Archaeo-optics

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.

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.

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. 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.

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. 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. This sort of experience is available across time.

...
Wikipedia