Large monumental cemeteries line the shores of Kenya’s Lake Turkana: hundreds of tightly packed graves beneath round stone platforms ringed with boulders and basalt columns, each flanked by its own chain of smaller stone circles and cairns. To learn more about the people who built it, archaeologists recently excavated parts of the largest and oldest of these monuments and surveyed the site with ground-penetrating radar. The results suggest that Kenya’s ancient herders constructed them as a communal effort to cope with an unstable environment and a shifting cultural frontier.

A crowded ancient cemetery

Around 5,000 years ago (according to radiocarbon dating of burials), people started clearing away deep drifts of beach sand on a peninsula jutting out into Lake Turkana, digging down to the sandstone bedrock and shoring up the sides with large, flat slabs of sandstone. Then they started digging into the soft sandstone floor of the 30-meter-wide pit, carving out shallow, closely spaced graves.

Archaeologist Elisabeth Hildebrand of Stony Brook University and the Turkana Basin Institute and her colleagues excavated a 2m by 2m test area in the center of the pit and another at the edge. Based on the number of people buried in just those two small spaces, they estimate that the crowded cemetery at the heart of the Lothagam North Pillar Site holds at least 580 graves.

When the pits had all been filled, people added another layer of burials on top—this time with bodies in all sorts of positions and orientations, as if people were trying to fit as many burials as possible into the available space in the pit. After a few centuries of burials had filled the pit, they capped it off with sediment and covered the whole mound with uniformly sized black pebbles.

This doesn't seem to have been a resting place reserved for the wealthy or high-ranking elites—in fact, Hildebrand and her colleagues say the society that built Lothagam North may not have had much social hierarchy at all. Both men and women are buried here, infants and older adults.

Most of them took jewelry and other personal adornments to their graves: strands of ostrich eggshell or vibrantly colored stone beads, hippopotamus ivory rings or bangles, or headpieces made from latticed arrangements of animal teeth. The objects a person is buried with often reveal something about their wealth, occupation, or social standing, but none of the burials stood out as especially elaborate, and Hildebrand and her colleagues say the few people who didn’t seem to have jewelry or other grave goods probably owe that to poor preservation rather than to paupers’ burials.

Mobile herders and monumental architects

So who were these people? Archaeologists still aren’t entirely sure.

"What’s so exciting about this cemetery is that it’s one of the only clues we have regarding who these people were and how they lived," study co-author Steven Goldstein, an archaeologist at the Max Planck Institute for the Science of Human History, told Ars Technica. "The normal habitation sites where people lived are notoriously hard to find, and the only one we really know about is a place called Dongodien on the opposite side of Lake Turkana from Lothagam. From what was found there, livestock was the most important part of their economy, but they also relied on hunting and fishing." But it doesn’t seem likely that they’re related to the modern-day Turkana people, who only arrived in the area a few hundred years ago, according to their own oral histories.

“The Turkana regard the pillar sites, which they call Namoratunga or ‘people of stone,’ as ancient dancers who were turned into stone when they inadvertently laughed at a disguised deity who visited them. People will often place a stone on the pillars when passing as a sign of respect,” study co-author Elizabeth Sawchuk, an archaeologist at Stony Brook University and the Max Planck Institute for the Science of Human Historytold Ars. “We worked with local Turkana communities throughout these excavations to ensure this work was done respectfully and with their support and engagement.”

The next phase of that work is an effort to determine whether there’s a genetic link between the people buried at Lothagam North and any other Holocene archaeological human remains from East Africa. The results will help archaeologists understand why herding reached East Africa: because herders moved into the area, because local people adopted the practice, or a combination of both. Sawchuk plans to publish the results of that work later this year.

Elizabeth Sawchuk 2018

Elizabeth Sawchuk 2018

Elizabeth Sawchuk 2018



Elizabeth Sawchuk 2018

Elizabeth Sawchuk 2018

Landmarks in a changing landscape

Meanwhile, if Hildebrand and her colleagues are correct about these ancient herders being more-or-less egalitarian, without an elite ruling class, that could challenge some long-standing assumptions about which cultures tend to build monuments and why. Anthropologists and historians usually associate monumental efforts like Lothagam North with settled agricultural societies—the kind that have built up enough of a food surplus that some people can specialize in stone carving or building stone circles, or at least so the community can spare some farmers' labor for part of the year. And typically they also assume that it takes a ruling elite to organize such massive projects and keep people at work.

The ancient herders of East Africa don't seem to have met either of those criteria: they roamed a broader landscape to tend their herds of cattle, goats, and sheep, and they seem to have built Lothagam North and the other five pillar sites in the area during a time of uncertainty.

When the African Humid Period, five centuries of relatively high rainfall, came to an end around 5,000 years ago, the drier climate would have made grazing harder for livestock. It also drastically altered the landscape itself; over the course of the next few centuries, water levels in Lake Turkana dropped by around 55 meters, which moved the shoreline of the lake. All of this meant that good fishing sites and good grazing patches were constantly shifting.

Hildebrand and her colleagues suggest that the pillar sites served as a focal point for communities in need of landmarks, stability, and a clear sense of identity. These monumental cemeteries could also have been the sites of other ceremonial and social gatherings, which might have given people an opportunity to share information about grazing lands and trade goods like obsidian, for which the nearest source is about 100km away from Lothagam North across the lake.

A project that spanned generations

The stone platform at Lothagam North is ringed by basalt boulders, while 48 basalt pillars, about 1.5 meters tall, line its eastern side, although many of them have fallen over. The pillars formed naturally but were moved into place. The largest weigh up to 800kg, and the builders of Lothagam North would have had to maneuver them over a kilometer of rough terrain.

"It’s not a long distance, particularly considering these people were probably highly mobile, but it involved going up and down a series of steep rocky hills. We have to climb just one of those hills to get up to the site, and it’s definitely a challenge without hauling rocks!" Sawchuk said. And since modern East African herders don't use their livestock as beasts of burden, Hildebrand and her colleagues assume their ancient forerunners didn't either.

A series of cairns and stone circles stretches inland along the peninsula, turning the peninsula into a monumental landscape. Kenya's ancient herders buried people in the cairns and stone circles as well, and the radiocarbon dates for at least one of the stone circle graves falls within the same range as the graves beneath the main platform, which means these smaller structures weren't just add-ons because the main cemetery had run out of space.

"We don’t know why some people were buried in the platform versus the stone circles," Sawchuk told Ars. "We are hoping more research helps us understand differences between the cairns/circles and main burial cavities."

Unanswered questions

According to radiocarbon dating, it took between 450 to 900 years to finish construction at the site, ending by around 4,100 years ago. It's not clear how long after this people kept using the sites, but they seem to have been abandoned long before the Turkana moved into the area.

"We do know that they were capped in an orderly fashion with stone mounds and pillars instead of being hastily abandoned," Sawchuck told Ars. "They may have continued to be important places after the cemeteries were completed and people turned to other forms of burial." In fact, radiocarbon dating indicates that the cemetery was full and capped with pebbles well before the rest of the work at the site was finished.

One of the other things archaeologists still want to understand about the pillar cemeteries of Lake Turkana is whether—or, more likely, how—these sites were connected.

"This remains a big question—how do the different pillar sites relate to one another, and how much did people move around the lake? Given the architectural similarities, we predict that the pillar site builders were in contact and may have been part of the same culture/population," Sawchuk said. But most of what archaeologists know about the cemeteries and the people who built them comes from Lothagam North, so Hildebrand and her colleagues are hoping to gain more insight from the other sites, especially another of the earliest ones, called Jarigole, on the far side of the lake.

PNAS, 2018. DOI: 10.1073/pnas.1721975115 (About DOIs).

An earlier version of this article attributed quotes to Elisabeth Hildebrand which should have been attributed to Elizabeth Sawchuk and Steven Goldstein; that has been corrected.