Book Review: Morality and Evolution

How human beings make moral decisions is still largely unknown. Nowadays researchers are studying moral judgment and/or reasoning in different ways: neuro-imaging, evolutionary psychology, studying patients with deficits, computer simulations, etc. This book is a collection of essays discussing the relationship between morality, brain function and evolution, seen from various angles. The Moral Brain consists of an introduction, in which the editors explain the history of research in this area and some recent developments, and ten chapters about specific topics, which will be summarized in this review before some general comments. The chapters are not numbered.

According to Glenn and Raine in the first chapter, “The immoral brain,” morality developed in humans because cooperation had survival value. People with psychopathy cooperate less and they are therefore an interesting group of people to study ¹ . The authors mention how there are differences between people with psychopathy and normal controls in various brain regions, such as the medial and ventral prefrontal cortex (including orbitofrontal cortex), angular gyrus, posterior cingulate and the amygdala and how each of these regions has been associated with moral judgment in neuroimaging studies. However, there are also regions such as the hippocampus which show abnormalities in people with antisocial behavior but no activation in normal people when performing moral tasks.

Cooperation with other human beings has been a successful evolutionary strategy, but psychopathy could be an alternative evolutionary strategy, according to Glenn and Raine. People with psychopathy tend to have more sexual partners and not to invest heavily in their children. This strategy might well increase reproductive success as long as there are not too many people in a particular population are doing it ² .

The authors also refer to a study of their own group showing more than 20% increase in pre-frontal white matter in pathological liars compared with both antisocial and normal controls (Yang. et al., 2005). In a neuroimaging study comparing students (i.e. a non-clinical population) scoring higher and lower on a psychopathy scale, students scoring higher on the psychopathy scale showed less activation in the orbitofrontal cortex when the person they were playing with cooperated in the prisoner's dilemma game and less amygdala activation when the person they were playing with did not cooperate (Rilling et al., 2007). All these findings suggest a biological underpinning of criminal behavior in at least some people and, if confirmed, it does have consequences for the criminal justice system.

In the chapter, “Extended attachments and the human brain: Internalized cultural values and evolutionary implications,” Moll and Oliveira-Souza discussed their ideas about extended attachment, i.e. not just attachment to parents, partner and children but also attachment to symbols, cultural objects and abstract ideas. According to them this extended attachment might well have played a major role in fostering cooperation.

The authors claim that extended attachment is a unique human ability and that it is realized by various parts of the brain working together: the prefrontal cortex (abstract knowledge and knowledge of events), the temporal neocortex (social knowledge) and the limbic system (basic emotional motivational states). They mention how in humans certain limbic structures evolved together with cortical networks, such as the septal nuclei, and that during human evolution it was not just the neocortex which evolved. Moll and Oliveira-Souza hypothesized that this extended attachment could have been beneficial for in-group social cohesion and indirect reciprocity. They do acknowledge that introspectively the warm glow people experience when helping somebody in need differs from doing something based on a sense of duty but their hypothesis is that brain attachment systems are involved in both.

In the chapter, “Neuro-cognitive systems involved in moral reasoning,” Blair discussed his model of multiple moralities. According to this model, there are at least four partially separate systems in the brain, each dealing with a different form of social rule processing, namely care-based, reciprocity, social convention and disgust based, which are lumped together in the cultural concept of morality. Blair emphasized the neuro-cognitive basis of care-based morality, and he described his own Integrated Emotions System model (IES), consisting of an emotional learning system mediated by the amygdala and a decision making system mediated by the medial orbital frontal cortex. With the amygdala people learn that specific actions are bad, if these actions are associated with the victim's distress/sadness/fear. People with psychopathy do not respond to distress in others or sad and fearful faces, probably because of some problem with amygdala mediated stimulus response learning. There is a second system which processes expected reinforcement. If one sees distress in others, one “knows” via this system located in the prefrontal cortex, that one will get an unpleasant experience. According to Blair neuroimaging studies regarding care-based morality have consistently shown activation of the ventro-medial prefrontal cortex and to a lesser extent in the amygdala.

Research into reciprocity has been quite limited but unlike domain theorists such as Turiel, according Blair, it is a separate domain and not part of care-based morality. This is different from the previous chapter by Moll and Oliveira-Souza, who claim that extended attachment would a mechanism for both. Disgust is a separate system according to Blair, originally associated with food avoidance. Disgust facial expressions like sad, angry or distressed faces can act as reinforcers, convey distaste and are encouraging conspecifics not to eat similar things. At brain level there is activation in the insula and the putamen in neuroimaging studies. People can also develop distaste for other actions, including violation of moral norms.

Blair briefly discussed his own model of Social Response Reversal for conventional norms, such as wearing wrong clothes or speaking in a classroom without permission from the teacher. These conventional transgressions are considered to be bad because of their disruption of the social order. Blair departs here from some other researchers in the field by claiming that affect does play a part in conventional norms (contra, for example, Nichols, 2002), especially but not exclusively anger. He also stated that social conventional transgressions are particularly forbidden in the presence of higher status individuals.

Blair gives an extensive overview of possible proximal mechanisms of moral behavior. Not all the behavior discussed by Blair would be considered moral though. It is problematic that there is no consensus what moral behavior is. Wearing wrong clothes, a classical conventional transgression, will under normal circumstances not be considered a moral problem by ethicists.

In the chapter, “Empathy and morality: Integrating social and neuroscience approaches,” Decety and Batson discuss how, when people perceive others in pain, the same mechanisms are activated as when they are perceiving pain themselves. They discuss the study by Singer et al (2004) whereby the anterior insula, the rostal anterior cingulate cortex, brainstem and cerebellum were activated by the participant receiving a pain stimulus but also by the partner receiving a painful stimulus, while activation in the posterior insula and caudal anterior cingulate cortex only occurred when the participant received the painful stimulus himself.

Decety and Batson argue that a distinction between self and other is necessary for moral behavior. Seeing somebody in pain can cause compassion but also personal distress. Reducing personal distress can lead to running away from the situation and declining to help. Decety and Batson end their chapter by discussing research from Batson, Klein, Highberger, and Shaw, (1995) whereby higher empathy was associated with participants being less fair.

In the chapter, “Moral judgment and the brain: A functional approach to the question of emotion and cognition in moral judgment integrating psychology, neuroscience and evolutionary biology,” Prehn and Heekeren argued in favor of cognition in studying moral judgment. They do not claim that moral intuitionists such as Haidt (2001) who claimed that most reasons people give for their moral choices are post hoc justifications are incorrect, just that they do not provide the whole picture. They also mention how contrary to common belief cognition and emotion are not realized in completely independent separate brain circuits, subcortical structures in the limbic system are also crucial for some cognitive processes, such as hippocampus for memory.

Using neuroimaging techniques Prehn and Heekeren compared moral violations and grammatical violations. For example: comparing “he smashes the window” (moral violation) versus “he look at out the window” (grammatical violation). This experiment showed activation in the ventromedial prefrontal cortex and the posterior superior temporal sulcus for moral violations. In a follow-up experiment Heekeren et al. (2005) compared moral and grammatical violations and bodily harm (2 × 2 comparison) and found rapid response times combined with decreased activity in the temporal poles during trials with a bodily harm stimulus. Prehn and Heekeren, interpreted these findings as more intuitive and automatic processing with emotional stimuli at the expense of more in depth processing.

There are individual differences in responses to certain tests such as the Moral Judgment Test. Participants who scored higher on the Moral Jugdment Test had less activation in the left ventromedial prefrontal cortex, the left posterior superior temporal sulcus and right dorsolateral cortex (Prehn et al., 2008). They interpret these findings by stating that people scoring higher on the Moral Judgment Test are probably more efficient. Prehn and Heekeren end their chapter by making some reference to evolution and argue that different psychological processes have been selected for, some of which give a quick decisions, others do not. However, unlike some other authors who take a descriptive approach Prehn and Heekeren argue that ideally humans should apply “a certain moral orientation in a consistent and differentiated manner in varying social conditions.”

In the chapter, “Moral dysfunction: Theoretical model and potential neurosurgical treatments,” De Ridder, Langguth, Plazier and Menovsky discussed possible interventions from a neurosurgical perspective. They explained that four steps are necessary:

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  establishing that specific behavior is the product of activation or deactivation of particular brain circuits,

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  visualizing these brain circuits via neuroimaging,

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  modifying the function of these circuits for a limited time period with, for example, Transcranial Magnetic Stimulation or selective amytal injection, and

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  finally, implanting electrodes in the brain to modulate the working of these areas.

Currently, deep brain stimulation is offered to sufferers from Parkinson's disease whereby electrodes are implanted in the brain to prevent a tremor. This does not cure Parkinson's disease but makes some disabling symptoms less severe. Similarly treatment of antisocial personality disorder and/or pedophilia might be possible in the future, but antisocial behavior and pedophilia are probably be caused by a variety of problems in brain circuits. A specific circuit for intervention has not been identified yet, contrary to Parkinson's disease, so treating people will be experimental. The authors mention that deep brain stimulation will not be risk free but conclude that treating people who have committed serious crimes is acceptable.

In the chapter, “Does it pay to be good? Competing evolutionary explanations of pro-social behavior,” Veelen provided a general introduction into economic models for altruism, reciprocity, indirect reciprocity and punishment. The key question is how it has been possible for moral behavior to evolve during evolution, given that for the individual non-moral behavior is often advantageous and punishment costly. He explained how economic models can test evolutionary explanations for altruistic behavior such as individual selection, kin selection, sexual selection and various forms of group selection.

Veelen emphasized the importance of precise definitions and he mentioned how sometimes more than one evolutionary process could explain certain behavior. The difficulty is that, if altruistic behavior is explained via kin selection, one could describe it as altruistic (at least from the point of view of the person) but, if one explains it via sexual selection, it is not altruistic but enhancing one's own chances of reproduction. Although economic models of evolution can be useful, they cannot predict behavior at the moment, let alone explain why certain brain areas are involved and there is still a big gap between findings from economic modeling and brain scanning.

In the chapters, “How can evolution and neuroscience help us understand moral capacities?” and “Runaway social selection for displays of partner value and altruism,” Nesse described how humans are inclined to judge others in terms of right or wrong, using their intuition. However, intuitions differ and there is disagreement. Altruism was explained, according to Nesse on the basis of kin selection and mutualism, but there are some difficulties, because humans also help non-kin. He refers to the work of West-Eberhard (1979), who claimed that social skills could be developed via selection similarly to the peacock's tail. But unlike with the peacock's tail fitness benefit would not come from being chosen as mate but from being chosen as social partner. Generally, people who are able to obtain better or more partners will have a selective advantage because they will have more resources for reproduction. Nesse argued that social selection is a possible explanation for human capacities for altruism and third party punishment.

Social selection is natural selection whereby fitness is influenced by the behavior of other individuals and according to this description sexual selection is a subtype of social selection, namely selection determined by partner choice. However, selecting a partner to exchange goods is also a form of social selection. Domestication of animals in Nesse's terminology is a form of social selection, because dogs became the way they are, because their ancestors were chosen by humans, i.e. another species. Humans themselves have been domesticated by preferences of other humans, which is a unique way of looking at human evolution.

In the chapter, “The evolved brain: Understanding religious ethics and religious violence,” Teehan started by describing how the human brain generates religious experiences, e.g. Persinger's study how electro-magnetic stimulation of the temporal lobes gave people the experience of a “presence.” Teehan asserted that finding anatomical and neurochemical correlates of religious experiences is only part of the explanation and continues that adding an evolutionary perspective emphasizing inclusive fitness (i.e. gene reproduction) and indirect reciprocity is essential.

According to Teehan religious experience and doctrine support evolved moral mechanisms. Sometimes, religious views are immediately obvious from an evolutionary point of view, e.g. Moses instructions to spare the virgins among Midianite prisoners. However, often certain religious rules, ideas and convictions need to be clarified from an evolutionary perspective in an indirect way. Prevention of cheating is important in societies with reciprocity within particular groups. People are less likely to cheat, if they know that there is an agent who will always be aware that they are cheating. Many religions have an omniscient higher power.

Recognizing group members is essential and Teehan described how Jewish and Christian religious rituals made it easy to recognize other members of the same group. Furthermore, costly rituals also show commitment. Arguing from evolutionary psychology, like Teehan is, the main role of religion seems to be to support moral behavior, such as cheater detection and creating cooperative groups.

Teehan does accepts that some religious teaching, e.g. the Christian doctrine “love your enemies” seems difficult to explain from an evolutionary perspective. One could state that religions can also display an element of moral creativity. However, if one looks in practice what has happened with Christianity, the inquisition, crusades, etc. the doctrine has not been followed.

In the final chapter, “An evolutionary and cognitive neuroscience perspective on moral modularity,” De Schrijver discussed the massive modularity hypothesis and recent findings in cognitive neuroscience and he asserted that evolutionary psychology claims that much of the structure and function of the brain is innate, that functions are embodied in domain specific modules and that the brain consists of many of such modules. Cognitive neuroscience emphasizes learning and accepts the role of more general higher cognitive processes such as reasoning while denying that there are specific modules. Both views can to some extent be reconciled by stating that modules can also exist as psychological functions and that a specific anatomical location is not necessary. De Schrijver is the only author who discusses some of the previous chapters, mentioning for example how Prehn and Heekeren are more in favor of the cognitive science approach emphasizing the importance of general mechanisms and Blair emphasizing the importance of learning. The overall conclusion is more or less standard, namely that evolutionary psychology can develop hypotheses, which then need to be tested by cognitive neuroscience.

The collection of essays is very interesting. One chapter was a reprint from another publication (one of Nesse's chapters) and for some chapters there is a considerable overlap with other publications, e.g. chapter by Glenn and Raine has overlap with Raine and Yang (2006) and Blair's chapter with Blair, Marsh, Finger, Blair, and Luo (2006). Although most of the information can probably be found elsewhere, the book does cover a wide range of topics and it is convenient to have the articles combined in one volume. Given the price, buying is probably only an option for libraries.

Each chapter can be read on its own but the disadvantage of this is that there is considerable overlap (for example, kin selection explained by Veelen pp. 191–192 and Teehan pp. 236–237). With the exception of the introduction and the last chapter there are rarely cross references between the various chapters, and generally the authors do not respond to each other. Personally, I would have been interested in economic models for frequency dependent selection of psychopathy but this was not discussed in the relevant chapter by Veelen.

There are topics not mentioned, e.g. Prehn and Heekeren briefly discuss Kohlberg's stadia of moral development but there is no separate chapter for moral development. There have been quite a number of studies showing that emotional experiences influence moral judgment (Schnall, Benton, and Harvey, 2008; Wheatley and Haidt, 2005) but this line of research is not discussed in a separate chapter. There is a chapter for neurosurgical interventions but other forms of treatment such pharmacological or psychological interventions are not discussed. However, given the vast literature published about morality and brain function, it is probably unavoidable that there are topics missing.

There are also more fundamental problems not discussed. Chapter authors describe a dazzling number of neuroimaging experiments, but difficulties with interpreting neuro-imaging data are hardly mentioned. Prehn and Heekeren briefly explained that in neuroimaging the substraction technique is used. The idea of the substraction technique is to have one task with a moral component and another very similar task without a moral component and then look at differences in brain activation via fMRI and conclude that areas which are activated for the moral task but not for the control task must be the localization of moral judgment. Prehn and Heekeren asserted that one has to compare the different tasks thoroughly by looking at reaction times, error rates etc. However, problems remain, because it is difficult to determine whether the tasks are exactly similar. There are more problems with interpreting fMRI data. There is individual variation in histology (Zilles and Amunts, 2010). Furthermore, the way how images are analyzed varies between laboratories and is hotly disputed (Vul, Harris, Winkielman, and Pashler, 2009). Another factor is that at the current level of resolution of fMRI scans similar locations are associated with very different tasks and this could be a problem with sensitivity but it has also been argued that the same neurons are used for different tasks (Anderson, 2010).

Another problem which could have been explored more is whether the current data and findings should only be used descriptively or also normatively. Nesse mentioned that one could argue that rape might have been evolutionary advantageous but that this does not make this behavior acceptable, in other words what has been selected for is not automatically good in a moral sense, but it remains unclear what the norms should be. Prehn and Heekeren argue that integration of emotional and cognitive influence in a consistent manner should be the norm, but this is difficult to defend from an evolutionary point of view. Human morality is not based upon what would be most successful for procreation, but the big question what norms should be used and why is hardly mentioned in the book.

What the book does make clear and what was mentioned by a number of authors, is that there is still a huge gap between hypotheses based on evolutionary theory and investigating proximal mechanisms. Human beings have been selected for at least some behavior we classify as moral, but we do not know much more despite the extensive research currently going on.