Henrich, group-wide cooperation is a product of cultural evolution that promotes our biological survival.

Sir John Franklin and his ill-fated crew had all the genetic capacity to survive for months, even years, in the harsh arctic environment. What they lacked was the cultural evolution of the local Inuit people. Without knowing how to build shelter or efficiently obtain food in the arctic environment, the Europeans’ chances for survival were low. Once they resorted to cannibalism, a cultural taboo for most including the Inuit, their chances of surviving through cultural cooperation were similarly narrow. Even if the Inuit shared their know-how, they would have been hard pressed to explain to the Europeans why their kayak building or seal hunting techniques worked worked so well. For Henrich, cultural adaptations like those of 19th century Inuit are, whether we understand them entirely or not, the force that has driven our survival and genetic changes for the past 2 million years and his argument is well worth reading. Strongly recommended.