Finally, we are recipients of a brain that does marvelous and strange things. Only a very small percentage of its many possible operations have been addressed in this chapter. It’s unlikely that the brain has evolved the way it has on purpose. More probably it is the product of multiple influencing factors stretching back millions of years. This raises the possibility that an informative approach to exploring these marvelous and strange things is to consider their possible evolution. That is where we are headed.
Greg’s e-mail was encouraging.
I like this chapter, it’s very informative and need I mention that it will invite criticism. Details to follow.
Best,
Greg
Our e-mails read this way:
Dear Greg,
Thanks for your comments on the Awareness chapter. I was also pleased with it. And yes, it will invite comments.
Turning to other matters, things are fine and as usual here. Have the next chapter in draft. Do you have time to comment on a half-page summary of my approach?
Hi Michael,
Still very busy with teaching and, as you might suspect, more time with Francesca. Of course, send your summary.
Dear Greg,
My approach runs something like this:
The brain systems discussed in the awareness chapter as well as an immense amount of data from history, psychology, behavioral observations, and medical science need to be given a framework.
Evolutionary theory seems the obvious choice. Why? In part because it’s the framework most consistent with my focus on the brain rather than the “mind.” In part because the brain systems and the brain’s bias to believe didn’t appear overnight. They are the likely consequences of multiple past events and selection processes. Presumably many of the systems were selected because they provided an adaptive advantage, which they may still do, although this is arguable for some systems.
Details of past events possibly influencing selection along with their consequences would follow.
Your thoughts, or do you want me to guess?
Hi Michael,
One of the reasons I enjoy our friendship is because we think differently. And we certainly do when it comes to evolutionary theory. Perhaps you are comfortable with it, but I’m not. I’ll grant that it’s the best theory around to explain a host of points you’re discussing. I’ll also grant that there is no compelling alternative theory of which I’m aware. Still, I’m uneasy. It’s over-weighted in speculation relative to the available evidence and many of its ideas can’t be tested. From what I can see there are internal inconsistencies, which often lead to different ways of making sense out of the same evidence. To me, this suggests that the theory lacks precision. Put another way: yes, points can be explained but with what degree of certainty?
I’d like to be more enthusiastic. But let me be clear on one point: I can’t argue that there is a better framework. If you proceed as your summary suggests, which I suspect will happen, I will be delighted to savor your effort.
Best,
Greg
As usual, Greg had a point.
WORDS OF CAUTION
Insights dealing with ways in which beliefs and divides might have evolved as preeminent features of the brain may emerge from attempts at reconstructing their histories. This and the following four chapters engage in this task.
But first, some words of caution.
Efforts to reconstruct the past, especially the very distant past, are perilous and beset with myriad potholes. Evidence that might nail down critical contexts, events, or behavior frequently is unavailable. Theoretical biases may overvalue specific areas of inquiry and ignore others. For example, among paleoanthropologists, there is a notable absence of inquiry about the reproductive strategies of our ancestors.1 Then there are disagreements among scholars over the authenticity and interpretation of findings. There are also vexing and unavoidable asymmetries in evidence. For example, chemical methods used to date the past age of physical evidence (pots, dirt) and biological evidence (bones, hair, DNA) can be quite accurate. However, very little may be known about the behavior of those living at the times that coincide with the chemical dates.2 Thus, divides often are indeterminate when trying to tie together chemical-based evidence and behavior.
Another factor is that research reports documenting the discovery of ancient humans and other hominids along with reevaluations of previously reported findings are published weekly.3 In turn, today’s reconstructions may be obsolete tomorrow. An example deals with the morphology of Homo erectus, one of our ancestors, which is currently undergoing review as a result of new evidence and improved analytic techniques.4 Recently, the discovery of remains of modern-day humans living in China one hundred thousand years ago has been reported.5 Few scholars suspected this possibility ten years ago. Fifteen years ago, few experts would have suggested that at least twenty-five different hominid species have evolved during the past six million years.6 Nor, until recently, did anyone predict that approximately 1.2 million years ago, the ancestors of today’s humans were possibly an endangered species with fewer than twenty-six thousand individuals capable of breeding.7
REVERSE ENGINEERING
Much of reconstruction involves reverse engineering. This amounts to extrapolating back in time using present-day findings and methods. Studies documenting the rate of genetic change from specific periods in the past to the present are examples.8 Or the same brain chemicals may be found among today’s humans and chimpanzees, which split from a common ancestor millions of years ago. A reverse-engineering inference might be that the chemicals were present in their common ancestor prior to the time of the split. The inference could be wrong, of course. The chemicals might have evolved independently in each species following their split. Nonetheless, attempts at reconstruction often leave reverse engineering as the best—if not the only—currently available option for reconstruction.
A TAKE ON RECONSTRUCTIONS
Given less than the desirable amount and specificity of evidence, reconstruction can be approached in two ways. One approach is to forgo the exercise and avoid inciting skepticism and criticism among readers. A second approach is to try to develop a plausible scenario with the aim of stimulating further research and interpretation. I have adopted the second approach. That said, it needs to be affirmed strongly that no two individuals writing on the evolution of belief and divides would develop similar accounts.
The reconstruction begins with a selective overview of events, contexts, and behavior that might have been critical in the evolution of belief and divides. It then turns to the pivotal functions of language, observation learning, emotion, and cognition. The chapter closes with a discussion of the migration of Homo sapiens out of Africa and the dispersion of beliefs.
BONES AND TOOLS
Belief and divides didn’t appear overnight. Multiple requisite conditions and events, some dating back millions of years, presaged their appearance.
There are skulls and bones of human ancestors that are at least 4 million years old.9 Bones used for tool-assisted consumption of animal tissue may be older than 3 million years.10 Single-edge cutting tools—“Oldowan choppers”—were in use 2.6 million years ago. Hand axes have a history of at least 1.6 million years. A greater-than-2-million-year history of tool making suggests that the craftsmen of that period had mastered the techniques of tool construction, had an appreciation of the utility of the tools they constructed, and took care to remember where they stored them. A reasonable inference is that capacities for remembering, believing, predicting, and constructing tool kits for practical matters were present and in use.
GENES AND BRAIN CHANGE
The progressive speciation of our own species, as well as other humanoids, is a history written in part in changing genetic-behavior associations. For example, aggressive facial patterns, defensive forelimb movement, and reaching-and-grasping movements appear to be largely “hardwired” in the primate brain and species-universal in form.11 Such findings hin
t at their ancient origins as well as their adaptive value through stages of species change.
Genetic changes also altered the physiology and functions of the brain.12 A possible case in point is the brain chemical dopamine. Well before the first tools were made, it’s likely that dopamine influenced the intensity of the emotions of pleasure, reward, and displeasure.13 Or consider the prefrontal cortex. Today it is integral to cognitive control and harbors capacities to coordinate thought with action reflecting personal goals. No doubt it was present in the distant past, although in a less sophisticated form compared to today.14 The integration of physiology with brain function is also likely: it is the brain’s frontal cortex and midbrain where dopamine largely exerts its influence on emotion and cognition. A similar story applies to the hormone oxytocin. It increases feelings of trust when its levels are elevated.15 Genetic change leading to conditions that alter its brain levels may have been instrumental in the early moments of extended socialization.
Complementing hardwiring are partially innate capacities that were refined in response to gene-brain-environment interactions. Examples include behaviors and capacities that process environmental and social information using touch, visual, olfactory, and auditory modalities, possibly also associational learning and episodic memory.16 The refinement of these capacities and behaviors is likely to have correlated with an increase in the size of semipermanent social groups along with improved strategies for mastering novel environments and challenges. Structural changes in the brain would follow these developments.17
Then there is novel behavior, that is, behavior that is describable by its form and definable by its uses but that is not species universal in form. This is behavior that is not the direct result of natural selection but that emerges when existing systems or capacities combine in new ways in response to social and physical environment options.18 The multiple skills required for constructing single-edge cutting tools, engaging in cooperative hunting using coordinated strategies, and constructing living structures are examples.19 The dates when these behaviors first appeared are unknown. But clearly, when they did appear, our ancestors were poised to exploit their potential. They would continue to do so for thousands of generations to come. Thus it is not surprising that a large percentage of today’s human-behavior repertoire is composed of novel behaviors. Driving an automobile in reverse and playing the piano are examples. That such behavior can influence the structure and function of the brain as well as subsequent evolution is suggested by studies showing that mastering reading results in changes in the cortical networks for vision and language.20
There is yet another chapter to this history. Genetic, environmental, and experience differences meant that there would be individual differences in personality, emotional makeup, mate and lifestyle preferences, physical skills, food tolerance, and capacities for processing information.21 Such differences are compatible with the view that multiple and very different beliefs were present in the past, much as they are today. An unavoidable implication of these points is that no two brains were likely to have believed or managed divides exactly the same way.
Despite these many contingencies, the net effect for our ancestors was a gradually expanding understanding and mastering of their personal and social worlds and their physical environments. These developments would serve as the matrix for the emergence of culture, increasingly complex social organization, and a continuing diversity of beliefs.
CULTURE
Culture can be defined as the beliefs, social forms, and material traits of a group that comprise a body of knowledge and ritual that is transmitted across generations.22 There are various estimates for its starting date, although the notion of a starting date is misleading. Culture didn’t just appear at a specific moment in time. It evolved gradually over millennia. Estimates vary as to when there is clear evidence of its presence. The date of eight hundred thousand years ago has been suggested.23 Some scholars would place it farther back in time—this would be consistent with the evidence of the far earlier presence of tools. Others favor a more recent date. The divide is indeterminate and influenced by how culture is defined. I will adopt eight hundred thousand, plus or minus two hundred thousand, years as a reasonable estimate: during that period, members of an as-yet-to-be-identified hominoid species, whose artifacts suggest the presence of culture, settled in northern Europe.24
Culture is a product of people living together, interacting, and sharing information. Mothers and their offspring were likely the first to do so. The probable next step was the formation of small groups composed of family members and then, eventually, more distant relatives. As group size increased, so would the collective knowledge of groups. Perhaps, too, these events were associated with occasional inbreeding with now-extinct species along with a glimmering of concern about genetic continuity. Current genetic evidence is consistent with the cross-species breeding possibility.25
Culture presupposes the presence of a social brain, that is, a brain that can meet the computational requirements of group living. These include pair bonding, processing a diverse array of one’s own and others’ emotions, such as empathy, anger, and pleasure, and recognizing and tolerating individual differences in goals, belief, and action.26 The social brain also means collecting and interpreting information using multiple brain channels, including those that process posture and facial expressions and auditory information, such as voice tone and voice signatures. Each of these channels served as a source of evidence that likely fostered various forms of social cooperation, including direct and indirect reciprocity, coalition formation, altruism, sensitivity to fairness among group members, and beliefs about how best to behave.27 There were also likely effects on the brain. For example, among adult humans, amygdala volume positively correlates with the size and complexity of a person’s social network.28
An interesting possibility is that groups composed of individuals with similar attributes, such as personality type, food tolerance, and brain levels of the chemicals dopamine and serotonin, sought each other’s company and migrated together. This would represent an example of the founders effect: a subset of a population with specific genetic characteristics finds itself isolated from other groups and a larger gene pool.29 At times, isolation appears to be followed by the rapid alteration of attributes. This is one way to read data documenting the genetic, behavioral, and belief differences among groups that, for generations, have been isolated reproductively and socially.
Living together invites a division of labor. Some individuals hunt, some raise children; some lead, and some follow. With increased experience, behavioral options and constraints such as preferences for group size associated with different tasks likely became important.30 So too for joint decisions among small groups—in effect, a kind of collective intelligence—which often is superior to decisions made by single individuals.31 But living together also opened the door for social manipulation, such as deception and free-riding.
A social brain further implies that there is a sense of the self, that is, a personal identity that, among other things, permits its owner to engage in social comparisons.32 This sense was likely associated with beliefs such as judging oneself more attractive, brighter, or more skilled than others as well as the development of divides dealing with evidence deemed to justify such judgments.33 Social comparison also has a history.
Beliefs, probably less complex than those of today, were an essential part of these unfolding developments. Yet even during the moments when culture was in its infancy, it is probable that our ancestors had beliefs about such matters as the advisability of certain social behaviors and relationships, raising offspring, hunting, animal behavior, and the dangers of interacting with other groups.
LANGUAGE
The emergence of culture presupposes the development of a shared means of communication for establishing relationships and facilitating group management.34 The origins of human language and near-human speech may date back at least two million years, to the Old S
tone Age.35 Likely early uses were among mothers and offspring as well as craftsmen and hunters who shared their techniques. Whatever the details, language appears to have been a critical facilitator in the evolution of our ancestors. Understanding and exploiting environments and carrying out activities such as group organization, migration, and group defense could follow.36 As with other evolved capacities, language development no doubt underwent thousands of years of refinement punctuated by multiple, small, genetic changes associated with the ability to speak and learn.37
If, as some scholars have suggested, humans evolved primarily to act to survive and reproduce and only secondarily to think, there are implications for language development.38 A preponderance of words and expressions that identified predators and environmental dangers, warned group members of such dangers, and facilitated mating would be expected. Conversely, had humans evolved primarily to think and reason, and only secondarily to act, then thinking and reasoning would be more efficient and responsible for fewer errors than likely was the case in the past and certainly is so today. The lingering effects of this possible early asymmetry may still be with us: we appear to be much better at naming things than reasoning clearly.
An understanding of the evolution of language is far from complete. For example, it is not clear how, after millions of years of evolution, the brain could have the capacities for reading and writing, which began only some 5,400 years ago.39 The fact that researchers currently are looking at communication among nonhuman species with the aim of obtaining insights about language development among early humans is also a sign of incomplete understanding.40 Completing these investigations may require decades. Nonetheless, two points invite comment. In the distant past, culture and language bidirectionally influenced each other much as they continue to do today. And language and belief would become inexorably interwoven.
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