Why Did Ancient Indigenous Groups in Brazil Hunt Sharks?

In a snowy forest near Montreal, Martin Lominy aimed his bow at a butchered hog, hanging from twine between two trees. A craftsman who recreates ancient tools, Lominy was helping archaeologists test whether or not arrows tipped with shark teeth could pierce game.

“I figured that’s not going to work,” he says. “They’re all going to explode on impact.”

But the experimental arrows whizzed through the meat, only busting if they collided with a rib bone. The archaeologists behind the experiment, Simon-Pierre Gilson of the Federal University of Santa Catarina, Brazil, and Christian Gates St-Pierre of the University of Montreal, added bow hunting to their growing list of shark tooth uses. In other tests, they proved the razor-sharp teeth, fixed to sticks, worked for myriad tasks, from scaling fish to sawing wood.

Knowing this, the researchers moved one step closer to overturning a long-standing idea about past hunter-gatherers of Brazil. Nineteenth-century scholars had assumed the coastal inhabitants scraped by on a diet of shellfish and other easy catch and that they only nabbed big kills, like sharks, when old, ill or wounded ones washed up on shore. This view held for over a century, despite the fact that many thousands of shark teeth have surfaced at Brazilian seaside settlements, spanning from 8,000 years ago to the 1500s.

Now, Gilson and colleagues have advanced an alternative explanation in a pair of papers forthcoming in the Journal of Archaeological Science: Reports. Based on their experiments and analyses of centuries-old teeth, they contend that multiple Indigenous communities were skilled shark hunters, who slayed the creatures for food, raw materials and perhaps something even more valuable: social and spiritual prestige.

“I don’t think you enter in the water to catch a shark just for catching a shark,” says Gilson, a postdoctoral researcher.

Daniela Klokler, an archaeologist at Brazil’s Federal University of Sergipe, was not involved in the studies, but backs their stance. Klokler has analyzed much older shark remains, left several millennia ago by coastal Indigenous populations who erected massive mounds made from clamshells and other debris. Some of these so-called sambaquis, or shell mounds, rose as high as seven-story buildings, and many contained human burials. Archaeologists think the more than 2,000 sambaquis dotting Brazil’s coast served as ceremonial monuments, built and used by numerous native groups between 500 and 8,000 years ago.

The shell mound builders, researched by Klokler, may or may not have been the direct ancestors of the inhabitants responsible for the 500-to-700 year old specimens studied by Gilson. Yet, she reached the same conclusion about sharks’ importance as food, tool components and cultural icons. “These teeth are not by chance at the sites,” she says.

Gilson began his project in 2015, after he sorted through animal bones piled in storage at the Federal University of Santa Catarina’s museum. In box after box, he discovered hoards of shark teeth. And thousands came from Rio do Meio, a little-known site on Santa Catarina Island, off Brazil’s southern coast.

Archaeologists don’t know who exactly built the 500-to-700-year-old site. Today, few Indigenous communities remain on the coast, as European colonizers killed or forced most Native groups farther inland. But when the Portuguese arrived in 1500, roughly 900,000 Native Americans inhabited the Atlantic shores of present-day Brazil. Most groups, like the Tupinambá, spoke Tupí languages. Based on 16th-century sources, artifacts and DNA evidence, it’s thought that the Tupinambá expelled many Macro-Jê speaking groups from the coast to the continent’s interior not long before Europeans landed. Though, some Macro-Jê communities remained coast-dwellers into the colonial era.

Although archaeologists cannot say which Native culture occupied Rio do Meio, they have a good idea how that community used the site. In the 1990s, archaeologists hurriedly excavated Rio do Meio because the beachfront spot was threatened by real estate development. Digging an area roughly the size of a basketball court, they uncovered pottery, stone tools, fire pits and trash heaps harboring hundreds of thousands of sea creature remains as well as fewer mammal, bird and reptile bones. Unlike most sites in the region, Rio do Meio clearly was not a shell mound monument. With no signs of dwellings or graves there, archaeologists think the site served as a designated place for butchering and processing hunters’ daily catch.

Two decades after the archaeological dig, when Gilson gazed into the boxes of teeth, he immediately wanted to know why shark was so abundant at Rio do Meio. Archaeologists frequently recover shark remains at ancient coastal sites in Brazil. But in many cases, only teeth remain, looking like they were strung into jewelry for the dead: Rows of teeth, with holes drilled into the roots, accompany human skeletons in sambaqui graves. However, other clues indicate the coastal inhabitants also dined on shark. Earlier studies, conducted between by Klokler and others have measured elemental signals in human bones buried in shell mounds between 500 and 5,000 years old. The results reveal the ancient residents ate animals high on the food chain—apex predators like shark.

From the collection gathered at Rio do Meio, Gilson examined 3,900 shark specimens. Although that was less than 10 percent of the total collection of shark remains, the animal’s perishable nature made it a difficult endeavor. The carnivorous fish leave little behind because their skeletons comprise mostly soft cartilage, rather than bone. The only parts that preserved, that Gilson could analyze, were teeth and the disk-shaped centers of vertebrae.

Based on subtle differences in tooth and vertebra appearance, Gilson identified at least 47 sharks from 15 different species, including hammerhead, tiger and great white—creatures that grow more than ten feet long and weigh over 1,000 pounds. Given the variety and abundance of the fishes, Gilson says the evidence is clear the residents were expert shark hunters.

He also noticed that nearly all the teeth belonged to large sharks, whereas 80 percent of the vertebrae came from young ones or smaller species. According to Gilson, this mismatch suggests the hunters deboned small fishes and discarded their skeletons on the spot. Meanwhile, behemoths were sliced into several chunks and taken home to cook with bones still inside—as traditional fishers in Brazil do today. This pattern, paired with the earlier studies measuring elemental signals, convinced Gilson that the coastal residents regularly dined on shark. In fact, comparing the shark bounty to other food scraps found at the site, he estimated that shark constituted between 54 and 75 percent of the meat eaten by the past inhabitants.

“Shark was really important in the food intake for this population,” says Gilson, who reports the findings in the first of the Journal of Archaeological Science: Reports papers, coauthored with his doctoral supervisor, archaeologist Andrea Lessa of the Federal University of Rio de Janeiro.

Gabriel Prieto, a University of Florida archaeologist who has analyzed shark remains from Peruvian sites, is not surprised by the high counts. “People will go after the big game and the big game is not only in the land, but also in the sea,” he says. According to Prieto, archaeologists have tended to overlook this dietary staple in part because shark remains rarely preserve—and when they are found, prove difficult to analyze.

But Gilson suspected sharks provided more than meals. After all, there were less vicious big fish to catch for dinner. European colonists, living in Brazil between the 15th and 18th centuries, wrote that Tupinambá and Goitacá peoples made arrow tips from shark teeth. If the specimens from Rio do Meio really functioned as weapons or tools, they would likely still have microscopic nicks, etched during their use. Moreover, these marks may be distinctive for different activities, like stripping wood or slicing hide. In theory, Gilson and colleagues could read the scratches on a tooth’s surface to understand what kinds of tasks it performed.

Many archaeologists have successfully applied this approach, called microwear analysis, to artifacts made of stone. But few have considered looking for microwear on shark teeth. To try it, Gilson headed north to collaborate with Montreal-based St-Pierre, a microwear expert, and Lominy of Technologies Autochtones, the artifact reproduction and archaeology education company. After training as an archaeologist and working in museums, Lominy founded the company in 2005 to help educational institutions teach the public about technologies and tools used by Native Americans.

Gilson and colleagues wanted see what shark teeth could do, and if those activities left distinctive marks on tooth surfaces. In addition to the arrows shot in the snowy forest, Lominy crafted a variety of implements tested in 14 experiments. The researchers used the teeth-tools to scrape, saw, puncture and cut different materials like wood, bone, hide and fish.

There was a learning curve for working with shark teeth. “We have some scars on our hands,” says St-Pierre.

Overall, the teeth-tools performed their jobs and picked up distinctive microwear or fractures in the process. Gilson and St-Pierre established a key—for linking use scars to specific tasks—that researchers can apply to archaeological specimens. For the Rio do Meio teeth, the archeologists have detected a variety of uses, including a few they think were shot as arrows.

University of Arizona archaeologist Suzanne Fish, who was not involved in the study, commends the team’s efforts to elucidate shark uses. “They’ve done a lot of innovative things,” says Fish, a professor emerita who has researched sambaquis in Brazil. “Those authors are just exhaustive in terms of thinking about every possible variable related to sharks.”

In the papers, Gilson and colleagues question the idea that shark-teeth found in graves were all adornments. The rows of teeth could have once been attached to wooden shafts, which since decomposed. They may have been essential tools that hunters wanted to take to the afterlife. Klokler thinks this is highly probable. In many of the burials she’s analyzed, “we see a line with the shark teeth. I have the impression they could be composite tools.” And the reason shark teeth were made into tools and ornaments, and sometimes taken to the grave: “I think that [sharks are] totally associated with another realm,” she says.

The researchers are most intrigued by this potential shark role—the hypothesis that the creatures were spiritually or culturally significant for coastal residents. When analyzing the microscopic scratches etched on the teeth, St-Pierre says, “We look at the surface, but we're interested in more deeper questions.”

Even for experienced shark hunters, killing a massive predator would have been a memorable, status-raising feat. “It's probably something that people would talk about, would tell stories about around the fire,” says St-Pierre. There “must be thousands of stories that are lost that we will never hear.”