The Evolution of Human Cleverness

Richard Hallam

• Publisher: Routledge
• Year: 2022
• ISBN:
  9781000584318
• Edition: 1
• Topic: Psychologie
• Subtopic: Kognitive Psychologie & Kognition

The Evolution of Human Cleverness presents a unique introduction to the way human cognitive abilities have evolved. The book comprises a series of mini-essays on distinct topics in which technical terms are simplified, considering how humans made the long journey from our ape-like ancestors to become capable of higher-level reasoning and problem solving.

All the topics are cross-linked, allowing the reader to dip in and out, but certain key concepts run through the underlying reasoning. Chiefly, these are adaptation and selection, the distinction between ultimate and proximate causes of behaviour, gene–culture co-evolution, and domain-general versus domain-specific cognitive processes. The book should help the reader draw lessons for the human species as a whole, especially in view of the environmental threats to its own existence.

Entries have been carefully crafted to cut through scientific jargon, providing bite-sized and digestible chunks of knowledge, making the topic accessible for students and lay readers alike. The author draws on research from diverse fields including Psychology, Anthropology, Archaeology, Biology, and Neuroscience to provide an unbiased account of the field, making it an ideal text for students of all levels.

Part 1 Introduction

1 Aims

DOI: 10.4324/9781003165507-2

The evolution of hominin cleverness covers a vast area of knowledge in numerous academic disciplines. The task I have set myself for this book is to summarise a mosaic of somewhat disconnected islands of expertise that deal with different aspects of the subject. The concept of cleverness ties them together, and this concept is broader than intelligence. I have aimed to provide bite-sized chunks of knowledge in which technical terms are simplified. I do not focus too much on the historical origins of competing schools of thought. It is not possible to cover everything that is relevant. The work of integration is left largely up to the reader who can dip at will into any entry and follow the links to associated material. Despite the mosaic structure, the entries do link up and they all cast light on the subject.

It is a challenge to get to grips with this material, but the subject is of interest to almost everyone. Speculation about the way our earliest ancestors thought and behaved deals with a past so remote that agreement can hardly be expected. Scientists who prefer to deal with ‘the facts’ tend to study fossils and archaeological traces. One 850-page encyclopaedia of human evolution devotes only around 200 words to ‘cognition’, and there are no entries for consciousness or intelligence [591]. In a survey of expert opinion on evolutionary origins, all seven ‘unique human traits’ selected for the survey were of an anatomical nature [551].

My background is that of a behavioural psychologist and psychotherapist, not a biologist, and this is bound to influence the way I present some topics. I have given little consideration to neuroscience, and with regard to the cleverness of animals, I consider only humans’ nearest primate relatives, the two species of chimpanzee. I have tried to compensate for scant coverage by liberally referencing books and articles, each of which is numbered in the text, and listed at the end of the book. Each entry is fairly short, usually between 500 and 2,500 words, hopefully sufficient to whet the appetite but not too heavy on stomach or brain.

All entries have a bearing on the evolution of hominin cleverness. It is generally accepted that humans evolved from an animal that resembles the living great apes. The main thread tying the topics together is the evolutionary thinking first presented clearly by Charles Darwin. I will assume that our earliest ancestors evolved to become cleverer in order to deal with any problem thrown at them, and that this in some way furthered their survival and reproductive success. Of course, living humans do not always produce ‘clever’ solutions to problems, and the problems they pose are not always well chosen. For perhaps the first time in the evolution of the species, humans have become aware of the possibility of their own extinction, brought about by numerous unthinking actions. Human cleverness did not evolve to solve this kind of problem. In the vast expanse of hominin evolution, our ancestors lived in relatively small groups and their cleverness seemed to be adapted to community living. Consequently, contemporary humans, living in huge populations, with access to technology and forms of communication that are still only decades old, are liable to all kinds of stupidity.

Cleverness nevertheless differentiates Homo sapiens most clearly from other primates, given that our emotions and sexual appetites are not that dissimilar. In terms of survival and reproduction, the human species has been outstandingly successful, but the verdict must be out for a longer timescale. Evolution is not driven by foresight, although humans are now technically in the position, through gene editing and selective breeding, to contemplate different paths for their own future. It is already ‘saving’ other species from extinction in order to save itself. There is a sense that humans are becoming aware that they have to apply their problem-solving skills for the collective interest of the species. It is questionable whether humans actually have a capacity to imagine and deal with problems on a larger scale. Our ancestors evolved in the way that they did because they learned to solve small-scale problems together. Unlike our closest relatives, who seem to be primarily self-oriented, hominins began to solve problems for mutual benefit.

If our hominin ancestors resembled competitive apes, it seems remarkable that they evolved into a cooperative species with pro-social motives. In some way, they recognised that shared cleverness would benefit everyone. In the contemporary world, these ancestral traits reassert themselves most strongly when disaster threatens. This return to mutual support is not a product of philosophical reflection or a resurgent sense of morality. The impulse must be as hardwired as sex because, at some stage of our evolution, it proved unbeatable.

Evolution works without a purpose on the material available, and so in this sense, human cooperation is an ‘accident’. It seems to have been an accident of both nature and culture. Hominins were clever enough, once a capacity to formulate a problem symbolically had evolved, to appreciate its nature and seek a solution. Non-human primates face choices, moment to moment, between eating, mating, grooming, sleeping, playing, defending a territory, etc., but when hominins evolved the capacity to recall past experiences and imagine future possibilities, a whole new world of problems loomed into view. Rules evolved to regulate what would otherwise be an anarchic state of affairs. The resulting ‘cultures’ were probably Heath Robinson affairs from which the wheels could easily spin off. Contemporary cultures are also extremely variable and undergo constant change, often in ways that social scientists are unable to predict. Nevertheless, the ancestral condition of communal problem-solving has probably been retained as a feature of ‘human nature’.

For day-to-day problems, humans turn to family, friends, counsellors, and voluntary organisations. This form of problem-solving is in marked contrast to the rule-governed procedures of policymakers, planners, and scientists. Society-wide problems are rarely addressed by communal decision-making as it might have been conducted by our hunting and gathering forebears. ‘Social policy’ for the common good is presently the domain of politicians, specialists, and technologists. These experts do of course provide solutions to threats to survival: medicine, non-polluting forms of energy, industrial farming, welfare benefits, etc. Experts are largely motivated by career progression, a badge of honour, or commercial success. The links with communal problem-solving are tenuous.

The belief that science and technology are capable of producing a solution to almost any problem is strong. Scientists see themselves as working towards a unified body of knowledge, towards ‘consilience’, the title of a book by the biologist E. O. Wilson [588]. The aim is to get closer to objective truth, which, it is assumed, will assist the human race to understand and solve the predicaments it confronts. It is as if the destiny of human evolution is cleverness itself. Scientists are sometimes happy to take on the mantle of a priesthood, sharing the myth that the solution to any new challenge is just a matter of extra effort and diligence. They stand for ‘progress’, even though each application of science tends to bring additional problems in its wake. An alternative destiny, more consistent with our earlier evolution, would be to get by as best we can, designing stable and serviceable social arrangements. With this aim in mind, an ambition to travel to Mars, let alone live there, would be a superfluous luxury.

Perhaps, our human ancestors always thought that the grass was greener on the other side of the hill and that this was a stimulus for the evolution of their problem-solving powers. Eventually, humans found themselves endowed with an unfettered imagination going beyond anything available to their mere senses. Problem-solving for its own sake became sufficiently interesting to fill up the whole day. This book explores how we might have arrived with a capacity for abstract thinking and its intelligent application. Humans are both blessed and burdened with an enquiring nature. In the face of what seem to be enormous problems of our own making, directing our attention onto the evolution of human cleverness might assist us in meeting them. Cleverness is the only resource we have, apart from a desire to do better.

Simplification of technical terms

Certain technical terms that are shared across disciplines are retained. The term hominin refers to humans and their forebears, plus any other bipedal primate that split off from an ancestral lineage around 6–9 million years ago (mya). Apart from an erect posture, hominins have a larger brain than other primates and they behave in more complex ways. Hominins were formerly called hominids, but the primate family Hominidae is a classification that now includes primates known as the great apes.

I have tried to limit the number of technical terms and also devise simplifications of my own. For practitioners of the ‘palaeosciences’, the correct technical terms trip off the tongue but with respect to geological eras and phases in evolution, it is easier to refer to ‘numbers of years ago’, that is, thousand years ago (kya), or million years ago (mya). Human history is very recent, but the bigger picture is the Miocene (23.03–5.3 mya), Pliocene (5.3–2.6 mya), Pleistocene (2.6 mya–11.7 kya), and Holocene (the current epoch since the end of the last major ice age). Climate variability has been an extremely significant influence on human evolution, possibly accounting for the fact that agricultural revolutions occurred independently in different parts of the world approximately 12 kya [566:41]. This marks the end of the last major ice age.

There is a bewildering number of Latin names for hominin genera and species. Where appropriate, I mention them in detail. Otherwise, I refer to Ancestral hominins, our early ape-like ancestors living approximately between 7 mya and 2 mya, such as Australopithecus. Early Homo (2.5 mya to around 1 mya), refers to different species of Homo, the most notable of which is H. erectus. Late Homo, from around 800 kya, includes H. heidelbergensis from which H. neanderthalensis and H. sapiens are assumed to have evolved.

The hominin past has also been classified into eras of stone tool production. Oldowan tools were made with one or a few flakes that were chipped off with another stone (2.6–1.7 mya). Acheulean tools were oval and pear-shaped ‘hand-axes’ made from various rocks, requiring much more skill to produce (from around 1.8 mya). Later tools, with various refinements for different purposes, belong to what is called the Mousterian period (160–40 kya). The Middle Stone Age refers to African prehistory (280–25 kya). The New Stone Age (Neolithic) began around 12 kya and ended with the arrival of civilisations approximately 3.5 kya.

Speculation about hominin evolution has greatly benefitted through comparisons with other great apes, principally, the common chimpanzee (Pan troglodytes) and the bonobo (Pan paniscus). Humans were not descended from a species of great ape but from an ancestor common to all of them. It is widely assumed that the two species just mentioned resembled the common ancestor. Their separation into distinct species is thought to have occurred around 1.5–2 mya. I will refer to both as ‘chimpanzees’, distinguishing them only where necessary. Humans are primates, but I will occasionally use the word primate to refer only to its non-human representatives.

2 Overview

DOI: 10.4324/9781003165507-3

The title of this book refers to cleverness rather than intelligence, two words that carry an important difference in meaning. The English language is rich with words, many of them slang, that slide between these concepts. For ‘intelligence’ we have brainy/brainless, bright/dull, gifted/dense. For cleverness, we have profound/shallow, thoughtful/ill-considered, level-headed/muddle-headed. The intelligence quotient or IQ is derived from answers to questions and puzzles that have little to do with cleverness because they do not refer to any real-world problem. They sample the size of a person’s vocabulary but not any practical use of it. In another typical item, the subject is required to rearrange coloured blocks to match a pattern. While intelligence is highly valued, people give equal weight to being wise, balanced, or shrewd. Practical problem-solving is a matter of getting what you want, given the constraints and resources. Intelligence and cleverness are closely related but nevertheless somewhat different traits (see 75. The evolution of reasoning).

For our human ancestors, the key requirement was to survive and reproduce. Cleverness was needed for techniques of foraging and for working together on everything from child-care to managing relationships within their own community. Unfortunately, they left few clues of their cleverness in the latter respect. Even the fossils of their skeletons and their stone tools do not give a lot away. Perhaps, our early ancestors gazed at the night sky, seeing it as a giant crossword puzzle, but the next morning they would have had to find food and water, look out for predators, and keep an eye on infants liable to wander off.

The concept of cleverness in the sense of finding adaptive solutions to problems of survival can be applied to all species and obviously takes a variety of forms. For humans, intelligence in the somewhat narrow sense of reasoning about abstract relationships is probably the most convincing explanation for recent human success and world dominance. The need to combine it with cleverness has, however, never gone away. This book surveys its early foundations, the first 7 million years rather than the last 10,000.

Virtually every aspect of hominin evolution has a bearing on cleverness, and there is no neat story to be told. Each species is clever in its own way, whether they are crows, dolphins, or octopuses. Unrelated species can hit upon similarly clever ways of solving a problem, a phenomenon called convergent evolution. For instance, bats and birds have evolved to fly although the mechanism has been arrived at by different routes. The cleverness of our closest primate relatives is most relevant to humans, partly because our earliest ancestors resembled them and faced similar problems. It is still not known what led hominins into becoming extra-clever primates. A few captive apes have been taught a form of sign language and some have been happy to be raised alongside human children (see 44. Signing chimpanzees, 45. Home-reared chimpanzees). We can identify closely with them, but the evolutionary path of their social behaviour and life history are distinctly different (see 20. Family structure, pair bonding, and communal breeding).

Many academic disciplines have devoted themselves to the puzzle of hominin clever ness. With the exception of comparative and evolutionary psychology, the science of psychology has not been especially concerned with evolutionary questions [208]. The currently popular paradigm, cognitive science, theorises about humans who already display sophisticated abilities in the area of memory, reasoning, and decision-making. This book aims to link up very different disciplines, and so it is necessary to examine the conceptual, methodological, and philosophical positions that differentiate them. These have to be addressed in order to connect the findings of one discipline with those of another.

Some of the entries give a brief summary of essential concepts while others are an in-depth discussion of aspects of cleverness. Evolutionary psychology is distinctive in the sense of wholeheartedly endorsing neo-Darwinian principles. It traces present-day psychological traits to their likely origins during the longest sustained period of a H. sapiens lifestyle, namely hunting and gathering during the past 300,000 years. It is only in the last 50–100,000 years that humans have exerted such an influence on their environment that the main pressures that shaped their evolution were ones th...