ABSTRACT
How a species interprets the world around it will always rely upon the unique nexus of selective pressures encountered during its evolution. For the evolutionary scholar working from an adaptationist perspective, it makes little sense to ask whether one species is “smarter” or “more intelligent” than another. Natural selection optimizes every species for one thing: to capitalize on biological and psychological traits in a way that leads, over time, to genetically profitable outcomes. The brain of each individual must therefore function over time to maximize reproductive fitness in response to specific ecological challenges. In the case of human ancestors, one very real challenge was other people. In the present chapter, we present the case that the unique social selective pressures encountered by our ancestors may have led to the evolution of our species’ religious sentiments. More specifically, we show how one particular cognitive capacity – the capacity to attribute mental states to other natural agents – was co-opted by natural selection when it was extended to reasoning about the minds of supernatural agents. Like any other product of natural selection, brains are subject to what evolu-
tionary theorists refer to as an “environment of evolutionary adaptedness” (hereafter, EEA). John Tooby and Leda Cosmides define an EEA as “the statistical composite of selection pressures that caused the design of an adaptation” (Cosmides and Tooby 1997). Since no two species shared exactly the same ancestral climatological, geographical, biological, and social pressures during their evolution, selection pressures vary tremendously. An individual disadvantaged by a cognitive architecture unable to cope with these pressures would quickly find their genes doomed to extinction. Fortunately, the brains of every species living today did find a way to navigate the
hurdles of their respective EEAs. The challenge for cognitive scientists is to respect both the convergences and divergences between species that emerged due to these separate arenas of competition. By observing the psychological and behavioral similarities – and differences – between two species to infer shared – or distinct – selection pressures
in their ancestral pasts, fresh light can be shed upon the unique abilities and limitations of each. It therefore should come as no surprise that great apes have been an important
focus of research for scientists interested in the evolution of the human mind. For example, chimpanzees and human beings share a common evolutionary ancestor that lived approximately 5-7 million years ago. If we were to compress the 4.5-billionyear age of our planet into one calendar year, chimpanzees and humans split roughly around noon on December 31. Although not identical, much of our respective mental architectures emerged from the very same EEAs. This similarity is why our exploration of non-human cognition will focus upon
our closest genetic relatives. Why? Because it is precisely this intimate genetic and evolutionary relationship that makes chimpanzees outstanding subjects for attention, not only to better understand our own place among life on Earth, but also to unravel the fascinating workings of the chimpanzee mind itself. Understanding how the brutal calculus of natural selection produced two species similar in so many ways, yet utterly different in others, is of inestimable value to both chimpanzee and human alike.
In 1970, psychologist Gordon G. Gallup developed an experimental test that literally changed the way simians across the world viewed themselves (Gallup 1970). Gallup was interested in determining whether species other than human beings were able to think of themselves as selves – that is, whether they have a conception of their existence apart from that of others. While Gallup’s chimpanzee subjects were put under a harmless general anesthesia, a red dye was applied to a place on their body visibly accessible only in a mirror, such as their eyebrow ridge. Upon reawakening, the chimpanzees were presented with a mirror and their reactions to the red dye recorded. The chimpanzees quickly recognized the anomalous nature of the red dot and touched the point on their face where the dot had been placed by the experimenters. The conclusion drawn by Gallup was that the chimpanzees could only react in such a manner if they understood that the reflected image was, in fact, an isomorphic representation of themselves. Otherwise, he reasoned, they might touch the mirror itself or react to the image as if it were another animal, perhaps a pitiably strange chimpanzee with a blemish on its face. The results were shocking to many. If the results were, in fact, being
properly interpreted, the implications would transcend ethological and psychological boundaries. Human uniqueness had long been a hallmark of philosophy, theology, anthropology, and linguistics, to name but a few disciplines. Thus the finding that an animal other than Homo sapiens could “recognize” itself in a mirror – and thus, many assumed, they must possess a “self-concept” – posed a challenge to traditional ways of thinking about humanity’s place in the world. For example, advocates of animal rights argued that if chimpanzees understood themselves as individuals, then should they not also feel pain and suffer as humans do too? Years of refinement and continued experimentation with Gallup’s basic
design have continued without pause. Dozens of species have been tested for mirror
self-recognition (hereafter, MSR). Chimpanzees repeatedly have been shown to pass the test. They are not alone, but they remain in select company. In a 2008 review of the literature, primatologist Frans de Waal concluded that “strong indications for MSR have been obtained only for the four great apes, bottlenose dolphins, and Asian elephants” (de Waal 2008). Repeatable results like these have led to wide citation in academic journals and popular accounts of scientific research. In fact, for many readers of this volume, the MSR test may be their only acquaintance with the field of non-human cognition. However, the MSR test is not without its critics. Neuroscientist V. S. Ramachandran
has pointed out that human patients with certain neurological impairments can pass Gallup’s test while absolutely unaware that the person in the mirror is them. They make no identification of “self” even though they move towards and immediately recognize the experimental marking (Ramachandran 2007). It is also possible that simple proprioception is at work. Proprioception refers to the sense an organism has of where its body and bodily parts reside in space. Movement towards the spot of red dye could be an unconscious behavior wholly unrelated to self-awareness. But, given its implications for our understanding of human social evolution, let us
assume that the MSR test does demonstrate that chimpanzees see themselves as selves. This would, as we have acknowledged, be of enormous significance. To know oneself as an individual is no doubt of great selective value. Yet primates are first and foremost creatures who have lived, with few exceptions, in groups for tens of millions of years. Regardless of how chimpanzees or humans conceive ourselves individually, as primates we are embedded within a complex web of interaction with conspecifics that must be navigated by sophisticated cognitive modeling. This view has been most notably articulated by British evolutionary biologist Robin Dunbar (1998). Dunbar points out that our ancestors lived in situations where getting along with others was paramount to survival. There are enormous advantages available to the individual living harmoniously with others: access to food, protection, and warmth being paramount among them. Efficient cooperative action translates into greater reproductive fitness and opportunities to pass along more pro-social genes. The problem is that the social fabric is under constant threat from defectors and
cheaters who would undermine the advantages of group living for personal gain. Their detection is of the utmost importance. Since the duplicitous rarely announce their intentions to cheat and offend, an individual needs access to the inner thoughts and intentions of those around them. Furthermore, over evolutionary time scales, as cheaters become easier to detect, they “raise their game” and embrace more subtle and complex methods of deception. Those who would censure the cheater must then become better at detection, fueling an ever-escalating cognitive arms race. For our ancestors, being content with “knowing thyself” would have been a road to oblivion.
