Evolutionary theory of the self

When trying to understand the self in terms of the brain, neuroscientists have found contradictory results and paradoxes. Nevertheless, Gonzalo Munevar has argued that neuroscience in an evolutionary context can give a proper explanation of the self. His Evolutionary Theory of the Self depends on, “the ability by the brain to coordinate new sensory information in light of the organism’s internal states and in the context of its personal history and genetic inheritance." His theory is an alternative conception for the explanation of the self, which takes into account the evolutionary biology of the brain.

Organisms that are highly complex execute the function of telling self from other with the brain and the immune system. To fulfill the function of recognizing self from other, the brain uses past experiences and genetic inheritance (e.g. survival, reproduction). The self is defined by these functions that distinguish an organisms from other organisms, which allow them to act as one whole entity in social and physical environments. Simply put, the theory revolves around the idea that the brain constitutes the self, which represents itself in a variety of internal states.

The brain/self evolves for action to be able to interact with social and physical environments. It is suggested that the brain performs a complex list of tasks to complete these interactions to distinguish self from other. This defines the brain to be characteristically distributive to complete complex tasks, and thus suggests that the self is also distributive. Therefore, the Evolutionary Theory of the Self detours from the traditional conceptions that include the self being a centralized, unitary mechanism that is both conscious (sense of self) and compiled of a collection of episodic memories. Alternatively, it suggests that the conception of self is mostly unconscious, and the brain evolves from past experiences and genetic inheritance to create the evolutionary self.

In Munevar’s study, “fMRI Study of Self vs. Others’ Attributions of Traits Consistent with Evolutionary Understanding of the Self,” he aimed to demonstrate the experimental feasibility of this conception of the self as a distributive system, and discovered results complimenting the Evolutionary Theory of the Self while resolving the contradictions and paradoxes of traditional conceptions of self.

Neuroscience problems and paradoxes of the self

One of the problems is that the results of brain-imaging studies of self-knowledge vary depending on the behavioral tasks chosen. Some studies use positron emission tomography (PET) to do self-attribution of personality traits, while others use functional magnetic resonance imaging (fMRI). Other studies prefer to do tasks involving self-recognition (recognizing a photograph or yourself and others). Studies that use self-attribution studies, “find neural activation of the medial prefrontal cortex (MPFC) as evidence for the self”, while studies consisting of self-recognition tasks find, “correlated activation of the right prefrontal lobe and regions of the medial and left hemisphere as evidence self-awareness and self-knowledge."

This variety of results of the studies have provided evidence for Gillihan and Farah to conclude that there is not a unitary and common neural system concerning the self, which leads into the next two problems of the traditional conception of self. These problems are that the traditional conceptions of the self argue that the self is a unified mechanism that exists in a centralized area in the brain, and that the self is something we can consciously sense. The problems with these accounts are that there is scientific research contradicting the claims of traditional conceptions. Llinas suggests that the self is a form of perception and thus that the self is an invention of the brain just as secondary sensory qualities are. He argues that there is no one brain area that could account for the self, and he concludes that the self doesn’t exist. Although Llinas is confusing the conscious and unconscious self, because when he suggests the self as a form of perception he should be referring to the conscious self being a form of perception. Munevar suggests that Llinas is incorrect in assuming the self does not exist, because just as an elephant and the perception of an elephant are different things, so are the self and our perception of the self.

Traditional conceptions also assume that the self is a collection of episodic memories, since they are memories of the actions that sculpt our personalities, and therefore closely link personality and the self. According to Klein, in a study of patients who had lost their hippocampi (the part of the brain responsible for memories), patients were able to recollect their knowledge of personality even in the absence of episodic memories. This points to show that the trait summaries of their personality must have come around subconsciously, inferring that the self can exist even in the absence of episodic memories. Thus, the self cannot be a collection of episodic memories.

Solutions to the problems

The Evolutionary Theory points out that distributive systems are characteristic of the brain. Organisms need to identify itself from others in many complex ways, thus many areas of the brain are used when distinguishes self from other. We need to understand that the brain is full of distributed mechanisms, thus creating an expectation that the self will be too. With this understanding, the Evolutionary Theory of the Self avoids all the difficulties about the unified and central mechanisms that traditional conceptions hold. In addition, the brain-based model of the evolutionary theory recognizes that the majority of the mental tasks highly complex organisms do are unconscious. Simply put, we may be aware of a decision we have made, but not the calculations that went into the decision as they are not capable to be understood by the conscious self. By attempting to take an evolutionary approach to understanding the self, the confrontation of self with the sense of self is avoided, in addition to, “all the problems that arise from an undue emphasis on consciousness.”

As suggested by Munevar, research on the evolutionary theory of self needs to firstly examine the existence of distributed activation in the brain when doing a self-attribution task. Secondly, they need to examine distinctions in brain activity when identifying self and close others in a manner of objective vs subjective to see if there are activation variances between the two. Thirdly, research needs to use non-personality traits as well as personality traits to take into account the importance of non-personality traits to the evolutionary needs of an organism. Fourthly, the research should aim to prove that humans, “should identify with those close to us, although not as strongly as with ourselves." These four aims were the four that structured the hypotheses in his study, and provide blueprint for further research to test.

Evidence to support the theory

In Munevar’s study, they compared self vs other conditions in which personality trait adjectives were rated in terms of Self vs Best Friend, Self vs Bill Gates, and Best Friend vs Bill Gates. He used a blocked-design fMRI paradigm, where non-personality and personality trait adjectives were rated as to whether they applied to themselves or other. The four hypotheses were as follows:

(1) Self conditions would show a different pattern of brain activation from those shown by Best Friend (i.e., close other) and Bill Gates (i.e., far other) conditions; (2) our data should exhibit a fair degree of distributive performance by the brain in responding to these attribution tasks; and (3) the resulting patterns of activation should show some overlap with structures normally involved in preparedness to action (motion). In addition, (4) the Best Friend condition would also differ from the Bill Gates condition.

The study found that several areas of the brain were active when doing the tasks related to ‘Self’ and Best Friend. In support of the first hypothesis (1), there was very significant differential activation in BA 31 (covering part of posterior cingulate gyrus and the medial parietal), and the substantia nigra. There was significant activity in the right and left portions of BA 23, and the caudate tail. In a lesser degree, there was some activity in the BA 10 and the thalamus. There was also greater activation in BA 24, particularly the anterior cingulate cortex, in Self-Bill Gates condition compared to the Best Friend-Bill Gates condition. With these results, there is different brain patterns shown by Best Friend and Bill Gate conditions. The contrasting results found also support the second hypothesis (2), and indicate that a large number of distributive structures throughout the brain are used when doing a self-attribution task.

In support of the third hypothesis (3), he found a large amount of activation of the substantia nigra (key stricture of basal ganglia for action), in addition to the activation of the caudate nucleus of the basal ganglia. These areas in the brain are known to be crucial to the process of movement, and thus an overlap with these structures supports their hypothesis.

In support of the fourth hypothesis (4), the greater activation of BA 24 in comparison of Best Friend vs Bill Gates condition and the Self-Bill Gates condition points to show that humans strongly identify with those you are close to us, and less strongly with ourselves.

The results displayed that the brain areas that we use for thinking about ourselves may also be used for thinking about those who are important to us. The fact that there is this relationship with multiple parts of the brain being active during both goes to show that there is an association between the two, furthering to suggest that one area in the brain nor one unified mechanism is not responsible for the self. The results also support the evolutionary expectation of a connection between self and the preparedness for action. The activation of key areas in the basal ganglia and the differential activation of BA 31 by the self-conditions in contrast with the Best Friend conditions in this study, further support the idea of personality being a product of the unconscious self.

Future work

From the results seen in Munevar’s study, there are several implications for the future progress of this theory. Since the study had a limitation of gender impacting the results of the conditions of Self vs Best Friend and Best Friend vs Bill Gates, further research should be done that classify results of fMRI by each gender. Another positive direction this study points to is by studying brains with deficits in activation of the anterior cingulate that bring problems when identifying self from non-self. This problem is prevalent in mental disorders such as schizophrenia, autism, and late-stage Alzheimer’s, where the ability to differentiate self vs other is compromised. Further research should use the results of Munevar's study and continue on to dissect the paradoxes and problems of traditional conceptions, while focusing on the evolutionary biology of the brain. Overall, the research done on the Evolutionary Theory of Self is promising and provides fruitful insight to the possibility of discovering new conclusions on what we know about the self.

References

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