In his brilliant and beautiful poem ‘The Death of Allegory’, Billy Collins wonders what became of all those personifications of metaphysical concepts found in medieval woodcuts and eighteenth-century statuary:
Truth cantering on a powerful horse,
Chastity, eyes downcast, fluttering with veils …
Reason with her crown and Constancy alert behind a helm’.
Once upon a time, these allegorical figures spent their days travelling between the Valley of Humiliation and the Sunlit Uplands of Joy. But where are they now? In the poem, Billy Collins imagines that they have retired to ‘a Florida for tropes’.
But neuroscience has since brought allegorical figures out of retirement, and relocated them to different postal districts of the brain, where Truth, Wisdom, Villainy, Schadenfreude and Envy have each been given plots of land – although Envy’s isn’t as well situated as the others. (Much to Schadenfreude’s delight. A delight that Villainy took no time in telling Envy about, you can be sure. Truth was going to mention it as well, but Wisdom advised against it.)
It took state-of-the-art high-tech fMRI machines to bring back the medieval idea of anthropomorphising abstract concepts. But there is one crucial difference between allegorist and brain-mapper. Neither Hieronymus Bosch nor John Bunyan believed you could actually meet a concept in the flesh. They never confused parable with history, nor revelation for the view from a window. They never believed that the Valley of Humiliation or Garden of Earthly Delights were actual places in the physical world. They imagined them as being lots of places and none. While writing Pilgrim’s Progress, Bunyan did not believe that there is a flesh and blood Mr Despondency who has a daughter called Much-Afraid. But unlike Bosch and Bunyan, the brain-mappers really do believe in the flesh-and-blood existence of abstract concepts, albeit microscopic flesh and blood.
And here’s a curious thing. For some reason, they think that oxytocin is the trail scent of abstract concepts. The brain scanners’ hounds follow the scent of oxytocin, tracking the Big Foot of Guilt down to its lair in The Cave of Shame, which lies in the folds of the temporal sulcus, or under the shadowy overhang of the posterior angulate gyrus. The overpowering scent of oxytocin has led to a rash of peer-reviewed papers with titles that sound like they might have come from the casebook of Elizabethan alchemists such as Simon Forman or John Dee:
‘Oxytocin increases trust in humans’*
* M. Kosfeld, M. Heinrichs et al., Nature, 2005.
‘Intranasal administration of oxytocin increases envy and schadenfreude (gloating)’*
* S. G. Shamay-Tsoory et al, Biological Psychiatry, 2009.
‘Oxytocin improves “mind-reading” in humans’*
* G. Domes et al., Biological Psychiatry, 2007.
But change is in the air. Peer-reviewed papers increasingly address the bad odour to which these berserk extrapolations have subjected neuroscience. In the decade or so since the first of these oxytocin papers was published there has been a move away from reductivism. A good example of this is Meghan Puglia et al.’s paper ‘Epigenetic modification of the oxytocin receptor gene influences the perception of anger and fear in the human brain’.* This paper argues that the role of the oxytocin molecule needs to be understood as part of a dynamic, complex interplay between brain, body and outside world:
* Meghan Puglia et al., PNAS, 2015.
Phylogenetically, it is improbable that a biochemical with such wide-ranging targets evolved to have a highly focused effect on specialized processes, like trust or envy. Rather, oxytocin likely has a more general effect on basic biological systems that ultimately support these complex social-cognitive constructs.
It is with a sigh of relief that you move away from the Simon Forman/John Dee quackery in which a single shot of magic potion (oxytocin) produces jealousy or envy or bitterness, and into something which at least approaches a recognisably human scale of complexity, namely that oxytocin forms only part of a wider array of developmental systems interacting with each other. This is not to say that complexity is always closer to the truth than simplicity, or that we should respect fiddly theories rather than pithy ones. It’s just to say that when it comes to explaining human states of mind a multiplicity of weakly acting causal pathways sounds about right.
Epigenetics has rescued neuroscience from searching for answers in the neuron or the gene alone. The study of non-DNA heredity, epigenetics has entailed a move away from simple linear explanations to ones that involve the integration of multiple causes – a move, that is, from mythology to science.
The enriched conditions of a pregnant rat’s immediate habitat, for example, accelerate the in utero maturation of her pup’s visual cortex, as if daughter cells were being told the outside world is worth looking at. As a result of this epigenetic cascade her pup will be born with precocious eyesight.
The cytoplasm of the rat’s brain cells influence how the chromosome modifies gene expression. Within each cell’s nucleus chromosomes control gene expression by way of transcription factors such as the enzyme methyltransferase, which mutes now this, now that strip of DNA. Once a gene has been methylated its expression is silenced. By the same token, sections of DNA that have lain dormant for generations can be activated by these protein methyl markers.
Cellular cytoplasm, in turn, depends on ecological conditions in the womb, while womb ecology depends, in its turn, on environment, nutrition, social conditions, experience. You may noticed the strange absence of the womb from accounts of evolutionary biology. Unlike genes that code for behaviour, it is not scientifically respectable to talk about the womb, even though genes that code one-to-one for behaviour do not actually exist, whereas wombs do. Wombs, we are told, are about development not evolution. But Eva Jablonka and Marion Lamb persuasively argue that once the zygote has been formed in the womb, the evolutionary story is only just beginning.* What the mother passes through her placenta to the amniotic sac, for example, has been shown to influence her offspring’s offspring’s offspring. The same is true of her milk. Disease resistance and immune response are major factors in evolution, and a mother’s milk passes on a cocktail of immune-boosters, which will influence which of her offspring survive to fertility. And among this cocktail of course is our old friend oxytocin, which brings us back to epigenetic factors on brain development.
* Eva Jablonka & Marion J. Lamb, Evolution in Four Dimensions, 2014.
Epigenetics teaches us to be sceptical about seeing oxytocin as magic bullet, to be chary of drug companies trying to sell the NHS on plans to use intranasal oxytocin as way of treating behavioural and affective disorders. The weakness of this techno-fix is that it neglects the patient’s history. If past conditions have led transcription factors to suppress the oxytocin receptor gene OXTR, then a snort of oxytocin will be useless. Whether or not oxytocin can help us depends on the OXTR gene, and the functioning of OXTR depends on our past. Epigenetics has reintroduced history to the neuroscience, which is what is signally absent from those papers that hunt for allegorical figures such as Wisdom, Trust, Truth, Virtue and Courage down among the basal ganglia or up on the rocky promontory of the left frontal lobe.
Even though wisdom, anger and fear can never be sufficiently explained by neurobiology, Meghan Puglia and her team show it is possible to conduct useful and scientifically sound experiments into the neurobiology of psychology and emotion. Just as allegory gave way to history in art and literature so we can hope that allegory may give way to history in neuroscience.