A father and son pair of independent researchers used images captured from space to identify what may be the largest known geometric figures made by humans, and the first to be reported from the Indian subcontinent, reports a new study.
The enigmatic lines, known as geoglyphs, decorate the ground near the town of Boha, India, and add up a total distance of about 30 miles. The largest geoglyph in the cluster, named Boha 1, is an asymmetric spiral line that measures some 7.5 miles and lies right next to another multi-patterned geoglyph, Boha 2, that is almost as long. These dimensions “have no equivalent worldwide,” and their purpose and meaning remains unknown, according to a new study in the journal Archaeological Research in Asia.
“After extensive research, we consider the Boha geoglyphs to be the largest abstract and organically arranged man-made geometric figures discovered so far,” said Carlo and Yohann Oetheimer, the father-son team who discovered the lines, in the study.
Close-up views of the lines. Image: Carlo & Yohann Oetheimer, Archaeological Research in Asia, 2021
The Nazca Lines of southern Peru, perhaps the most recognizable geoglyphs in the world, contain dozens of different figures that encompass a larger area than the Boha figures. But no single Nazca line is even half as long as either Boha 1 and 2, said the Oetheimers, who first spotted the figures on Google Earth and conducted a field study in the area during December 2016.
Karsten Lambers, an associate professor of archaeological computer science at Leiden University, couldn’t confirm that the Indian geoglyphs are the largest discovered worldwide, but said that in some ways, that measurement is beside the point.
“From a social and cultural perspective, this aspect is not really relevant, because it is safe to assume that whoever built those geoglyphs was unaware of their relative size on a global scale,” Lambers noted in an email.
Many of the most iconic geoglyphs in the world, including the Nazca Lines and England’s White Horse of Uffington, date back thousands of years, but the new study suggests the Boha figures have a more recent origin within the past few centuries. Getting a firmer read on the many unresolved mysteries about the patterns, including their age and cultural purpose, will require much more fieldwork and further engagement with local peoples.
“We did talk with locals and with shepherds about the lines but no one could answer our questions,” Carlo Oetheimer said in an email. “We still need to complete our study” which will involve “going back to India, making an anthropological survey and bringing all the equipment in order to date the geoglyphs.”
The team plans to publish another study that will summarize the results of this forthcoming expedition.
Lambers, who is an expert on South American geoglyphs, also highlighted the importance of follow-up research that might establish the “spatial and environmental context” of the Boha lines, including iconographic studies, archaeological surveys, and recordings of human activity associated with the figures.
“From my own geoglyph studies, I know that they can only be understood in their particular cultural, social, and historical context,” he said. “So anything to establish that context will help.”
Carlo and Yohann Oetheimer first noticed the geoglyphs during an exhaustive survey of the Thar Desert, which stretches across India’s northwest border with Pakistan, using satellite imagery from Google Earth. Initially, the team identified eight sites that appeared to contain geoglyphs, but onsite analysis revealed that four of them are associated with tree plantations, while three remain inconclusive.
Boha 1 and 2 reconstructed from images taken by the unmanned aerial vehicle (UAV) at an elevation of 100 meters. Image: Carlo & Yohann Oetheimer, Archaeological Research in Asia, 2021
One site east of Boha, in contrast, is significantly different from the rest: The lines in this area are enormous, uniquely patterned, and do not appear to be associated with any plantations. The Boha 1 spiral stands out as the ultimate giant of the cluster, but Boha 2 is arguably stranger, as it includes a serpentine line, a small spiral, and a huge sequence of subparallel straight lines connected by rounded U-shaped turns (the “boustrophedon”). The lines linked to these two main figures add up to almost 16 miles, but there are also smaller geoglyphs in the area that reveal other puzzling abstract designs.
The Oetheimers estimate that the lines are at least 150-years-old based on the vegetation that has grown over them, among other factors, and they plan to use thermoluminescence dating to pin down a more precise age in the future. The team also noted that the geoglyphs coincide with the location of intriguing archaeological artifacts that might be associated with the figures, including cairns, memorial stones, and nine monoliths of various shapes and sizes, with the tallest standing more than five feet high, underscoring another possible avenue of future research.
The geoglyphs may have been etched into the desert using a camel-drawn plow according to the study, but the motivation for making them remains the biggest and most tantalizing enigma. The region is too flat to appreciably observe the figures from a height, casting doubt on the efficacy of the lines as landmarks. Though the researchers emphasize that much more work needs to be done, including efforts to protect the geoglyphs from erosion, they speculate that the figures may have a religious or cosmological interpretation.
“At this stage of the research, we remain convinced that these unique geoglyphs are closely connected to their geographical and cultural context, and possibly contain a universal message linked to the Sacred and the cosmos,” concluded the Oetheimers.