A History of the Brain

From Stone Age surgery to modern neuroscience

Andrew P. Wickens

• Publisher: Psychology Press
• Year: 2014
• Print ISBN: 9781848723658
• eBook ISBN: 9781317744825
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

A History of the Brain tells the full story of neuroscience, from antiquity to the present day. It describes how we have come to understand the biological nature of the brain, beginning in prehistoric times, and progressing to the twentieth century with the development of Modern Neuroscience.

This is the first time a history of the brain has been written in a narrative way, emphasizing how our understanding of the brain and nervous system has developed over time, with the development of the disciplines of anatomy, pharmacology, physiology, psychology and neurosurgery. The book covers:

• beliefs about the brain in ancient Egypt, Greece and Rome
• the Medieval period, Renaissance and Enlightenment
• the nineteenth century
• the most important advances in the twentieth century and future directions in neuroscience.

The discoveries leading to the development of modern neuroscience gave rise to one of the most exciting and fascinating stories in the whole of science. Written for readers with no prior knowledge of the brain or history, the book will delight students, and will also be of great interest to researchers and lecturers with an interest in understanding how we have arrived at our present knowledge of the brain.

1

HEAD OR HEART? THE ANCIENT SEARCH FOR THE SOUL

It ought to be generally known that the source of our pleasure, merriment, laughter and amusement, as of our grief, pain, anxiety, and tears, is none other than the brain.

Hippocrates

And of course, the brain is not responsible for any of the sensations at all. The correct view is that the seat and source of sensation is the region of the heart.

Aristotle

Summary

Much of this chapter covers a period from about 3000 BC when the first seeds of Western civilisation were sown in Mesopotamia and Egypt, to the great flowering of ancient Greece with the rise of Athens as its cultural centre during the fifth century BC. It is by far the longest period of history covered in this book, stretching over two millennia. Curiously for much of it, people attributed different causes to their behaviour than we do today. They saw their thoughts, desires and actions arising not from the brain, but the heart. This belief is clearly seen in ancient Egypt where bodies were preserved for the after-life. The process of mummification tells us a great deal about how the Egyptians regarded the soul for they scrupulously preserved the heart as the repository of its earthly deeds, and saw its ‘goodness’ as the key to eternity. In contrast, the brain was extracted through the nose with an iron hook and thrown away! Nor were they alone in their disregard for the brain. The primacy of the heart was maintained throughout Biblical times. Indeed, it is a revealing fact that the ‘brain’ is never mentioned in the Bible as a cause of behaviour, whereas it is replete with references to the heart. Even when we come to the ancient Greeks who replaced myth and superstition with logic and reason, the heart is still attributed with mental powers. This is shown, for example, in their earliest stories, namely those of Homer, whose characters are frequently depicted as puppets of fate, propelled into action by divine will and emotional impulses originating from the heart. Although Homer was aware of the brain’s existence, he never attributed it as a cause of action. In fact, we have to wait until the fifth century BC, before the earliest reference to the brain as the site of reasoning is found in the fragmented writings of the Ionian philosopher Alcmaeon. However, this view is more strongly endorsed in the great collection of works by Hippocrates (also in the fifth century) who leaves the reader with no doubt that the brain provides the individual with all his mental faculties and intelligence. Yet, this belief was not universally accepted. Although supported by the great philosopher Plato, the importance of the brain was dismissed by his pupil Aristotle who continued to attribute the heart with sensory and mental powers. This may appear perplexing to a modern reader, although it must be remembered that the ancient Greeks up to Aristotle had not yet discovered the nervous system. Consequently, they were forced to attribute the body’s principal site of communication to the heart, and its great multitude of blood vessels. This system was also seen as containing the psyche, a spiritual entity, which provided the animating and life-giving forces of the person.

The emergence of the human mind

It is often said that nothing in biology makes sense unless understood in evolutionary terms, and this must also surely be true of the human brain. Arguably, the human brain is evolution’s greatest achievement – a journey that can be said to have begun on Earth some three to four billion years ago when the first simple forms of life such as single cells first appeared. In this great time span, however, the human brain is a relatively recent event. In fact, modern humans are basically the latest in a long line of two-legged apes, known as hominins, which diverged from a chimpanzee-like ancestor some seven million years ago. Many types of this creature would exist, although the first to have begun the hominoid lineage to human beings is believed to be Australopithecus afarensis (a famous example is “Lucy”), which appeared over three million years ago. These animals were about 1.3 metres tall (four feet) with relatively small brains of about 450 cubic centimetres (cc) not dissimilar to a chimpanzee. However, their upright posture and bipedalism allowed them to free their hands and walk long distances, a characteristic leading them to have a very different lifestyle. Although Australopithecus afarensis remained unchanged for one million years, they evolved into the larger brained human-like Homo habilis (literally ‘handy man’) some 2.3 million years ago in eastern Africa.¹ In turn, this ape was the ancestor of several other hominin species including one appearing in the fossil record some 500,000 years later called Homo erectus, with a more robust and taller skeleton accompanied by prominent brow ridges above its eyes. However, perhaps the most striking characteristic of this ape was the size of its brain, which almost doubles Homo habilis at about 1100 cc. Thus, in just over two million years, beginning with Australopithecus, the hominin brain had almost trebled in size.

Around 600,000 years ago the fossil record begins to show the emergence of a new ape in Africa lacking the prominent brow of habilis. Instead they had a higher vaulted cranium containing a brain similar in size to our own at around 1400 cc. Although little evidence survives about the rest of their skeleton, these creatures are generally recognised as archaic Homo sapiens (meaning ‘wise man’). And, as far as we can tell, they developed into modern day human beings (or Homo sapiens sapiens) about 200,000 years ago. Originating in places such as Ethiopia, Sudan, Tanzania and South Africa, these creatures had a slight and nimble skeletal frame, with opposable thumbs that could manipulate objects dexterously. While they are the only surviving branch of the hominin family, for much of their early evolutionary history they were not alone. Around 150,000 years ago and surviving to about 30,000 years ago, we also see evidence of the Neanderthals.² Robust, heavily muscled, and short in stature, these creatures were common in Europe during the Last Ice Age. While Neanderthals are a side branch of the hominoid evolutionary tree with extinction as their fate, they remain of great interest, not least because their brains were bigger than our own with a volume of around 1550 cc. Why they became extinct is not clear. It is most likely they were not able to compete for resources as effectively as Homo sapiens, although recent genetic evidence suggests some degree of inter-breeding with humans may also have occurred.

The earliest Homo sapiens were skilled in their use of stone technology and produced a diverse range of tools including sharpened blades, small portable axes, and spears. This helped them be skilful nomadic hunter gatherers who roamed and explored their environment in small groups to search for game and food – a pursuit also encouraging them to leave their African homeland in various migrations, including one 60,000 years ago when they crossed the Arabian Peninsula to reach Asia and Australia. While more intelligent than their ancestors some anthropologists have pointed out that these first humans, nonetheless, do not show any appreciably different behaviour from their ancestors. Nor do they put their technology to any radically new use. But some 40,000 years ago in the Late Stone Age this situation changed abruptly in a cultural shift, which some have dubbed ‘the mind’s big bang’. The earliest evidence of this change is found in Europe with the behaviour of so-called Cro-Magnon man who inhabited the caves of France and northern Spain.³ Suddenly, these early humans are seen to be constructing shelters and simple dwellings, which they lit and warmed by fire, allowing them to cook and create permanent settlements. We also see Cro-Magnon man making tools from bone, ivory and antler, and wearing clothes from furs adorned with beads and buttons. He adds to his fashion spectacle by wearing carved amulets, pendants and bracelets. Cro-Magnon was also the first human to create art as shown by magnificent cave paintings that include depictions of horses, mammoths, reindeer and other mammals. His artistic talents even extended to music as shown by flute-like instruments made from bone. The reasons for this change in human behaviour are highly contentious in anthropological circles with some arguing it represents a sudden major advance in human thinking,⁴ perhaps driven on by social pressures, or the development of language encouraging new thought processes, while others see it as something that only appeared gradually. Whatever the cause, it is nonetheless clear at this point in our ancestry, we are witnessing the start of something very special: a being who is much like us today.

However, there is another remarkable change associated with Late Stone Age man: they buried their dead, and often left a wide range of personal belongings in their graves including necklaces, bracelets, hunting weapons and animal bones. Early humans also often went to considerable trouble to position the body and arrange stones in a careful manner around the grave. Although Neanderthals are known to have buried their dead in shallow pits some 100,000 years ago, and may have occasionally left bodies with simple remnants, their mortuary or ritualistic behaviours were not as sophisticated as the early humans whose burials often involved red ochre (a form of iron oxide that yields a pigment when heated), which was used to paint the animal bones placed in graves. This practice shows that our own ancestors associated this pigment with death, making the important mental leap of using it as part of a symbolic burial ritual. The burial of the dead is a highly revealing change in behaviour for it shows one of our earliest beliefs, perhaps beginning some 27,000 to 23,000 years ago, was in a spiritual existence beyond our earthly senses where souls depart following the death of the individual. In other words, man is beginning to question the world and become self-aware of his own existence. It is arguably the first evidence that consciousness is emerging from the human brain.

The contemplation of life after death is a crucial turning point in our human journey as it surely entails some type of spiritual belief – encouraging an awareness of mortal existence and a puzzling of one’s place in the greater scheme of things leading to religious practice. Early man must also have noticed that the dead stopped breathing and realised breath (later to become the psyche or pneuma in the writings of the ancient Greeks) was vital to life. This would have inevitably encouraged a belief in two different worlds: one associated with physical reality where the living exist, and another that was non-material and spiritual. Extending this belief to its natural conclusion, it is a small step to regard living things as fundamentally different from non-living things since they contain some non-physical element, or spiritual force, providing them with life and animation.⁵ The adoption of such beliefs was to have several far reaching consequences. One was a belief in animism in which natural phenomena such as animals, plants, rocks, thunder etc were imbued with a wilful or life-like presence. Another was the idea that body and spirit exist as separate entities. This was to become a central tenet of all the world’s great religions, and provided the idea that there is a difference between the spiritual mind and physical body. Despite its great antiquity, this is still a concept strongly influencing the way we think of ourselves today. Indeed, there are some, including ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Acknowledgements
• 1 Head or heart? The ancient search for the soul
• 2 The discovery of the nervous system
• 3 From late antiquity to the Renaissance: the Cell Doctrine
• 4 Searching for the ghost in the machine
• 5 A new life force: animal electricity
• 6 The rise and fall of phrenology
• 7 The nerve cell laid bare
• 8 The return of the reflex
• 9 Mapping the cerebral cortex
• 10 The rise of psychiatry and neurology
• 11 Solving the mystery of the nerve impulse
• 12 The discovery of chemical neurotransmission
• 13 Neurosurgery and clinical tales
• 14 Surveying the last 50 years and looking ahead
• Author Index
• Subject Index