Archaeo-optics, or archaeological optics, is the study of the experience and ritual use of light by ancient peoples. Archaeological optics is a branch of sensory archaeology, which explores human perceptions of the physical environment in the remote past, and is a sibling of archaeoastronomy, which deals with ancient observations of celestial bodies, and archaeological acoustics, which deals with applications of sound.
Research by several investigators around the world has uncovered how ancient peoples encountered and used the camera obscura principle for a variety of purposes. In a darkened chamber, light passing through a small opening can create haunting and ephemeral moving images, which could have triggered and reinforced ground breaking modes of thought, forms of representation, and belief in otherworldly realms.Gatton, M. (2009). "First Light: Inside the Palaeolithic camera obscura." In Acts of Seeing: Artists, Scientists and the History of the Visual -- a volume dedicated to Martin Kemp (Assimina Kaniari and Marina Wallace, eds.) London: Zidane. 153.
Optical basis
Light Visible light, a small portion of the electromagnetic spectrum, encompasses wavelengths between 380-750 nanometers, which humans perceive as the colors of the spectrum: red, orange, yellow, green, blue, indigo, and violet. Light behaves according to a well-defined set of rules: it travels in straight lines, unless otherwise refracted or reflected by another object, or curved by gravity.
Vision An eye is essentially a darkened chamber with a small hole in front that allows light to enter. The lens, just behind the pupil's aperture, is perfectly clear but appears black because the interior space behind it is dark. Rays of light pass through the lens, producing an upside-down image on the retina.Explanation of camera obscura operations derived from Pollack, P. (1969). The Picture History of Photography: From the Earliest Beginnings to the Present Day. New York: Harry N. Abrams. 18. The brain reorients the image. This optical process of projecting an inverted image is known as a camera obscura (from the Latin, meaning dark room). The first pinhole/camera obscura eyes evolved about 540 million years ago on a sea mollusk, known as a nautilus, during the Cambrian period. The camera obscura principle is primordial, and life on earth has evolved to take advantage of it.
Camera obscura The camera obscura principle is not limited to eyes, or even lenses, but works with a small hole, or aperture, and any darkened space of whatever size or shape. In modern times, camera obscuras have been fashioned from shoeboxes, oatmeal boxes, soda cans, cookie containers, seashells, eggshells, refrigerators, tents, trucks, airplane hangars, and even hollowed out forms of snow and dirt. A camera obscura can also be produced by a small hole in a roof, wall, or window-shutter through which the view of the outside is projected onto a wall inside a darkened room.Gernsheim, H. and Gernsheim, A. (1969). The History of Photography: From the Camera Obscura to the Beginning of the Modern Era. New York: McGraw-Hill. 17. Biologist Donald Perry went on an expedition into the rain forest of Costa Rica where he climbed into the cavity of a large hollow tree, and discovered a small hole that projected an upside-down image of the outside world onto the opposite interior wall of the trunk.Perry, D. (1988). Life above the Jungle Floor. New York: Simon and Schuster. 46-47. This sort of experience is available across time.Renner, E. (2004). Pinhole Photography: Rediscovering a Historic Technique (3rd ed). Oxford: Focal Press. 3.
The image created appears like an upside-down movie. A camera obscura relies on the contrast between the bright exterior world and a dim interior space, so that a greater contrast produces a more obvious projected image. Absolute darkness in the interior is not necessary, but there must be a significant difference between the two illumination levels.
Archaeological basis
Architecture The archaeological record is replete with excavations of built structures across time, but due to the natural decay of materials and the vagaries of preservation, the further backward in time, the less likely it is for artifacts to have survived. For example, Paleolithic shelter constructions from the Lower Paleolithic (c. 2,600,000–300,000 BP) and Middle Paleolithic (c. 300,000–45,000 BP) are generally less complete and thus subject to interpretation, while those dating to the Upper Paleolithic (c. 45,000–10,000 BP) are both more numerous and better preserved. Paleolithic structures generally have no remaining superstructure, and must be inferred from a footprint of artifacts.For a good overview of Palaeolithic dwellings structures and strategies see Cattelain, P. and Hauzeur, A. (1998). "Des premiers abris aux premières maisons." In Les grandes inventions de la Préhistoire (Bellier C. and Cattelain, P. eds.) (Guides archéologiques du Malgré-Tout) Treignes: CEDARC. 37–46; and De Beaune, S. (2012). "Aux origins de la construction." In Édifice et Artifice (R. Carvais, A. Guillerme, V. Nègre, J. Sakarovitch, eds.) Premier Congrès francophone d’histoire de la construction Paris, 2008 Paris: Piccard. 77–89.
By contrast, some Neolithic structures retain above ground elements. The Neolithic saw the rise of agriculture and the establishment of settlements, which produced a surplus of foodstuffs and an increase in population density. A large, coordinated labor force enabled the process of hauling enormous stones to build large, permanent structures. By about 5,000 BP, many groups of people over a widespread area were erecting large timbers and stones, or megaliths, to enclose communal spaces. Into historical times, the development of writing offered another layer of information, with descriptions of the physical appearance, materials, design, use, and events related to structures. This combination of remnants and records enhances the accuracy of archaeo-optical analysis.
Archaeological optics and archaeoastronomy There is some evidence that prehistorical structures oriented upon the sun's position on the horizon also created camera obscura situations. Examples in Western Europe include midwinter sunrise at Newgrange,O’Kelly, M. (1982). Newgrange. Archaeology, Art and Legend. London, Thames and Hudson. 117, 123–5. midwinter sunset at Maeshowe,MacKie, E.W. (1997). "Maeshowe and the Winter Solstice: ceremonial aspects of the Orkney Grooved Ware culture." Antiquity 71. 338-59. and midsummer sunrise at Bryn Celli Ddu.Burrow, S. (2010). "Bryn Celli Ddu Passage Tomb, Anglesey: Alignment, Construction, Date and Ritual." In Proceedings of the Prehistoric Society 76. 261.
While archaeoastronomical studies have traditionally discussed these kinds of monument as observatories, fieldwork conducted in the 1990s at Balnuaran of Clava by Ronnie Scott and Tim Phillips suggests the midwinter sunset would have cast images inside two passage tombs. By temporarily reconstructing the collapsed roofs of these monuments, they noted that the act of viewing the sun along their passageways was not only potentially blinding but could only be clearly viewed by one person at a time. In contrast, an audience of over twenty people could stand with their backs to the opening to observe the effects of sunlight falling upon deliberately patterned stonework built into walls of both chambers.Scott, R. and Phillips, T. (1999). "Clava: Light at the End of the Tunnel." Current Archaeology 165. 332-5. These observations inspired Scott to speculate that these structures were camera obscuras, and that an optical projection of the sun's disc would reproduce the movements of the sun through the sky for many people to see at once.Scott, R. and Phillips, T. (1998). "Archaeological experiment at Balnuaran of Clava North Eastern cairn on 20th and 22nd December 1997." In Sites and Monuments Archive: <http://her.highland.gov.uk/hbsmrgatewayhighland/DataFiles/LibraryLinkFiles/37677.pdf>
Archaeological optics and the archaeology of the senses Archaeological optics contributes to a wider discipline, the archaeology of the senses. Rather than just recording the remains of the past such as standing stones or built walls, this wider discipline emphasizes how the spaces in-between these features could have been arenas for sensory experiences, even if parts of the original structures have disappeared. Among the senses, vision has been a major consideration, including studies of visibility between sites,Woodward, A.B. and Woodwood, P.J. (1996). "The topography of some barrow cemeteries in Bronze Age Wessex." In Proceedings of the Prehistoric Society 62. 275-91. interactions with geology and topography,Bradley, R. (1998). Ruined buildings, ruined stones: enclosures, tombs and natural places in the Neolithic of south-west England. World Archaeology 30. 13-22. archaeoastronomical alignment,Ruggles, C. (1999). Astronomy in Prehistoric Britain and Ireland. London: Yale University Press. or color symbolism.Jones, A. and MacGregor, G., eds. (2002). Colouring the past: the significance of colour in archaeological research. London: Berg. At the same time, anthropology has revealed societies that emphasize the other sensesHowes, D. and Classen, C., eds. (1991). The varieties of sensory experience. London: Berg. including qualities such as scent and smell.Classen, C., Howes, D., and Synnott, A. (1994). Aroma: the cultural history of smell. London: Routledge. The social significance of the sensory of food and drink,Hamilakis, Y. (1999). "Food technologies/technologies of the body: the social context of wine and oil production and consumption in Bronze Age Crete." In World Archaeology 31(1). 38-54. and touch and textureCummings, V. (2002). "Experiencing texture and transformation in the British Neolithic."In Oxford Journal of Archaeology 21(3). 249-61. can also be considered.
Other studies have examined archaeomusicology and archaeoacoustics.Scarre, C and Lawson, G., eds. (2006). Archaeoacoustics. Cambridge: McDonald Institute for Archaeological Research. Palaeolithic bone artifacts have been interpreted as musical instruments,Megaw, J.V.S. (1960). "Penny whistles and prehistory." Antiquity 34, 6-13. or ‘sound producing devices’,Lund. C. (1981). "The archaeomusicology of Scandinavia." In World Archaeology 12. 246-65. while some natural features within caves have been found to emit unusual sounds.Dams, L. (1984). "Preliminary findings at the ‘Organ’ Sanctuary in the cave of Nerja, Malaga, Spain." In Oxford Journal of Archaeology 3. 1-14. There have also been suggestions that Paleolithic cave art clusters in locations where caverns have especially resonant properties.Reznikoff, I. and Dauvois, M. (1988). "La dimension sonore des grottes ornées." In Bulletin de la Société Préhistorique Française 85. 238-46. In the 1990s the sonic properties of built architecture came under increasing scrutiny with investigations into vocally induced resonances inside chambered Neolithic sites,Devereux, P. and Jahn, R (1996). "Preliminary investigations and cognitive considerations of the acoustical resonances of selected archaeological sites." In Antiquity 70. 665-6. as well as the wider acoustic phenomenon within a variety of megalithic structures.Watson, A. and Keating. D. (1999). "Architecture and sound: an acoustic analysis of megalithic monuments in prehistoric Britain." In Antiquity 73. 325-36.
An archaeology of the senses, including archaeological optics, emphasizes that the past was inhabited by living people whose experiences were inherently partial and subjective. Indeed, this subjectivity might have lent both meaning and mystery to events occurring within ancient structures. This acknowledges that the senses were likely to have been used and understood in very different ways by people through time.
Development of the field of archaeological optics