There is a plain in the Peruvian desert, between the Inca and Nazca valleys, about 200 miles south of Lima. An assortment of perfectly straight lines, some miles long, mark this plain. Some lines run parallel and others intersect to form a grand geometric form.
Trapezoidal zones, strange symbols and pictures of birds and other animals (e.g. killer whale, spider, monkey etc) are seen in and around the lines, but everything is drawn on such a large scale it can be appreciated only from the sky.
Most readers will have come across the Nazca Lines at some time. Phenomena such as this are of perennial interest to TV documentary-makers.
It is fascinating to ponder on the meaning of these lines and shapes drawn so large on the Peruvian desert. Explanations have ranged from astronomical maps to landing strips for alien spacecraft.
However, it seems most likely to me that the lines are an expression of the religious rituals of the people who lived there 2,000 years ago.
The forms were not discovered until the early 1930s when they were spotted by aircraft surveying the region for water. The question immediately arose as to the significance of these giant markings and drawings. The most favoured explanations offered have to do, one way or another, with the sky.
Maria Reiche, a German-born mathematics tutor from Lima, has devoted the last 50 years to studying, protecting and recording the desert markings. She has shown how the marks were made. The desert is paved with fist-size rocks washed down from the Andes in ancient floodings. Where the rocks are exposed to the sun, bacteria have deposited a purplish colouration of oxides.
The undersides of the rocks and the soil beneath are light in colour. Clearing away the surface rocks leaves a bright mark that lasts for centuries.
The dark rubble cleared away can be used to outline the lines in the drawings. Each Nazca line or figure is edged by a rock mound up to one metre high.
Some spectacular explanations for the lines have been proposed over the years. The criss-crossing of the lines, many forming rectangles, bear a striking resemblance to a modern airport. Erich von Daniken, the Swiss author, proposed that the lines represented runways or markings to facilitate aliens landing their spacecraft. The craft would have to be very light and of vertical landing/take-off design to negotiate the soft earth of the desert floor.
Other explanations have proposed that the lines were drawn to be admired by the gods, or by alien-astronauts flying overhead in hot-air balloons.
Reiche claims the markings are an ancient astronomical text. She has interpreted several of the animal figures as star maps, e.g. the monkey maps the position of key stars in the constellations Leo and Ursa Major. Each alignment, in her interpretation, signified a specific time of year and the overall pattern constituted a huge astronomical calendar. Reiche points to the practical need for such a calendar for an agrarian people living in arid conditions. One criticism of Reiche's interpretation is she assumes that the same stars and constellations that dominate the European picture of the sky were equally important to the ancient Nazca people. This is hardly likely. Andean natives today see the sky differently from Europeans, and some features such as Ursa Major are hardly visible above the Nazca horizon.
The hypothesis of Nazca Lines as giant observatory was tested in 1968 by Gerald Hawkins, an astronomer from Boston University. Five years earlier Hawkins announced that the monoliths at Stonehenge were erected as an observatory to predict eclipses. He fed the positions of the Nazca lines into a computer programmed to calculate how many lines coincided with an important astronomical event. The number of lines of astronomical significance did not exceed the number that would result from blind chance.
On the other hand, an exercise analogous to that performed by Hawkins found that 50 per cent more of the lines than would be expected by chance if they were randomly oriented pointed towards sunrise and sunset in late October. October is an important time in the agricultural cycle of the valleys that border the Nazca plain, a time when rain falls to swell the flow of the rivers and underground irrigation canals that join the oases at the desert edge.
The lines may have indicated the sunrise/sunset positions that accurately predict the increased availability of water.
Another theory was proposed by the explorer Tony Morrison. He investigated the old folkways of the people of the Andes mountains and uncovered a tradition of wayside shrines linked by straight paths along which the faithful would travel praying and meditating. Morrison suggests the Nazca lines served a similar purpose, but on a huge scale. The symbols might have been special areas for religious ceremonies.
Many of the Nazca lines are perfectly straight for miles. How was this achieved? An endless straight line can easily be guided by two people using wooden stakes. A stake is driven into the ground and one person stays with it. The second person drives another stake into the ground some distance away and walks farther on with a third stake. The first person sights along the straight line joining the first two stakes and guides the other person in the exact placing of the third stake.
The second person now walks on carrying another stake. The first person proceeds to the second stake, sights along it and the third stake and thus guides the position of the fourth stake. And so on.
A symbol could be drawn on the desert by first drawing it at a reasonable size and using a grid system to divide it up. The symbol could then be drawn by redrawing a scaled-up grid on the ground and working on the individual grid squares one at a time.
William Reville is a senior lecturer in biochemistry and director of microscopy at UCC