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Biology 202
2004 First Web Paper
On Serendip

Brain Modularity: Links between Evolution, Intelligence and Culture

Prachi Dave

Questions that arise during an examination of brain structure seem always to proliferate from a point of origin, that is, from the first question asked. One of the simplest question may ask, is the brain modular? And the simplest answer would be almost certainly positive. However, it is the nature and origin of such modularity that we should perhaps be concerned although the characterisation of each module is presently beyond our grasp. Brain modularity has more recently, with the marriage of psychological and evolutionary concepts, has been depicted as structure arising from evolutionary forces such that the brain constitutes a compilation of adaptations, evolved as solutions to the various adaptive problems in the environments faced by our ancestors. The amalgamation of evolutionary principles and the ideas regarding brain structure are primarily the work of Leda Cosmides and John Tooby who indicate that human reasoning is not generalised but a specialised ability and that the reasoning mechanisms (reflected in modules) are devoted to the management of social problems 1)Evolutionary Psychology an informative source for theory in evolutionary psychology. However, such an approach begs certain questions. For example, such an interaction with the social world and its problems requires mechanisms that can remember and track changes in the environment. As Henry Plotkin asserts, this mechanism is intelligence 2)The evolution of culture clearly presented ideas of a respected evolutionary psychologist. The relationship between intelligence and the modular structure of the brain on the one hand and their relationship to human culture as we see it today, in it's vast and wonderful complexity on the other, are linkages that evolutionary psychologists are currently grappling with and which will be the subject of the following paragraphs.

The field of "Evolutionary Psychology" has begun to be associated primarily with certain fixed principles and the work of Tooby, Cosmides and Pinker, among others 1)Evolutionary Psychology an informative source for theory in evolutionary psychology. Given that evolutionary psychology may strive to discover and explain psychological adaptations and their functions, such psychological adaptations in the brain must be characterised. As they developed in response to various problems in the environment, dilemmas so different from one another that they could not be solved by some abstract, generalised mechanism, they were posited to be represented in the brain as a collection of "modules" which are specialised problem-solving domains. The brain is conceptualised as a container for enormous numbers of these modules, to the extent that some extreme proponents of the theory defend the concept of "massive modularity" which maintains that the brain is riddled through and through by such modules others 3)In Defense of Massive Modularity an extreme position within the school of evolved modularity.

The modules proposed by Tooby and Cosmides are purported to have evolved in order to contend with a variety of adaptive problems encountered by our Pleistocene ancestors (since evolution as a cumulative process requires vast swathes of time, human psychological adaptations are not in accordance to modern life) such as alliance formation, kin relations, sexual attraction and so on. As these module functions are listed, an obvious problem arises, that is the difficulty of obtaining evidence for their existence. In this case, then, the desire to discover the universal structure that links together all members of our species, is severely obstructed.

Given the obvious existence of cultural and attitudinal variance, evolutionary psychologists hold no expectation of finding common human behaviours and beliefs through the discovery of modular commonality, but instead hope to uncover similarities in "cognitive Darwinian Algorithms" 1)Evolutionary Psychology an informative source for theory in evolutionary psychology which are then expressed through different behaviours among humans and are context dependent. The assumption that a wide ranging sample of behaviours may be explained through the indiscriminate application of such modules and evolutionary principles to modern life often leads individuals astray and the endeavour is known as adaptationism. Exaptations, however, are behavioural expressions of functionally empty traits or traits that evolved for different uses, while spandrels are traits which developed as byproducts of others and had no original function and yet became applied toward a different adaptive function. One claim regarding modern human behaviour originates from Gould 1)Evolutionary Psychology an informative source for theory in evolutionary psychology who argues that most "mental properties" are not adaptations but spandrels. This concept is given credence by the difficulty of explaining reading, writing and the consciousness of one's mortality as shaped by natural selection. These claims are not refuted by evolutionary psychologists and they hold that the complex design clearly evinced by the brain is typical of adapted structure. The spandrels, however, are products of evolved mechanisms and they may be what we see today in terms of the remarkable complexity of human culture.

Human culture, however, concerns another capacity whose evolution engenders yet more questions of increasing complexity. The capacity referred to here is that of intelligence and is described by Plotkin (4)as a "special kind of adaptation that generates adaptive behaviour by altering brain states." This assertion is made in the context of intelligence as a mechanism through which individuals track the changes in their environment as they occur and generate behaviours which, in turn, result in learning. Learning, which is known to result in changes in the brain, then results in the storage of information within the organism such that the experience may be applied to future dilemmas. Acquired knowledge, however, is not passed from generation to generation biologically while the evolved structure of the brain is perhaps carried through generations. Such a structure, as posited by Plotkin (4)constrains the kind of learning organisms engage in through the creation of specialised modules. However, the contribution of human intelligence to a phenomenon of human culture, which Plotkin likens (in importance) to the evolution of self-replicating molecules, is great.

Human intelligence allows for extensive learning in various fields. Culture, however, depends on the sharing and communication of that which is learnt by means of "intelligent" mechanisms. The knowledge that is shared is not isolated and fixed but forever modified and metamorphosing into different knowledge and practises and this is the consequence perhaps of communication through the complexity of human language and mediation of intelligence. Furthermore, the existence of intelligence perhaps allowed for the development of a theory of mind among humans, the ability to attribute intentions to others' mental states, which then allowed for the construction of social entities. Therefore, it seems possible that the intelligence allowed for the development of the cultural intricacies that are observed especially in human societies.

In essence, evolutionary psychology is a burgeoning field of study whose proponents believe that almost any experience or instance of human behaviour arises from evolved structure in the form of modules in the brain. This conception continues and is at risk of falling into adaptationalist modes of thought. Regardless, most evolutionary psychologists believe that a great deal of human behaviour is not a direct product of evolved structure and yet this places them in another conundrum, that is, delineation of the function of each module. Yet, the theory that the brain is compartmentalised in such a way, at least to some extent, allows for theorising about the construction and propagation (with modification and addition) of human culture, whose study is fascinating and of interest to most who ponder the origins of such complexity.


1); David J. Buller, Evolutionary Psychology, Northern Illinois University.

2); Henry Plotkin, The Evolution of Culture

3); Dan Sperber, In defense of massive modularity

4) Plotkin, Henry. The Imagined World Made Real: Towards a Natural Science of Culture. New Jersey: Rutgers University Press, 2003.

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