This post accompanies a talk that given by me in Somerville College chapel on 27th January, 2013. Unlike many of the posts that I have put up so far, which have been related to my teaching, this is connected to my own research. Over the next few months the blog will have a lot more to say about my research.
God and the Origins of Neuroscience
In 1664 one of the first thorough physiological descriptions of the brain and nerves was published, with the title Cerebri Anatome, cui accessit Nervorum Descriptio et Usus (‘The Anatomy of the Brain, to which is added the Description and Use of the Nerves’). The book’s author was Thomas Willis (1621-1675), a prominent medical doctor and – by this time – the Sedleian Professor of Natural Philosophy at Oxford University. Willis opened the book with a remarkable dedication to the then Archbishop of Canterbury, Gilbert Sheldon (the man who financed the building of the Sheldonian Theatre):
For when I had resolved to unlock the secret places of Mans Mind, and to look into the living and breathing Chapel of the Deity (as far as our weakness was able) I thought it not lawful to make use of the Favours and Patronage of a less Person, neither perhaps would it have become me. For You indeed are He, who most happily presides (both by Merit and Authority) over all our Temples and Sacred Things. Therefore after I had slain so many Victims, whole Hecatombs almost of all Animals, in the Anatomical Court, I could not have thought them rightly offered, unless they had been brought to the most holy Altar of Your Grace.
It is fascinating to see here how Willis suggests that the human brain – the object of his inquiries – was nothing less than ‘the living and breathing Chapel of the Deity’. In fact, this entire passage is full of religious imagery; the last sentence paints a picture of Willis dedicating the many creatures that he dissected as sacrifices at the altar of the Temple of Solomon, depicting Sheldon as the High Priest. The story that I will tell here about Willis’s Anatomy of the Brain is now, however, one about the interconnections between ‘science’ and ‘religion’ in the past. Instead, it is about people for whom making such associations seemed entirely natural, and for whom dissecting the brain was to search for (what they saw as) the elusive, semi-divine immortal soul.
Thomas Willis and his Work
Thomas Willis, who ran an extremely successful medical practice, belonged to a philosophical circle based initially in Oxford that grew into Britain’s modern day academy of science, the Royal Society. Among his friends and colleagues were the chemist Robert Boyle, John Wilkins (who attempted to devise a universal language) and Christopher Wren, architect of the Sheldonian Theatre. By the 1660s Willis had decided to investigate the workings of the human brain and nervous system. With the assistance of several others, including Wren, he set about the large number of dissections of human and animal bodies that would be needed to complete the work.
Willis seems to have felt keenly the disturbing and unpleasant aspects of his work. On one occasion in 1650 Willis had been about to begin a dissection when he discovered that the body, freshly arrived from the gallows, was a still-living person who had somehow survived her execution. Yet he also felt that dissection was the only way to get the knowledge that he sought:
Minerva was born from the Brain, Vulcan with his Instruments playing the Midwife: For either by this way, viz. by Wounds and Death, by Anatomy, and a Caesarean Birth, Truth will be brought to Light, or for ever lye hid.
Discoveries and Theories
By June 1663, according to a letter written by Willis’s assistant Richard Lower, the work was nearly at an end and Wren had nearly finished the book’s beautiful illustrations. In 1664, the book was published.
Ask any neurologist today why Willis’s work is important, and he or she will tell you that the Anatomy is the founding work of modern neurology (a term coined by Willis himself). In the Cerebri Anatome he announced two discoveries – made as the result of exhaustive anatomies – that hold true today. The first was a circle of arteries that supply blood to the base of the brain, the so-called ‘Circle of Willis‘. Second, and even more important, was his successful demonstration that different parts of the brain, identifiable as separate structures, regulate distinct bodily and mental functions. The cerebellum and medulla oblongata, for example, appeared to regulate involuntary and motor functions. Higher cognitive functions, including the operations of imagination (which for Willis meant, roughly speaking, having ideas of things and placing them alongside each other) and memory, belonged to the cerebrum, the brain proper.
Willis arrived at such interesting conclusions because he pursued a comparative method. Rather than just investigate human brains, he dissected many different animal brains, including birds, cats and sheep, in order to compare them all together. This revealed that human and animal brains are similar in many respects, and that some animal brains are more similar to human brains than others.
Let’s take the example of cats. Willis observed that the cerebellum of cats is very similar to the human cerebellum, differing only in its size. Yet the cerebrum in cats differs very much from the human cerebrum. The human cerebrum is full of folds, giving the ‘grey matter’ its characteristic convoluted appearance. But the cat’s cerebrum has many fewer of these folds, arranged in a much simpler fashion. For Willis, these differences – a very similar cerebellum and a much simpler (and proportionately smaller) cerebrum – accounted in some measure for the differences in behaviour between cats and humans:
Those Gyrations or Turnings about in four footed beasts are fewer, and in some, as in a Cat, they are found to be in a certain figure and order: wherefore this Brute thinks on, or remembers scarce anything but that the instincts and needs of Nature suggest. In the lesser four-footed beasts, also in Fowls and Fishes, the superficies of the brain being plain and even, wants all cranklings and turnings about: wherefore these sort of Animals comprehend or learn by imitation fewer things, and those almost only of one kind; for that in such, distinct cells, and parted one from another, are wanting, in which the divers Species and Ideas of things are kept apart.
To put it in simpler terms, Willis argued that humans and animals have similar involuntary and motor functions, and this could be accounted for by the presence of a near-identical structure in the brain. But the human capacity for imagination – for combining ideas – and memory could partially be accounted for by the more complex structure of the cerebrum.
The Search for the Soul
But what about the creatures that in fact have very similar brains to humans? Willis knew that some animals had brains with much better-developed cerebra. I am not sure if Willis had primates in mind when he started to discuss this issue, but it is worth mentioning that by the end of the seventeenth century it was quite well known that primate brains were very similar to those of humans. In 1698 Edward Tyson brought out Orang-Outang, sive Homo Sylvestris: or, the Anatomy of a Pygmie Compared with that of a Monkey, an Ape, and a Man, a work that explicitly noted this fact. Compare his images of the Chimpanzee brain with that of a human from Willis’s Cerebri Anatome:
Willis did not deduce from this, as you might expect, a sort of evolutionary theory about human origins. Instead, he used the similarity between human and animal brains to form conclusions about the thing that, in a way, he had been searching for all along – the immortal soul, referred to by him as the ‘rational soul’. The problem was like this. True, humans and animals had very similar brains. But humans also seem to be capable of a great deal more conscious thought and deliberate action than animals. Willis and others had noticed that animals such as primates (and even dolphins) seem to exhibit emotional states. Nevertheless, Willis saw that the differences between human and animal cognition are very great indeed. Since there was no structural difference in the brain (that he could observe), he attributed the differences to the presence, in the human brain, of an immortal soul – a unique gift from God that distinguished humans from animals. Therefore, animals (Willis used the word ‘brutes’) had a machine-like soul, the functions of which could be attributed to the machinery of the brain. Willis stated the matter in a later work, De Anima Brutorum (1672) (‘On the Soul of Brutes’), like this:
As we have shewn, by comparing the Corporeal [bodily] Soul of the Brute, with the Rational Soul of Man, what vast difference there is between them, perhaps it might be to this purpose, to compare the Brains of either, and to observe their differences. But this Anatomy being elsewhere made, we have noted little or no difference in the Head of either, as to the Figures and Exterior Coformations of the Parts, the Bulk only excepted; that from hence we concluded, the Soul Common to Man with Brutes, to be only Corporeal [part of the body], and immediately to use these Organs
The search for the soul, and by extension an attempt to work out the place of humans in relation to God, was an important part of Willis’s anatomical agenda. He lived in a time and a place when neurological research had striking, immediate implications for how people conceived of the experience of having feelings, ideas, knowing things and believing (or not) in God. Willis was not alone in contemplating such things, and in trying to find out precisely where the soul might find its home in the brain. Willis concluded that the soul must inhabit a body called the corpus callosum (see the diagram above), a structure that links the cerebrum with the cerebellum and medulla oblongata. The great French philosopher René Descartes, meanwhile, had settled for the pineal gland, which sits nearby.
The Cerebri Anatome proved immensely influential as soon as it came out, and contemporaries lost no time at all in working out its implications for matters of religious belief, mental health and the appreciation of the arts and literature. Although Willis decided to attribute many of the mind’s functions to the immortal soul, his argument that even some of our thoughts and feelings are caused by the mechanics of the brain was controversial, and powerful. It provided people with new ways of thinking about the causes of pleasure and pain, as well as mental disturbance, in turn leading them to develop theories about art and mental illness that have powerful legacies today. I will explore some of these in future posts.