Evolution targets peripheral, not central, aspects of cognition; specialization for language processing has focussed on perceptuomotor aspects of speech rather than on an innate universal grammar

Sinking In: The Peripheral Baldwinisation of Human Cognition. Cecilia Heyes, Nick Chater, Dominic Michael Dwyer. Trends in Cognitive Sciences, September 24 2020. https://doi.org/10.1016/j.tics.2020.08.006

Rolf Degen's take: https://twitter.com/DegenRolf/status/1309477141197840385

Highlights

.  Evolution targets peripheral, not central, aspects of cognition.

.  Many peripheral mechanisms have evolved via the Baldwin effect.

.  ‘Garcia effects’ on taste-aversion learning have not withstood the test of time.

.  Fear learning is ‘prepared’ by attentional rather than by learning mechanisms.

.  Specialization for language processing has focussed on perceptuomotor aspects of speech rather than on innate principles of universal grammar.

.  There is no innate module for imitation but enhanced social motivation consequently leads to greater attention to the behaviour of other agents.

Abstract: The Baldwin effect is a hypothetical process in which a learned response to environmental change evolves a genetic basis. Modelling has shown that the Baldwin effect offers a plausible and elegant explanation for the emergence of complex behavioural traits, but there is little direct empirical evidence for its occurrence. We highlight experimental evidence of the Baldwin effect and argue that it acts preferentially on peripheral rather than on central cognitive processes. Careful scrutiny of research on taste-aversion and fear learning, language, and imitation indicates that their efficiency depends on adaptively specialised input and output processes: analogues of scanner and printer interfaces that feed information to core inference processes and structure their behavioural expression.

Keywords: adaptive specialisationBaldwin effectfear learningimitationlanguagetaste-aversion learning

Concluding Remarks

The Baldwin effect has seemed promising for a very long time. For more than a century it has been poised to revolutionise our understanding of the evolution of complex behavioural traits, but convincing empirical demonstrations have been elusive. We have argued that there is now compelling evidence of the Baldwinisation of cognition from Drosophila, and that research in cognitive science indicates that peripheral rather than central cognitive mechanisms have been the primary targets of selection.

Why might selection operate primarily at the cognitive periphery? A parallel with the evolution of other biological mechanisms is suggestive: internal physiological processes and anatomical structures are remarkably well-conserved. The organisation of the digestive, circulatory, and respiratory systems is similar across vertebrate species, and they are so deeply interconnected that modifications beyond changes of size and shape may be difficult without causing substantial collateral damage. Moreover, even such modest changes to central systems will impact on a wide variety of functions and may therefore not be under strong selection from any one function. By contrast, interfaces with the external environment (jaws, teeth, digestive enzymes, bone and muscle structure) can be adapted to local circumstances (e.g., food sources) without interfering with central systems. The central machinery of cognition is less well understood, but may be equally interlocking, with widespread functional ramification, and a consequent resistance to evolutionary change.

Alternatively, it is possible that central cognitive processes are fully evolvable, but, at least in the human case, tend to be adaptively specialised by cultural rather than by genetic selection [101]. In domains such as language, imitation, mathematics, and ethics, changes to central mechanisms can be acquired through cultural learning. Cognitive skills that are taught, and those that are learned from others through more informal social interaction, do not need to sink in. Baldwinisation would bring little if any fitness advantage for skills that are reliably inherited via a non-genetic route [17], and specialised central mechanisms may be more teachable than specialised peripheral mechanisms. Plausibly, it is easier to learn grammatical constructions than vocal control through conversation, and, in the case of imitation, easier to learn sensorimotor mappings than intrinsic motivation through non-vocal social interaction.

These possibilities warrant further investigation, but the main purpose of this article is to draw attention to empirical work and to encourage testing for Baldwin effects in cognitive science (see Outstanding Questions). Many nonspecialists assume that research on taste aversion, fear learning, language, and imitation has produced solid evidence of genetically specialised learning mechanisms. This view is outdated. Careful empirical work, starting in the 1970s, has shown that efficiency in these domains depends on genetically specialised input and output processes, and that these cognitive equivalents of scanners and printers are likely to be Baldwin effects.

Outstanding Questions

How widespread is the Baldwin effect? For example, has it shaped face processing, episodic memory, social exchange reasoning, normative thinking, mathematical cognition, and mentalising?

Baldwinisation is plausible for human fear learning, imitation, and language because there is evidence that traits which now have a genetic basis were learned earlier in the organism’s phylogenetic history. Is this a general principle? How confidently can we infer Baldwinisation, rather than aplastic evolution, from evidence that a trait was learned earlier in phylogenetic history?

Are there cases where the Baldwin effect has operated on central cognitive processes?

What sinks in when Drosophila are artificially selected for aversion learning? Would studies of experimental evolution using two cue modalities and two types of outcome confirm the evidence from rats that peripheral processes are Baldwinised?

Research using behavioural and physiological measures suggests that young infants are especially attentive to, rather than fearful of, snakes. Can this evidence of peripheral Baldwinisation be confirmed using neurological measures of attention? Are infants better able to associate snakes with positive than with negative outcomes?

Has the motivation to align our thought and behaviour with others, for example in joint action and communication, been Baldwinised?

Many theorists argue that language was originally gestural rather than vocal. If so, are there traces of Baldwinisation of gestural communication, over and above manual dexterity required, for example, in tool use?

Can we find evidence that sequence processing and motivation have been Baldwinised specifically for imitation? For example, are there types of action, or stages in the learning process, where different computations encode action and non-action sequences for imitation and recognition? Is it easier to train infants to copy body movements (‘overimitation’) than to copy object movements?

Does cultural evolution promote, or suppress, natural selection?