Innateness

Its commonplace, in both scientific and popular writing to talk about innate human traits, "hard-wired" behaviors or "genes for" everything from alcoholism to intelligence. Sometimes these traits are supposed to be general features of human cognition—sometimes they are supposed to be individual features of particular people. The nature/nurture distinction continues to dominate thinking about development. But its time for innateness to go.

Of course, for a long time, people have pointed out that nature and nurture must interact for a particular trait to develop. But several recent scientific developments challenge the idea of innate traits in a deeper way. It isn't just that it's a little of both, some mix of nurture and nature, but that the distinction itself is fundamentally misconceived.

One development is the very important new work exploring what are called epigenetic accounts of development, and the new empirical evidence for those epigenetic processes. These studies show the many complex ways that gene expression, which is what ultimately leads to traits, is itself governed by the environment.

Take the maternal mice. Meaney and colleagues took two different but genetically identical strains of mice which normally develop different degrees of intelligence and cross-fostered them—the smart mice mothers raised the dumb mice pups. The result was that the dumb mice developed problem-solving abilities similar to those of the smart ones and this was even passed on to the next generation. So were the mice innately dumb or innately smart? The very question doesn't make sense.

Here's a similar human example. There is increasing evidence for an early temperament difference between "orchids" and "dandelions". Children with some genetic and physiological profiles appear to be more influenced by the environment, both for good and bad. For example, a recent study looked at the level of Respiratory Sinus Arrhythmia, basically the relation between heartrate and breathing, in at-risk poor children. They discovered that children with high RSA who had secure relationships with their parents had fewer behavior problems later than low RSA children. But the relationship was reversed for the children who had difficult relationships—they actually had more problems. So were the children innately more or less difficult or troubled?

The increasingly influential Bayesian models of human learning, models that have come to dominate recent accounts of human cognition, also challenge the idea of innateness in a different way. At least since Chomsky, there have been debates about whether we have innate knowledge. The Bayesian picture characterizes knowledge in terms of a set of potential hypotheses about the world. We initially believe that some hypotheses are less probable and others are more so. As we collect new evidence we can rationally update the probability of these hypotheses. We can discard what initially looked very likely and eventually accepting ideas that started out as longshots.

If this picture is right there is some sense in which everything we will ever think is potentially there from the start. But it is also true that everything we think is subject to revision and change with increasing evidence. From this probabilistic perspective it also isn't at all clear what it would mean to talk about whether knowledge is innate or learned. You might say instead that some hypotheses initially have a very low or very high probability of being confirmed by further evidence. But the hypotheses and evidence are inextricably intertwined.

The third development is increasing evidence for a new picture of the evolution of human cognition. The old "Swiss Army Knife" picture of capital E capital P "Evolutionary Psychology" with the evolution of myriad different constrained "modules" looks increasingly implausible. Instead, the more recent and more biologically plausible picture is that the developments involved more general developmental changes. These included an increase in the Bayesian learning abilities I just described, increased cultural transmission, wider parental investment, longer developmental trajectories, and greater capacities for counterfactual thinking. All this led to feedback loops that rapidly transformed human behavior.

The evolutionary theorist Eva Jablonka has described the evolution of human cognition as more like the evolution of a hand—a multipurpose flexible tool capable of performing unprecedented behaviors and solving unprecedented problems—than like the construction of a Swiss Army Knife.

In particular, a number of theorists have argued that the difference between the early emergence of "anatomically modern" humans and the much later emergence of "behaviorally modern" ones is due to these feedback loops rather than to some genetic change.

For example, small changes in the capacity for cultural learning and the period of protected childhood in which that learning can take place, could initially lead to small changes in behavior. But the "cultural ratchet" effect could lead to the rapid and accelerating transformation of behavior over generations, especially as there was more and more interaction within groups of early humans.

Combining cultural transmission with Bayesian learning means that each generation of children can integrate the cumulative information of early generations. As a result they can imagine alternative ways that the social and physical environment might be structured and can implement those changes. But this means that each successive generation of children will also grow up shaped by a new social and physical environment, unlike the ones that have gone before, and that in turn will lead them to make new discoveries, reshape the environment again and so on, in an accelerating process of cognitive and behavioral transformation.

All three of these scientific developments suggest that almost everything we do is not just the result of the interaction of nature and nurture, it is both simultaneously. Nurture is our nature and learning and culture are our most important and distinctive evolutionary inheritance.