From Nonhumans to Humans
SO FAR, my use of evolution as a navigational guide has been based entirely on genetic evolution. That might suffice for birds, bees, and bacteria, but thinkers throughout history have regarded humans as uniquely different from other species. A common formulation during the post-Darwinian era is that evolution explains the rest of life, our physical bodies, and a few basic urges such as to eat and have sex, but has little to say about our rich behavioral and cultural diversity.
Our quest to answer the question “Does altruism exist?” therefore requires a consideration of humans per se and our distinctive properties in addition to what we share with other species. Fortunately, progress during the last few decades has enabled us to provide an account of human evolution that does justice to our distinctive capacity for behavioral and cultural change, while remaining firmly within the orbit of evolutionary science.
Our starting point is the concept of major evolutionary transitions, which notes that the balance between levels of selection (as defined by multilevel selection theory) is not static but can itself evolve. On rare occasions, mechanisms evolve that suppress disruptive forms of selection within groups, causing benign forms of within-group selection and between-group selection to become the dominant evolutionary forces. When this happens, the groups become so functionally organized that they qualify as organisms in their own right. This concept was originally invoked to explain the origin of nucleated cells and was later generalized to explain the first bacterial cells, multicellular organisms, eusocial insect colonies and possibly even the origin of life itself, as I recounted in chapter 2.
Major evolutionary transitions have three hallmarks. First, they are rare events in the history of life. Group-level selection figures in the evolution of many single traits in many species, as we have seen from the examples in chapter 2, but becoming the primary evolutionary force for most traits in a species is another matter.
Second, major evolutionary transitions have momentous consequences once they occur. Higher-level superorganisms such as nucleated cells, multicellular organisms, and eusocial insect colonies dominate their lower-level competitors (bacterial cells, single nucleated cells, and solitary insect species, respectively) in ecological competition. According to current estimates, eusocial insect societies (primarily wasps, bees, ants, and termites) originated only about a dozen times but currently account for over half of the insect biomass on earth.1 The lower-level units of functional organization are not completely displaced. There are still plenty of bacteria, single-celled nucleated organisms, and solitary insect species on the face of the earth, illustrating the important point that higher-level functional organization is not adaptive under all circumstances. Nevertheless, when an ant colony moves into a rotten log, most of the solitary invertebrate species in the vicinity are quickly displaced.
Third, the suppression of disruptive forms of within-group selection is only partial and not complete. Pure organisms, whose lower-level elements work 100 percent for the common good, do not exist. One of the most important discoveries in evolutionary biology during the last few decades has been to realize how much a multicellular organism is a highly regulated society of cells that is elaborately organized to withstand an onslaught of cheating and exploitation from within.2
Against this background, our distinctiveness as a species can be summarized in a single sentence: We are evolution’s latest major transition. Alone among primate species, we crossed the threshold from groups of organisms to groups as organisms. Other primate species cooperate to a degree, sometimes to an impressive degree, but disruptive within-group competition for mates and resources is still a strong evolutionary force.3 Even the cooperation that does take place within primate groups often consists of coalitions competing against other coalitions within the same group. Our ancestors managed to suppress disruptive forms of within-group competition, making benign forms of within-group selection and between-group selection the primary evolutionary forces.4
The distinction between disruptive and benign forms of within-group selection is crucial. There’s a world of difference between socially dominant individuals in most primate groups, who simply appropriate the best mates and resources for themselves, and high-status individuals in small-scale human societies, who must earn their status by cultivating a good reputation. The kind of social control that suppresses destructive within-group competition but permits and often cultivates group-beneficial forms of within-group competition is part of what the concept of major evolutionary transitions is all about.5
All of the hallmarks of a major evolutionary transition are present in the human case. It was a rare event, happening only once among primates, and the combination of a species that is both functionally organized at the group level and highly intelligent at the individual level is doubly rare, as we shall see. It had momentous consequences. Just as eusocial insects constitute over half of the insect biomass on earth, we and our domesticated animals represent a large fraction of the vertebrate biomass on earth, for better or for worse.6 The suppression of disruptive forms of lower-level selection is only partial and by no means complete. Everyday life and the annals of history are replete with examples of individuals and factions that succeed at the expense of their groups, despite the arsenal of social control mechanisms designed to thwart them. If the cells of multicellular organisms could talk, they would tell stories similar to the ones that we tell each other.
The idea that a human society is like a single body or a social insect colony is both old and new. Religious believers around the world are fond of comparing their communities to bodies and beehives, as I recount in chapter 6 and at greater length in my book Darwin’s Cathedral.7 The founders of the human social sciences also took the organismic concept of human society seriously. As Harvard psychologist Daniel M. Wegner puts it,
Social commentators once found it very useful to analyze the behavior of groups by the same expedient used in analyzing the behavior of individuals. The group, like the person, was assumed to be sentient, to have a form of mental activity that guides action. Rousseau and Hegel were the early architects of this form of analysis, and it became so widely used in the 19th and early 20th centuries that almost every early social theorist we now recognize as a contributor to modern social psychology held a similar view.8
Yet this view was largely eclipsed by a paradigm shift that took place during the middle of the twentieth century that is often labeled methodological individualism. According to social psychologist Donald Campbell,
Methodological individualism dominates our neighboring field of economics, much of sociology, and all of psychology’s excursions into organizational theory. This is the dogma that all human social group processes are to be explained by laws of individual behavior—that groups and social organizations have no ontological reality—that where used, references to organizations, etc. are but convenient summaries of individual behavior.9
This kind of individualism was not restricted to the ivory tower but came to permeate modern everyday life. As British prime minister Margaret Thatcher famously commented during an interview in 1987, “There is no such thing as society. There are individual men and women, and there are families.” I have more to say about individualism in political and economic thought in chapter 7.
Against the background of individualism, the prospect that human societies are like bodies and beehives after all is a paradigm shift of the first rank. Fortunately, we have a rich early tradition in the human social sciences to consult in addition to a more recent literature informed by evolutionary theory.
The functional organization of human groups during our evolutionary past included physical activities such as childcare, food acquisition, predator defense, and trade and warfare with other groups. It also included mental activities, which is one reason that I featured the concept of mentality as a group-level adaptation in chapter 1. In fact, most of the mental attributes that we regard as distinctively human, such as our capacity for symbolic thought (including but not restricted to language) and the ability to transmit learned information across generations (culture), are fundamentally communal activities. This assertion has led to a hypothesis that a single shift in the balance between levels of selection led to the entire package of distinctively human traits, including our ability to cooperate in groups of unrelated individuals, our distinctive cognition, and our ability to transmit culture. I have called this the cooperation came first hypothesis,10 although I now prefer the phrase group-level functional organization came first, to underscore the fact that group-level functional organization need not look like overt cooperation, any more than it needs to look like altruism.
According to this hypothesis, most primate species are very smart as individuals, but their intelligence is predicated upon distrust. Chimpanzees, our closest living relatives, rival and even exceed our intelligence in some respects but have mental deficits that seem strange to us, such as the ability to understand the information conveyed in pointing.11 In some respects, dogs have more humanlike intelligence than apes, because dogs have been genetically coevolving with humans for thousands of generations and apes have not.12 This fact seems amazing to those who think of braininess as a single trait, with humans the brainiest species, our closest ape relatives distant seconds, and dogs somewhere in the middle of the pack. It becomes more sensible when we regard the brains of all species as adapted to their respective environments and our brains as adapted to life in groups whose members could be trusted, for the most part, to act on our behalf. The brains of any species evolve in certain ways in trustworthy social environments and other ways in treacherous environments—hence the outcome that a distantly related species such as the dog can resemble our intelligence more than a closely related species such as the chimpanzee.
Our capacity for symbolic thought that can be transmitted across generations, including but not restricted to language, led to a quantum jump in our ability to adapt to our current environments. Many species form mental relations that correspond closely to environmental relations, such as associating food with a sound immediately preceding the presentation of the food. However, these mental relations are broken as easily as they are formed. Symbolic thought involves the creation of mental relations that persist in the absence of corresponding environmental relations.13 Rats associate the word “cheese” with the food as long as the two are presented together, but not otherwise. In contrast, I could say the word “cheese” to you a million times without presenting cheese, and the mental relation would still persist. Humans even have symbols for imaginary entities, such as “trolls,” that don’t exist in the real world.
The ability to create symbolic relations that don’t correspond to environmental relations might seem maladaptive, but symbolic relations remain connected to the environment in another sense. Every suite of symbolic relations motivates a suite of actions that can potentially influence survival and reproduction in the real world. If we call a given suite of symbolic relations a “symbotype,” then there is a symbotype-phenotype relationship comparable to a genotype-phenotype relationship.14 Moreover, just as genetic polymorphisms at many loci result in a nearly infinite number of genotypic combinations, permutations of symbolic relations result in a nearly infinite number of symbotypic combinations, each with potentially a different effect upon human action. In short, the human capacity for symbolic thought is nothing less than a new system of inheritance.15
Although the concept of symbolic thought as an inheritance system is simple enough to grasp, it is a seismic shift in thinking against various intellectual backgrounds. Darwin knew nothing about genes and conceptualized inheritance as any mechanism that creates a resemblance between parents and offspring. Once genes were discovered, however, they became the only mechanism of inheritance in the minds of most evolutionary biologists and the general public. Inside and outside the ivory tower, say the word “evolution” and most people hear the word “genes.”16 Current evolutionary theory therefore needs to expand to include the concept of symbolic thought as a nongenetic inheritance system.
A different seismic shift takes place for intellectual traditions that are centered on symbolic thought, but not from an evolutionary perspective. Thinkers from traditions such as social constructivism and postmodernism also tend to associate evolution exclusively with genetic evolution, which causes them to regard their own constructs as outside the orbit of evolution altogether. For them, the need to study symbolic thought from a modern evolutionary perspective might take some adjustment,17 yet they have as much to teach evolutionary biologists as to learn from them.
Much is sometimes made of the fact that human behavioral and cultural processes are often directed toward a goal, in contrast to genetic variation, which is not random in the strict sense of the word but is said to be arbitrary with respect to the traits that are selected. The terms Lamarckian and Darwinian are often used to make this comparison, but avoiding historical revisionism is important. Darwin also invoked the inheritance of acquired characters in his effort to explain the nature of heritable variation. Moreover, as Eva Jablonka and Marion Lamb explain in their important book Evolution in Four Dimensions, if Lamarck had been correct, the outcome of evolution would be much the same—there would still be giraffes with long necks, for example. In fact, at least some forms of genetic variation are proving to be directed after all.18
Theoretically, there is nothing heretical or “non-Darwinian” about goal-directed evolutionary processes, because their directed aspects evolved by undirected heritable variation in the past. Moreover, goal-directed processes typically include undirected components. Consider intentional decisionmaking, one of the most goal-directed forms of behavioral and cultural change, which involves explicitly selecting among alternative options with set criteria in mind. The search for options can be either directed or undirected, and the most creative options often come out of nowhere. That’s what brainstorming and thinking out of the box are all about. Evolutionary algorithms have become important engineering tools because having a computer randomly generate options can identify potential solutions better than more narrow goal-directed algorithms. In short, if we regard decisionmaking as an explicit variation-and-selection process, the variation part often benefits from an undirected component.
The selection part of an intentional decisionmaking process is goal-directed by definition, but many selection criteria are possible. Some individuals might select the options that maximize their relative advantage within their groups. Others might select the options that maximize the advantage of their groups, compared to other groups. Others might select the options that maximize world peace or the sustainability of the planet. Which selection criteria come to be employed in any particular decisionmaking process? Another selection process must be invoked to answer this question. In this fashion, current variation-and-selection processes must be explained in terms of past variation-and-selection processes, like peeling away the layers of an onion. In addition to conscious decisionmaking, other directed selection processes take place subliminally, such as our tendency to copy the behaviors of high-status individuals.19 Then there is the raw process of undirected cultural evolution—many inadvertent social experiments, a few that succeed. Even intentional decisions result in variation that is arbitrary with respect to what is selected when they produce unintended consequences or collide with each other.
The most important common denominator for variation-and-selection processes, whether directed or undirected, is that they are open-ended. They are capable of producing new phenotypes in response to current environmental conditions. This is in contrast to what evolutionists call closed phenotypic plasticity, which selects among a fixed repertoire of phenotypes in response to current environmental conditions.20 The best way to appreciate the open nature of human phenotypic plasticity is to step back from the “trees” of the academic literature to view the “forest” of the human social conquest of earth, as E. O. Wilson puts it.21 A single biological species spread out of Africa and inhabited the globe, adapting to all climatic zones and occupying hundreds of ecological niches, in just tens of thousands of years. Each culture has mental and physical toolkits for survival and reproduction that no individual could possibly learn in a lifetime. Then the advent of agriculture enabled the scale of human society to increase by many orders of magnitude, resulting in megasocieties unlike anything our species had previously experienced. The human cultural adaptive radiation is comparable in scope to the genetic adaptive radiations of major taxonomic groups such as mammals and dinosaurs.22 What else is required to conclude that symbolic thought functions as an inheritance system comparable to the genetic inheritance system?
Despite important differences between the two inheritance systems, most of the core principles that I have described for genetic evolution in previous chapters apply to both, especially with respect to multilevel selection. Regardless of whether a phenotypic trait is genetically inherited, learned, or culturally derived, it can spread by virtue of benefitting individuals compared to other individuals in the same group, by benefitting all individuals in a group compared to other groups, and so on for a multilevel hierarchy of groups. Extending the hierarchy downward, cultural traits can spread at the expense of individuals, similar to cancer cells and meiotic drive genes.23 The basic tradeoffs that create conflicts between levels of selection do not depend upon the mode of inheritance or the distinction between directed vs. undirected variation.
Against this background, human history can be seen as a fossil record of multilevel cultural evolution with major transitions of its own. Thousands of generations of gene-culture coevolution equipped our ancestors with a sophisticated ability to function as corporate units at relatively small social and spatial scales. The genetic architecture of our minds was shaped by this process. Then the invention of agriculture made larger groups possible, but the mechanisms that enable small groups to function as corporate units do not necessarily scale up.24 New culturally derived mechanisms were required that interfaced with older genetic and cultural mechanisms.25 Evolution is inherently a path-dependent historical process, so the culturally derived mechanisms of large-scale functional organization that evolved in some regions of the world need not resemble those that evolved in other regions of the world. For example, the nation-states of Europe are the product of centuries of between-group military and economic competition, which might or might not serve as viable models for Africa or the Middle East.26
Now at last we can proceed from the study of altruism defined in terms of action to the study of altruism defined in terms of thoughts and feelings.