Downloaded from http://jnnp.bmj.com/ on June 9, 2015 - Published by group.bmj.com
Historical note
Engraved hexagons on an Ice Age ivory: a neurological perspective on an anthropological debate INTRODUCTION In the spring of 2013 an exhibition entitled ‘Ice Age art: the arrival of the modern mind’ was mounted at the British Museum in London.1 Numerous objects created from 40 000 years to 20 000 years ago towards the end of the last Ice Age were displayed, and many of them showed intricate carvings including figurative sculptures and engraved drawings, as well as artefacts and ornaments variously decorated with simple or complex patterns and designs. Among these exhibits was a decorated mammoth ivory plaque about 21 000 years old found at Eliseevitchi, midway between today’s Moscow and Kiev. On this 19.1 cm long ivory is a remarkable design: a network of hexagons forming honeycomb lattices which are remarkably well preserved and clearly visible (figure 1). From left to right the lattice pattern is ‘formed by slightly elongated hexagons that become broader lozenges and then revert to hexagons’.1 What inspired the carving of such a specific and complex pattern? Anthropologists have sought to explain how such engravings originated and what they represented, and, intriguingly, a number of authors have invoked neurological explanations. As discussed below, however, while some of their explanations are far from compelling, many are pertinent to speculations on the neurological processes subserving the engraving’s realisation, and on whether the brains of Ice Age humans—anatomically the same as ours—powered artistic creativity similar to our own.
HOW DID THE ENGRAVINGS ORIGINATE? Three possibilities suggest themselves for what led the engraver to create the network of hexagons. First, he (or she) may have observed and ‘copied’ structures or patterns consisting of hexagonal objects he had seen. Second, he may have been inspired by patterns generated intrinsically by the visual system within the eye or, more relevant here, the brain. Third, the decoration may have been entirely original, and created without any obvious ‘template’. Each possibility leads to some conjectures concerning cerebral function in Ice Age people.
Did the engraver copy a hexagonal pattern? First, if the engraver was inspired by observing hexagonal patterns in nature, what structures with this pattern were there to be seen and copied? One anthropological suggestion has been that the ivory’s hexagons resemble the pattern of fish scales, or symbolise a fish.2 This explanation seems unlikely, however, since although fish remains were found in the Eliseevitchi region, as Murray commented: ‘I know of no species of fish with two different kinds of scales on its body’.3 Another suggestion is that the pattern of hexagons represents the bees’ honeycomb. Honeycombs in the wild tend to form nested catenary curves rather than the more rigid structure familiar to beekeepers today, and such wild honeycomb appearances are relevant to form constants discussed below. Turtles and tortoises have carapaces with hexagonal markings too, but, like bees, 1174
these creatures were not present in the harsh cold environment. It is also unlikely that Ice Age people ever saw hexagonal interlocking basalt columns, as occur in the Giant’s Causeway, as this type of volcanic formation is unknown in this region. If, however, the patterns had indeed been observed and copied from nature, it is reasonable to postulate that many thousands of years ago the same or similar regions of the brain known today to be associated with copying would have been enlisted. These regions include the primary motor cortex, prefrontal cortex and posterior parietal cortex,4 with the right parietal lobe being particularly implicated in the processing of spatial relationships, and the left parietal lobe with spatial organisation.5
Do entoptic phenomena account for the hexagons? Second, the visual pattern might have been generated within the engraver’s brain, and then remembered. Such visual, so-called entoptic phenomena include ‘form constants’ or ‘hallucinatory constants’6—the names given by Heinrich Klüver, who noted that hallucinations experienced during the early stages of mescaline intoxication were ‘remarkably uniform as to the appearance of [their] forms and configurations’.6 Among the diverse patterns of these form constants, the honeycomb pattern comprising multiple hexagons is a particularly well recognised example. Klüver also noted the variety of circumstances in which form constants appear, including falling asleep and waking from sleep; gazing at the ceiling; viewing flickering lights or rotating disks; hypoglycaemia; when febrile; in schizophrenia; and during migraine attacks.6 The latter circumstance, together with hallucinations associated with hallucinogenic drugs and trance states, may be particularly pertinent. It is in the visual aura of migraine that the most precise hallucinatory patterns have been illustrated,7 notably those reported and illustrated by Richards detailing his wife’s visual aura.8 However, chiming with Hubel and Wiesel’s findings on the orientation specificity of responses of monkey striate cortical cells,9 while entoptic zigzag patterns are frequently experienced and sometimes depicted, hexagons are not. Thus Podoll and Robinson found very few reports of hexagons and honeycombs ‘seen’ during migraine attacks, although they encountered a number of ‘lattice’ hallucinations in their collection of migraine art.10 Furthermore, in his discussion of the cerebral processes subserving visual aura, Richards had to insert radial lines to join up the zigzags to form hexagons (figure 2).8 Thus, at best, the Eliseevitchi ivory engraving could have been inspired by migrainous visual aura but it is most unlikely to represent a copy. Although entoptic hallucinations including hexagons and honeycomb patterns are well known to occur under the influence of plant-derived hallucinogenic drugs such as mescaline,6 11 it is highly improbable that hallucinogenic plants were available to Europeans at the end of the last Ice Age.12 But entoptic hallucinations have also been associated with shamanism, an aspect which has attracted considerable attention from the anthropological perspective.12–15 The shaman—a ritual specialist who goes into a trance for spiritual, healing or other purposes—is said to progress through stages of the trance associated with increasing alteration of consciousness. Although the evidence has been vigorously challenged,12 Lewis-Williams and colleagues have argued both that shamanism existed in the Ice Age during the Upper Palaeolithic in Europe, and that during the early stages of the trance the shaman typically ‘sees’ those geometrical shapes which recall Klüver’s form constants.14 15 Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
Downloaded from http://jnnp.bmj.com/ on June 9, 2015 - Published by group.bmj.com
Historical note
Figure 1 Mammoth ivory, found at Eliseevitchi. Length 19.1 cm. Reproduced (in colour in the online version) with permission from the Collection of the Peter the Great Museum of Anthropology and Ethnography (Kunstkamera), Russian Academy of Sciences, MAE no. 5298-2850. However, even if experiencing visual hallucinations under the influence of drugs or during a trance, the Ice Age engraver would inevitably be incapable of precision carving, and would either have to rely on a memory of the honeycomb pattern, or relive the pattern, perhaps as a result of visual flashbacks.11 14 In the visual aura of migraine the hallucinations are mainly generated in the visual cortex, but it is less clear which parts of the visual system are responsible for other entoptic phenomena. Surprisingly, form constants such as hexagons are not typically generated by electrical stimulation of the occipital lobes,6 although geometrical and other complex entoptic patterns have been reported when subjects simultaneously received hallucinogenic drugs.16
Did the hexagon pattern emerge as a creative act de novo? If, as implied by the foregoing comments, and in opposition to some anthropologists’ views, there is little compelling evidence that the hexagons on the ivory are attributable either to objects seen in nature or to entoptic phenomena, the third possibility becomes more attractive: the hexagonal pattern emerged de novo as an act of original creativity—‘the mental journey between ideas or concepts that involves either a novel route or novel destination’.17 This requires ‘the ability to hold an image ‘in the mind’s eye’’, together with those ‘neural changes required for this fundamental shift in artistic potential’.18 Perhaps the engraver simply used hexagons, one of only three regular shapes which tessellate without gaps or overlaps, to decoratively ‘tile’ part of the tusk. Whatever the artist’s motives, various theories for the neurobiological basis for all such creativity have been suggested;17 mechanisms subserving creativity and the parts of the brain concerned with imagery and modulating creativity however remain elusive,19 even more so in prehistoric man.
ABSTRACT SYMBOL OR REPRESENTATIONAL ‘ART’? Accepting the likeliest possibility that the honeycomb pattern on the ivory was an example of original creativity, is the pattern an abstract symbol or a figurative representation which might loosely be termed ‘art’, acknowledging that the distinction is arbitrary—witness Gombrich’s expression ‘Ornament as Art’?20 And to add a further twist, regular patterns—perhaps such as those on the Eliseevitchi ivory—may even represent a system of notation, mnemonic aid or recording device, blurring the distinction between an artistic creation and a tool.21 If the hexagons comprise abstract patterns and derive from form constants—whether generated spontaneously, or from migraine, hallucinogenic drugs or mind-altering rituals—they are surely not representational or figurative ‘art’? If, however, the mammoth ivory has been embellished so as to depict a fish with its scales, surely that is such ‘art’? The evidence outlined above favours the conclusion that this network of hexagons was an abstract, symbolic creation, and decorative rather than utilitarian,22 a conclusion which leads to some further neurological observations.
WHAT CEREBRAL PROCESSES SUBSERVED THE CREATION OF THE NETWORK OF HEXAGONS? Figure 2 A honeycomb of hexagons emerges when the thin radial lines are added to the zigzag patterns seen during the visual aura of migraine. Adapted, with permission from Scientific American, from Richards, 19718. Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
The two forms of artistic creativity—abstract and representational—would likely have been subserved by distinct neural processes: using functional MRI, studies of images in respect of their colour, movement and line led Zeki to the ‘general rule… that all abstract works activate more restricted parts of the visual 1175
Downloaded from http://jnnp.bmj.com/ on June 9, 2015 - Published by group.bmj.com
Historical note brain than narrative and representational art’.23 The capacity of the brain more generally to power the artistic creativity which led to the emergence of art during the Ice Age is thought to be associated with an overall increase in brain size, and, more importantly, with the specific growth of the frontal lobes and the increased computational capacity of cortical neurons, perhaps including the potential for massive parallel processing.24 In passing, the perception of beauty, an invaluable facility for the artist and the appreciative viewer, is an attribute of the prefrontal cortex25 which would have participated in the enlargement of the frontal lobes. During primate evolution there was great enlargement too of the temporal-parietal-occipital junction and angular gyrus;22 these structures have been implicated in the convergence of processes subserving proprioception and vision,26 which would have enabled the eye-hand coordination necessary for the intricate carving of complex design.
The motor skills necessary for precision engraving However the hexagonal pattern was conceived, the pattern was realised by an extraordinarily skilled feat of intricate craftsmanship: each side of the numerous hexagons is 2–3 mm long, and was carved using a burin on hard ivory. Such precision demands exquisite motor control, a function that likely implicates the corticospinal tract but more particularly the corticomotor neuronal system, crucial for independent fine finger movements.27 Furthermore, the Ice Age engraver had to employ both hands for the task, one to hold the ivory, the other to manipulate the engraving tool, signifying skilled bimanual interactions. All these visual and motor factors incidentally preclude any possibility of random scratching or doodling28; great skill and dexterity would have been required for a very time-consuming task taking many hours.
To cite Schott GD. J Neurol Neurosurg Psychiatry 2014;85:1174–1176. Received 17 October 2013 Revised 4 December 2013 Accepted 30 December 2013 Published Online First 31 January 2014
▸ http://dx.doi.org/10.1136/jnnp-2014-307569 J Neurol Neurosurg Psychiatry 2014;85:1174–1176. doi:10.1136/jnnp-2013-307044
REFERENCES 1 2 3 4
5 6 7 8 9 10 11
12
THE ICE AGE HONEYCOMB ENGRAVING AFFIRMS ‘THE ARRIVAL OF THE MODERN BRAIN’ Famous wall paintings, such as those in the caves of Chauvet and dated as far back as around 35 000 years ago, as with many of the objects displayed in the British Museum exhibition, leave no doubt that Ice Age people, anatomically the same as us, were consummate representational artists. But an image such as that engraved on the Eliseevitchi ivory demonstrates something more: these people were equally skilled at creating seemingly abstract images. It may not be too speculative, therefore, to suggest that the brain of prehistoric man over 20 000 years ago in terms of its conceptual, creative and artistic abilities was remarkably similar to our own. How apt, therefore, that the exhibition ‘Ice Age art’ was subtitled ‘the arrival of the modern mind’, a subtitle which in the artistic context here could justly be modified to ‘the arrival of the modern brain’.
13
14 15 16
17 18 19 20 21 22
G D Schott Correspondence to Dr G D Schott, The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK; [email protected] Acknowledgements GDS is most grateful to Dr Jill Cook, Deputy Keeper, Department of Prehistory and Europe at the British Museum, for her invaluable help and critical comments. Competing interests None. Provenance and peer review Not commissioned; externally peer reviewed.
23 24 25 26 27 28
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Cook J. Ice Age art: arrival of the modern mind. London: British Museum Press, 2013:134. Marshack A. Upper Paleolithic symbol systems of the Russian Plain: cognitive and comparative analysis. Curr Anthropol 1979;20:271–311. Murray WB. Comment, in: Marshack A. Upper Paleolithic symbol systems of the Russian Plain: cognitive and comparative analysis. Curr Anthropol 1979;20:302. Tzagarakis C, Jerde TA, Lewis SM, et al. Cerebral cortical mechanisms of copying geometrical shapes: a multidimensional scaling analysis of fMRI patterns of activation. Exp Brain Res 2009;194:369–80. McCarthy RA, Warrington EK. Cognitive neuropsychology. A clinical introduction. San Diego: Academic Press, 1990:114. Klüver H. Mescal and mechanisms of hallucinations. Chicago: University of Chicago Press, 1966:22, 64–70. Schott GD. Exploring the visual hallucinations of migraine aura: the tacit contribution of illustration. Brain 2007;130:1690–703. Richards W. The fortification illusions of migraines. Sci Am 1971;224:89–96. Hubel DH, Wiesel TN. Receptive fields and functional architecture of monkey striate cortex. J Physiol 1968;195:215–43. Podoll K, Robinson D. Migraine art. The migraine experience from within. Berkeley: North Atlantic Books, 2008:204–5, 334–7. Siegel RK, Jarvik ME. Drug-induced hallucinations in animals and man. In: Siegel RK, West LJ, eds. Hallucinations. Behavior, experience, and theory. New York: John Wiley and Sons, 1975:81–161. Helventston PA, Bahn PG. Desperately seeking trance plants: testing the ‘Three Stages of Trance’ model. New York: RJJ Communications, 2002. La Barre W. Anthropological perspectives on hallucination and hallucinogens. In: Siegel RK, West LJ, eds. Hallucinations. Behavior, experience, and theory. New York: John Wiley and Sons, 1975:9–52. Lewis-Williams JD, Dowson TA. The signs of all times. Entoptic phenomena in Upper Palaeolithic art. Curr Anthropol 1988;29:201–45. Clottes J, Lewis-Williams D. The shamans of prehistory: trance and magic in the painted caves. New York: Harry N. Abrams, Inc, 1998:14–6. Knoll M, Kugler J, Höfer O, et al. Effects of chemical stimulation of electrically-induced phosphenes on their bandwidth, shape, number and intensity. Confin Neurol 1963;23:201–26. Griffiths TD. Capturing creativity. Brain 2008;131:6–7. Morriss-Kay GM. The evolution of human artistic creativity. J Anat 2010;216:158–76. Zaidel DW. Neuropsychology of art: neurological, cognitive, and evolutionary perspectives. Hove: Psychology Press, 2005:204. Gombrich E. The sense of order: a study in the psychology of decorative art. 2nd edn. London: Phaidon Press, 1984:33. Mithen SJ. The prehistory of the mind: a search for the origins of art, religion and science. London: Phoenix, 1998:195–7. Alpert BO. The creative Ice Age brain: cave art in the light of neuroscience. Santa Fe, NM: Foundation 20 21, 2008:20–1, 98. Zeki S. Inner vision. An exploration of art and the brain. Oxford: Oxford University Press, 1999:207. Solso RL. The psychology of art and the evolution of the conscious brain. Cambridge, Mass; London: MIT Press, 2003:42, 57. Cela-Conde CJ, Marty G, Maestú F, et al. Activation of the prefrontal cortex in the human visual aesthetic perception. Proc Natl Acad Sci USA 2004;101:6321–5. Ramachandran VS. The emerging mind: the Reith Lectures 2003. London: Profile, 2003:867. Lemon RN. Descending pathways in motor control. Annu Rev Neurosci 2008;31:195–218. Henshilwood CS, d’Errico F. Middle Stone Age engravings and their significance to the debate on the emergence of symbolic material culture. In: Henshilwood CS, d’Errico F, eds. Homo Symbolicus: the dawn of language, imagination and spirituality. Amsterdam; Philadelphia: John Benjamin Publishing Co, 2011:90.
Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
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Engraved hexagons on an Ice Age ivory: a neurological perspective on an anthropological debate G D Schott J Neurol Neurosurg Psychiatry 2014 85: 1174-1176 originally published online January 31, 2014
doi: 10.1136/jnnp-2013-307044 Updated information and services can be found at: http://jnnp.bmj.com/content/85/10/1174
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Historical note
Engraved hexagons on an Ice Age ivory: a neurological perspective on an anthropological debate INTRODUCTION In the spring of 2013 an exhibition entitled ‘Ice Age art: the arrival of the modern mind’ was mounted at the British Museum in London.1 Numerous objects created from 40 000 years to 20 000 years ago towards the end of the last Ice Age were displayed, and many of them showed intricate carvings including figurative sculptures and engraved drawings, as well as artefacts and ornaments variously decorated with simple or complex patterns and designs. Among these exhibits was a decorated mammoth ivory plaque about 21 000 years old found at Eliseevitchi, midway between today’s Moscow and Kiev. On this 19.1 cm long ivory is a remarkable design: a network of hexagons forming honeycomb lattices which are remarkably well preserved and clearly visible (figure 1). From left to right the lattice pattern is ‘formed by slightly elongated hexagons that become broader lozenges and then revert to hexagons’.1 What inspired the carving of such a specific and complex pattern? Anthropologists have sought to explain how such engravings originated and what they represented, and, intriguingly, a number of authors have invoked neurological explanations. As discussed below, however, while some of their explanations are far from compelling, many are pertinent to speculations on the neurological processes subserving the engraving’s realisation, and on whether the brains of Ice Age humans—anatomically the same as ours—powered artistic creativity similar to our own.
HOW DID THE ENGRAVINGS ORIGINATE? Three possibilities suggest themselves for what led the engraver to create the network of hexagons. First, he (or she) may have observed and ‘copied’ structures or patterns consisting of hexagonal objects he had seen. Second, he may have been inspired by patterns generated intrinsically by the visual system within the eye or, more relevant here, the brain. Third, the decoration may have been entirely original, and created without any obvious ‘template’. Each possibility leads to some conjectures concerning cerebral function in Ice Age people.
Did the engraver copy a hexagonal pattern? First, if the engraver was inspired by observing hexagonal patterns in nature, what structures with this pattern were there to be seen and copied? One anthropological suggestion has been that the ivory’s hexagons resemble the pattern of fish scales, or symbolise a fish.2 This explanation seems unlikely, however, since although fish remains were found in the Eliseevitchi region, as Murray commented: ‘I know of no species of fish with two different kinds of scales on its body’.3 Another suggestion is that the pattern of hexagons represents the bees’ honeycomb. Honeycombs in the wild tend to form nested catenary curves rather than the more rigid structure familiar to beekeepers today, and such wild honeycomb appearances are relevant to form constants discussed below. Turtles and tortoises have carapaces with hexagonal markings too, but, like bees, 1174
these creatures were not present in the harsh cold environment. It is also unlikely that Ice Age people ever saw hexagonal interlocking basalt columns, as occur in the Giant’s Causeway, as this type of volcanic formation is unknown in this region. If, however, the patterns had indeed been observed and copied from nature, it is reasonable to postulate that many thousands of years ago the same or similar regions of the brain known today to be associated with copying would have been enlisted. These regions include the primary motor cortex, prefrontal cortex and posterior parietal cortex,4 with the right parietal lobe being particularly implicated in the processing of spatial relationships, and the left parietal lobe with spatial organisation.5
Do entoptic phenomena account for the hexagons? Second, the visual pattern might have been generated within the engraver’s brain, and then remembered. Such visual, so-called entoptic phenomena include ‘form constants’ or ‘hallucinatory constants’6—the names given by Heinrich Klüver, who noted that hallucinations experienced during the early stages of mescaline intoxication were ‘remarkably uniform as to the appearance of [their] forms and configurations’.6 Among the diverse patterns of these form constants, the honeycomb pattern comprising multiple hexagons is a particularly well recognised example. Klüver also noted the variety of circumstances in which form constants appear, including falling asleep and waking from sleep; gazing at the ceiling; viewing flickering lights or rotating disks; hypoglycaemia; when febrile; in schizophrenia; and during migraine attacks.6 The latter circumstance, together with hallucinations associated with hallucinogenic drugs and trance states, may be particularly pertinent. It is in the visual aura of migraine that the most precise hallucinatory patterns have been illustrated,7 notably those reported and illustrated by Richards detailing his wife’s visual aura.8 However, chiming with Hubel and Wiesel’s findings on the orientation specificity of responses of monkey striate cortical cells,9 while entoptic zigzag patterns are frequently experienced and sometimes depicted, hexagons are not. Thus Podoll and Robinson found very few reports of hexagons and honeycombs ‘seen’ during migraine attacks, although they encountered a number of ‘lattice’ hallucinations in their collection of migraine art.10 Furthermore, in his discussion of the cerebral processes subserving visual aura, Richards had to insert radial lines to join up the zigzags to form hexagons (figure 2).8 Thus, at best, the Eliseevitchi ivory engraving could have been inspired by migrainous visual aura but it is most unlikely to represent a copy. Although entoptic hallucinations including hexagons and honeycomb patterns are well known to occur under the influence of plant-derived hallucinogenic drugs such as mescaline,6 11 it is highly improbable that hallucinogenic plants were available to Europeans at the end of the last Ice Age.12 But entoptic hallucinations have also been associated with shamanism, an aspect which has attracted considerable attention from the anthropological perspective.12–15 The shaman—a ritual specialist who goes into a trance for spiritual, healing or other purposes—is said to progress through stages of the trance associated with increasing alteration of consciousness. Although the evidence has been vigorously challenged,12 Lewis-Williams and colleagues have argued both that shamanism existed in the Ice Age during the Upper Palaeolithic in Europe, and that during the early stages of the trance the shaman typically ‘sees’ those geometrical shapes which recall Klüver’s form constants.14 15 Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
Downloaded from http://jnnp.bmj.com/ on June 9, 2015 - Published by group.bmj.com
Historical note
Figure 1 Mammoth ivory, found at Eliseevitchi. Length 19.1 cm. Reproduced (in colour in the online version) with permission from the Collection of the Peter the Great Museum of Anthropology and Ethnography (Kunstkamera), Russian Academy of Sciences, MAE no. 5298-2850. However, even if experiencing visual hallucinations under the influence of drugs or during a trance, the Ice Age engraver would inevitably be incapable of precision carving, and would either have to rely on a memory of the honeycomb pattern, or relive the pattern, perhaps as a result of visual flashbacks.11 14 In the visual aura of migraine the hallucinations are mainly generated in the visual cortex, but it is less clear which parts of the visual system are responsible for other entoptic phenomena. Surprisingly, form constants such as hexagons are not typically generated by electrical stimulation of the occipital lobes,6 although geometrical and other complex entoptic patterns have been reported when subjects simultaneously received hallucinogenic drugs.16
Did the hexagon pattern emerge as a creative act de novo? If, as implied by the foregoing comments, and in opposition to some anthropologists’ views, there is little compelling evidence that the hexagons on the ivory are attributable either to objects seen in nature or to entoptic phenomena, the third possibility becomes more attractive: the hexagonal pattern emerged de novo as an act of original creativity—‘the mental journey between ideas or concepts that involves either a novel route or novel destination’.17 This requires ‘the ability to hold an image ‘in the mind’s eye’’, together with those ‘neural changes required for this fundamental shift in artistic potential’.18 Perhaps the engraver simply used hexagons, one of only three regular shapes which tessellate without gaps or overlaps, to decoratively ‘tile’ part of the tusk. Whatever the artist’s motives, various theories for the neurobiological basis for all such creativity have been suggested;17 mechanisms subserving creativity and the parts of the brain concerned with imagery and modulating creativity however remain elusive,19 even more so in prehistoric man.
ABSTRACT SYMBOL OR REPRESENTATIONAL ‘ART’? Accepting the likeliest possibility that the honeycomb pattern on the ivory was an example of original creativity, is the pattern an abstract symbol or a figurative representation which might loosely be termed ‘art’, acknowledging that the distinction is arbitrary—witness Gombrich’s expression ‘Ornament as Art’?20 And to add a further twist, regular patterns—perhaps such as those on the Eliseevitchi ivory—may even represent a system of notation, mnemonic aid or recording device, blurring the distinction between an artistic creation and a tool.21 If the hexagons comprise abstract patterns and derive from form constants—whether generated spontaneously, or from migraine, hallucinogenic drugs or mind-altering rituals—they are surely not representational or figurative ‘art’? If, however, the mammoth ivory has been embellished so as to depict a fish with its scales, surely that is such ‘art’? The evidence outlined above favours the conclusion that this network of hexagons was an abstract, symbolic creation, and decorative rather than utilitarian,22 a conclusion which leads to some further neurological observations.
WHAT CEREBRAL PROCESSES SUBSERVED THE CREATION OF THE NETWORK OF HEXAGONS? Figure 2 A honeycomb of hexagons emerges when the thin radial lines are added to the zigzag patterns seen during the visual aura of migraine. Adapted, with permission from Scientific American, from Richards, 19718. Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
The two forms of artistic creativity—abstract and representational—would likely have been subserved by distinct neural processes: using functional MRI, studies of images in respect of their colour, movement and line led Zeki to the ‘general rule… that all abstract works activate more restricted parts of the visual 1175
Downloaded from http://jnnp.bmj.com/ on June 9, 2015 - Published by group.bmj.com
Historical note brain than narrative and representational art’.23 The capacity of the brain more generally to power the artistic creativity which led to the emergence of art during the Ice Age is thought to be associated with an overall increase in brain size, and, more importantly, with the specific growth of the frontal lobes and the increased computational capacity of cortical neurons, perhaps including the potential for massive parallel processing.24 In passing, the perception of beauty, an invaluable facility for the artist and the appreciative viewer, is an attribute of the prefrontal cortex25 which would have participated in the enlargement of the frontal lobes. During primate evolution there was great enlargement too of the temporal-parietal-occipital junction and angular gyrus;22 these structures have been implicated in the convergence of processes subserving proprioception and vision,26 which would have enabled the eye-hand coordination necessary for the intricate carving of complex design.
The motor skills necessary for precision engraving However the hexagonal pattern was conceived, the pattern was realised by an extraordinarily skilled feat of intricate craftsmanship: each side of the numerous hexagons is 2–3 mm long, and was carved using a burin on hard ivory. Such precision demands exquisite motor control, a function that likely implicates the corticospinal tract but more particularly the corticomotor neuronal system, crucial for independent fine finger movements.27 Furthermore, the Ice Age engraver had to employ both hands for the task, one to hold the ivory, the other to manipulate the engraving tool, signifying skilled bimanual interactions. All these visual and motor factors incidentally preclude any possibility of random scratching or doodling28; great skill and dexterity would have been required for a very time-consuming task taking many hours.
To cite Schott GD. J Neurol Neurosurg Psychiatry 2014;85:1174–1176. Received 17 October 2013 Revised 4 December 2013 Accepted 30 December 2013 Published Online First 31 January 2014
▸ http://dx.doi.org/10.1136/jnnp-2014-307569 J Neurol Neurosurg Psychiatry 2014;85:1174–1176. doi:10.1136/jnnp-2013-307044
REFERENCES 1 2 3 4
5 6 7 8 9 10 11
12
THE ICE AGE HONEYCOMB ENGRAVING AFFIRMS ‘THE ARRIVAL OF THE MODERN BRAIN’ Famous wall paintings, such as those in the caves of Chauvet and dated as far back as around 35 000 years ago, as with many of the objects displayed in the British Museum exhibition, leave no doubt that Ice Age people, anatomically the same as us, were consummate representational artists. But an image such as that engraved on the Eliseevitchi ivory demonstrates something more: these people were equally skilled at creating seemingly abstract images. It may not be too speculative, therefore, to suggest that the brain of prehistoric man over 20 000 years ago in terms of its conceptual, creative and artistic abilities was remarkably similar to our own. How apt, therefore, that the exhibition ‘Ice Age art’ was subtitled ‘the arrival of the modern mind’, a subtitle which in the artistic context here could justly be modified to ‘the arrival of the modern brain’.
13
14 15 16
17 18 19 20 21 22
G D Schott Correspondence to Dr G D Schott, The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK; [email protected] Acknowledgements GDS is most grateful to Dr Jill Cook, Deputy Keeper, Department of Prehistory and Europe at the British Museum, for her invaluable help and critical comments. Competing interests None. Provenance and peer review Not commissioned; externally peer reviewed.
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Schott GD. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10
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Engraved hexagons on an Ice Age ivory: a neurological perspective on an anthropological debate G D Schott J Neurol Neurosurg Psychiatry 2014 85: 1174-1176 originally published online January 31, 2014
doi: 10.1136/jnnp-2013-307044 Updated information and services can be found at: http://jnnp.bmj.com/content/85/10/1174
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