By Alex Danvers

Without evolution, your thinking is impoverished. In introducing speakers Leda Cosmides and Joseph Henrich at the SPSP Annual Convention symposium “Big Questions in Evolutionary Science and What They Mean for Social-Personality Psychology,” moral psychologist Jonathan Haidt argued that not reading their work is “a huge missed opportunity.”

Many psychologists see some consonance in their findings with evolutionary theory, but say, as Haidt puts it: “I don’t have to get into evolution, so I won’t.” But evolutionary approaches to human behavior allow researchers to ask “why?” questions that just aren’t part of the standard approach of many psychologists.

They also lead to deep insights. Haidt credits Cosmides with inspiring him to do away with blank slate, content-free accounts of cognitive processes. Humans don’t have generalized processing mechanisms suited for whatever gets thrown our way—we have mechanisms suited for particular types of inputs, with particular types of desired goal states.

Henrich, on the other hand, inspired Haidt to think more seriously about how culture is transmitted, and what our particular learning biases might be. Humans don’t just inherit genes, they inherit culture, and the richness of human culture has in turn shaped our genetic endowment such that we can best absorb this vital information.

In describing his approach, Henrich emphasized cases from what he described as the “Lost European Explorer” files. In these stories, he describes how European travelers to remote regions—for example, an expedition across the interior of Australia—struggled to survive in places where native peoples were thriving.

In the Australian expedition, explorers tried to make the same type of “nardoo” cakes that locals ate. What they didn’t understand were the particular preparation steps that looks took in order to render the local ingredients non-toxic, steps that had been honed and passed on via accumulating cultural knowledge. Without knowing these proper food preparation steps, the lost explorers couldn’t process the cakes and slowly starved—while the natives continued to survive. Same species, different cultures: vastly different outcomes.

Stories like this are emblematic of how much culture matters for our species survival, and Henrich goes on to list off numerous examples of genetic adaptations that take advantage of the niche humans have constructed for ourselves in developing cumulative culture—like having shorter colons in response to using fire to cook, or a predisposition to learn institutional rules and norms.

In explaining her perspective, Cosmides stressed the importance of the underlying human cognitive architecture—a term that describes mental systems honed through the repeated experience with common, fitness-relevant situations.

Cosmides, too, talks about the importance of culture—but for her, culture is a circumstance that elicits specific mental adaptations. For example, she discusses research by Hillard Kaplan and colleagues on sharing norms based on foraging. People can be unsuccessful in foraging for certain types of resources—like meat—even if they are skilled, because success is deeply influenced by luck. Other resources—like honey—can be gathered more easily if a person is skilled or exerts themselves. Thus many hunter-gatherers differentiate who they are willing to help: those who were unsuccessful because of unlucky meat foraging, versus those who are unsuccessful because of low skill or low effort honey foraging.

Differing norms in sharing, Cosmides argues, might therefore be thought of as a product of different characteristics of resources kicking into gear one of two different mechanisms that already exist in our minds. As evidence, she describes experimental results showing that even non-foraging Southern Californians pick up on the luck/skill distinction in resource foraging incredibly rapidly—and alter their sharing behavior accordingly.

For Cosmides, the speed with which this effect and others come online is indicative that they are extant parts of a common underlying cognitive architecture, not new ways of parsing the world learned via a cultural inheritance. Culture in this model is more often “evoked”—ecological differences causing variability—than created.

This differing emphasis on innate mechanisms as compared to cultural evolution and gene-culture co-evolution led some audience members to expect “blood,” as one questioner put it. But at the broad level, Henrich and Cosmides agreed.

As Cosmides put it, “we are more likely to disagree on the origin of a specific behavior”—but not on the importance of the evolutionary approach.

As Theodosius Dobzhansky famously said, “nothing in biology makes sense except in the light of evolution.” Social and personality psychologists, take heed: biology means people, too.

Alex Danvers is a PhD student in social psychology studying emotions in social interactions. He uses dynamical systems and evolutionary perspectives, and is interested in new methods for exploring psychological phenomena.