The Emergence of Religion in Human Evolution

Margaret Boone Rappaport, Christopher J. Corbally

• Publisher: Routledge
• Year: 2019
• Print ISBN:
  9780367245207
• eBook ISBN:
  9781000760552
• Topic: Theology & Religion
• Subtopic: Christian Theology

Religious capacity is a highly elaborate, neurocognitive human trait that has a solid evolutionary foundation. This book uses a multidisciplinary approach to describe millions of years of biological innovations that eventually give rise to the modern trait and its varied expression in humanity's many religions. The authors present a scientific model and a central thesis that the brain organs, networks, and capacities that allowed humans to survive physically also gave our species the ability to create theologies, find sustenance in religious practice, and use religion to support the social group. Yet, the trait of religious capacity remains non-obligatory, like reading and mathematics. The individual can choose not to use it.

The approach relies on research findings in nine disciplines, including the work of countless neuroscientists, paleoneurologists, archaeologists, cognitive scientists, and psychologists.

This is a cutting-edge examination of the evolutionary origins of humanity's interaction with the supernatural. It will be of keen interest to academics working in Religious Studies, Neuroscience, Cognitive Science, Anthropology, Evolutionary Biology, and Psychology.

Part I
Introduction to theory

1 New sciences, new findings, and a new model

Two sweeping images of our past

Readers are invited to take a fascinating 65-million-year journey from the end of the Mesozoic Era when dinosaurs roamed the Earth, and the beginning of the Cenozoic Era, often called the Age of Mammals, to today (Table 1.1). A biological order of animals named the “Primates” emerged from relatives of today’s tree shrews, and they were active, social, and smart (Table 1.2). The highest primate, so far, entertains beliefs in gods, reasons morally, adjudicates his peers, and conveys culture to offspring in a learning process spanning over two decades. Moral and religious thinking, and some types of decision-making, appear to mature only in a person’s 20s and 30s, and sometimes never. Those few children who are precocious catch our attention.

Table 1.1 Geological and Biological Time Periods

Table 1.2 Classification of the Order Primates, Commonly Known Forms

In a true sense, the human experiences of self, of God, and of the cosmos are stunning achievements of organic evolution. The neurocognitive capacities that nurture the imaginations of scientists and artists, and that fill the hearts and minds of modern humans with stories, lessons, and admonishments have evolutionary roots that run deep, before our species, Homo sapiens, ever emerged. At the beginning of our investigation into what makes us human, we discerned two images of the distant past that guided our research into depths we had never explored before. It was only later that we realized these two images would lead to the present analysis of the evolutionary foundations of religious thinking in our modern species and subspecies, Homo sapiens sapiens.

Ancient ape ancestry

The first image of the past spans three continents—Europe, Asia, and Africa—and three geological epochs. During the Miocene Epoch from approximately 23 to 5.3 million years ago, the then-highest primates called “apes” spread geographically and diversified genetically into 14 different genera. The Miocene was known for its “radiation” of apes, which have important features distinguishing them from monkeys, who evolved earlier in the Oligocene (Table 1.1). The Miocene ape radiation produced a large, varied population, in terms of both census numbers and effective population size, a measure of population quality. It was this population from which later human and anthropoid ape species diverged (Casanovas-Vilar et al. 2011), and it is in them that we search for early foundations of religious capacity.

Around 23 million years ago, the fossil record produces a transitional species, Proconsul, who had both monkey and ape features. By the middle of the Miocene Epoch, 19 million years ago, Proconsul qualified as a true ape—bigger, stronger, and smarter. It is that date we use in the following pages for the appearance of the great apes. It is important to ask: Did these early apes have religious thinking? No, but they had some important foundations for it: Sociality and intelligence, including the ability to improvise. Only three Orders of Mammalia evolved with an important feature involving the reorganization of the lateral cerebellum, which, in Primates, eventually enabled the type of intelligence needed to engage in religious thinking and theological creativity.

Both Old World monkeys and great apes first appeared in Africa, but by the middle of the Miocene, a land bridge to Eurasia opened up because sea levels dropped, and apes colonized Eurasia, along with many other fauna. Most ancient apes became extinct, but one led to later species of African great apes and humans. David Begun diagrams this Last Common Ancestor (LCA) at about 12 million years ago, although who that LCA was, exactly, is still not clear (2016, 3). The latest thinking is that apes evolved from the line giving rise to the modern gibbon, now called “a lesser ape,” around 15 million years ago. Ancient gorillas evolved first, and then chimpanzees, bonobos, and humans evolved later. The question of which of the Miocene apes gave rise to the human line remains outstanding. It is a focus of active research. When the LCA is clarified, it will be “big news,” so readers should watch for it in the future.

In the Pliocene Epoch, lasting from 5.3 to 2.5 million years ago, partially bipedal ape-like proto-humans evolved, including the well-known australopithecines (“Lucy”). Another type of diversification occurred in the Pliocene, across Africa and Eurasia, from Olduvai Gorge in Tanzania to Ledi-Geraru in Ethiopia, and from present-day Turkey, Georgia, and Israel, all the way to China and Indonesia. One of the early, Miocene-Pliocene bipedal hominins that has been considered a possible ancestor of the human line is Ardipithecus ramidus, found in Ethiopia, dating from 5.6 to 4.4 million years ago (Boisserie 2010). In the past ten years, the status of Ardipithecus has been a subject of substantial debate, although the fossils suggest that bipedalism was habitual. The fossil reconstructions certainly look more proto-human than anything that resembles a chimpanzee. However, the proportions of the limbs remain ape-like, with very long arms. We will see that change with the first clear example of our genus Homo, in Homo habilis, who had longer legs and shorter arms, in the human pattern.

Not all of the bipedal apes were our ancestors, but perhaps one was—or perhaps one that has not yet been found. The exact transitional forms from the Miocene apes to the human line are the stuff of future research findings, now ongoing at a rapid pace. Homo sapiens and Homo erectus, who came before us, remain the only species that enjoyed full and efficient bipedalism and used the trait to hunt, helping to feed even larger brains. It is only logical that evolution produced a series of species transitioning to a new form of locomotion. Walking and running changed everything.

The living great apes are called “relics,” because the great apes continue to decline in numbers and range. They remain relatively large, partially terrestrial, intensely social, and they have no tail. The latter absence requires that apes have good flexibility and stabilization to replace what a tail once did. The flexibility inherent to all apes is part of our human inheritance, allowing us to move easily with flexible joints and strong limbs—in climbing a tree, swimming in a pool, and maneuvering around the International Space Station. The brains of apes were already growing in size well before the human line diverged, six to seven million years ago. Apes grow and mature slowly with strong mother-infant bonds, and their brains are large compared to other mammals. Humans inherit all these features, and many others.

As two scientists, we were fascinated by the large, genetically diverse group of Miocene apes (Begun 2003, 2016). They are the source of humans’ basic biological model, as well as many of our strengths, and a genetic diversity that was largely lost in successively smaller groups of early hominins, until we emerged far more genetically uniform than they were. Without jumping too far forward, we note here that the flexibility of apes is also used in a great deal of religious behavior among believers, but especially by religious leaders who also make use of the great apes’ tendency for periodic demonstrativeness. In voodoo ritual and in the Sunday morning Mass, we see the physicality imparted to humans by their ape ancestry.

Knowledge has been accumulating from primatologists about this large, genetically varied population of Miocene apes, because, of course, they gave rise to humans, and, as we are now discovering, a range of apes that were partially bipedal. The search goes on and new reports suggest that the dental root and pulp canal morphology of a species named Graecopithecus, one of the partially bipedal proto-humans from Greece and Bulgaria, point to a genetic affinity with hominins—and with us. Fuss and colleagues confirm that the “split of our clade (Hominini, human forms) from the Panini (chimpanzee forms) is undocumented in the fossil record” (Fuss et al. 2017). Therefore, there is work to be done to clarify the relationships among the great apes and humans, identify the LCA, when and where the split likely occurred, and trace that split in the genomes of apes and humans, if we can.

However, it is important to ask: Do living humans and apes have common origins? Indeed, they do. Knowledge of minute similarities and differences in morphology, not to mention genes, proves our common origins with the great apes. In many ways, apes are responsible for the framework, the boundaries, of so many unusual adaptations on the human line, not least of which is the neurocognitive trait of religious thinking. Apes were and remain big, smart, social, sensitive, and demonstrative at times. So are we humans.

Murky statistics

The second image of the past that guided our investigation was equally intriguing and productive. Its nature stems from the long timeframe of generation after generation of genetically evolving hominins. This picture of evolution is ancient, large in scope, and branching in configuration. The genomes of successive species are represented in each reproductive individual by microscopic helices of base pairs forming DNA. These are the “genes” we refer to in the pages that follow, knowing full well that the term has some flexibility in meaning because, for example, some genes are regulatory and some specify how proteins are formed. Some are large and some are physically small. Some operate uniquely and others operate along with other genes. There are many different kinds of genes.

Lines of genes carried in the genome of living humans go back to early members of our genus Homo. What makes this image extremely vivid is work in genetics that identifies specific genes reaching back hundreds of thousands, even millions of years ago, long before our species, Homo sapiens, emerged. The history of our genetic evolution is written in our own genome. This understanding changes the meaning of “the human species,” because some genes in the modern human species emerged before the species stabilized 150,000 years ago, perhaps as late as 120,000 years ago, depending on analysis of the human globular skull form and other advanced features. Many of us carry very old genes, documenting a history of the lines of apes and early hominins who came before us. Our species is relatively young, but some of our most important genes are very, very old, for example, genes that manage energy metabolism. Harris and Hey (1999) document a gene guiding energy metabolism that emerged 400,000–200,000 years ago.

Improved energy metabolism was enormously important in the evolution of human cognition (including religious thinking) because enlarging brains required so much energy. It is important to remember that by the time we see the small bipedal ape Homo habilis in the fossil record, the brain was already relatively large and presenting this (now-)earliest member of our genus with the problem of obtaining enough energy to supply its requirements. Given that Homo habilis was making a transition in niche from the ape pattern of foraging and sleeping in trees, to the more human pattern of aggressive scavenging of meat during the day (Coolidge and Wynn 2009, 207), it is not surprising that energy metabolism was changing. Homo habilis needed meat to feed its already-enlarging brain, an energy-hungry organ. The human brain still uses a disproportionate amount of energy in comparison to other organs.

Another example of a very old gene comes from Blum and Jakobsson (2011) who have found very old, living genes that date 1.5–1 million years ago, long before Homo sapiens evolved. This was a time when Homo erectus made tools, hunted, and eventually, around a million years ago, left Africa to colonize the rest of the Old World, before modern humans even existed. Genes have been discovered in modern humans that go back two million years ago, when Homo habilis was still alive. This species of the genus Homo remains the earliest known fossil in our genus. The species made our first tools, although earlier tools were likely made by the australopithecines, three to four million years ago (e.g., McPherron et al. 2010).

It was the lines to those “deep divergences” that we pictured, giving us a glimpse of how very old some aspects of our biology and behavior are. This research on very ancient gene copies is not the only research showing deep divergences in human gene trees. Work with our genetic past combines knowledge of the human genome, the genomes of our near relatives like the Neanderthals, and the genomes of living apes, which have now all been sequenced and are being investigated in laboratories worldwide. Differences with these species point to what makes humans unique.

Combining knowledge of ancient genomes with the theory of population genetics, which is based on probability, allows scientists to estimate the size and genetic variability of ancient populations. This work looks deeply into the lines of genes we now use, in order to see where they first appeared. Eugene Harris (2015) provides a good explanation of the difference between “gene trees” and “species trees,” and why they are not the same. A gene can be shared through time among species old and new. On the other hand, a species is defined by a certain number and variety of genes, though time, in a discrete and stable pattern. Harris clarifies the reasons for the “murkiness” of this image of genomes going back so far, in branching patterns of groups splitting from other larger groups, and the imprecision of our knowledge. Population genetics uses probability to estimate gene frequencies in ancient populations, so it necessarily has a certain imprecision. Using the combined theory of genomics and population genetics, scientists have been able to sort out that it is indeed more likely that humans are more closely related to living chimpanzees than living gorillas. Good to settle that one!

In summary, these two deeply seated images, one of Miocene apes and Pliocene proto-human bipeds, and the other image of genes with deep divergences, piqued our curiosity. We wondered whether, in all that information, there were clues about the origins of religious thinking. Indeed, there were hints in the scientific findings, and the need for a new model for testing. After all, the earliest anthropologists formed grand outlines of the stages of “religious evolution” (for example, Edward Burnett Tylor, described in Strenski 2006). Indeed, anthropologists have arrayed elaborate, detailed schemes in scholarly works up to the present day (Bellah 2011). None of these triangulates data from genomics, neuroscience, and cognitive science, with archaeology and paleoneurology. When we looked at findings from those disciplines, what we found was scattered evidence of a logical progression of cognitive capacities that was consistent with the demography, ecology, and cultures of earlier forms of humans.

Toward a multi-disciplinary approach to the evolution of human religion

Religious capacity and religious thinking

Rarely, if ever, has this extraordinary story of primate evolution been mapped onto the emergence of one of the most complex of human biological traits, religious capacity, or more specifically, the neurocognitive capacity...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Dedication Page
• Table of Contents
• List of tables
• Preface
• Part I Introduction to theory
• Part II The model
• Part III The implications
• Index