For the first time, archaeologists have described an intact underwater offering made by the Inca (opens in new tab) people, deposited into Lake Titicaca in the Andes (opens in new tab) about 500 years ago.
The discovery hints that evidence of other important Incan rituals, such as human sacrifices, may also lurk underwater.
The Spanish recorded the Incan practice of placing offerings in water in the 16th century, and this offering — a stone box — is the first such object to be discovered in one piece. It holds a small gold bracelet and a shell carved to resemble an alpaca or llama. The box may have also contained human blood, according to a new study.
Related: Photos: Digging up Incan fortresses (opens in new tab)
Lake Titicaca extends into what is now Bolivia and Peru; it is one of South America's largest lakes, and is known for its importance to the Incas. Incan origin myths name the lake as the birthplace of the sun, and a ceremonial complex of Incan shrines and temples once stood on the lake's Isla del Sol, or Island of the Sun.
In 1977, amateur divers from Japan found several stone boxes underwater on the Khoa reef near the island's temple complex. Their age and location suggested that the objects had been placed in the lake by the Incas for ritual purposes. More boxes were recovered from the reef during dives in 1988 and 1992, but nearly all of the boxes were broken or had been looted.
Beginning in 2012, an international team of archaeologists extended the search for submerged artifacts in Lake Titicaca, and in 2014, experts discovered the undamaged box at the bottom of a reef near K'ayaka Island in the southeastern part of the lake, the study authors reported.(opens in new tab)
The rectangular box was sculpted from a volcanic rock called andesite and measures 1.2 feet (0.4 meters) long, and 0.9 feet (0.3 m) wide. It was tightly sealed with a circular stone plug but was not watertight. Perforations and grooves on the short sides of the box likely once held ropes that were used to lower it into the water — a practice described in Spanish records, according to the study.
Once recovered, the box wasn't opened immediately.
"We opened the stone box in our field laboratory in the presence of various municipal and local Indigenous community authorities," the researchers said.
Inside, they identified a rolled sheet of gold measuring 0.98 inches (25 millimeters) long that looked like a miniature version of a bracelet commonly worn by Incan noblemen. Next to the bracelet was an alpaca-like animal figurine carved from a mollusk shell, measuring 1.1 inches (28 mm) long. Such carved figures are found alongside similar gold bracelets at other Incan ritual sites; together, these symbols of animals and wealth may represent an offering of thanks for prosperity and good fortune, the scientists wrote.(opens in new tab)
However, these types of offerings have also been associated with human sacrifices to appease or glorify the gods, according to the study.
Records from the 17th century, written by Alonso Ramos Gavilán, an Augustinian cleric, describe Incan rituals at Lake Titicaca in which "the blood of children and animals was placed in stone boxes and lowered from rafts into the lake with the aid of ropes," whereupon clouds of blood rising from the boxes would tint the lake red, the researchers reported.
"It is certainly possible that blood was included in the stone boxes, and future residue analyses may verify this possibility," the scientists said.
The box's careful placement at a reef that was distant from the Island of the Sun further suggests that the entire lake — not just the temple complex — served an important role in Incan rituals. And it's possible that other bodies of water were similarly revered by the Incas and were used as a site for depositing offerings, the researchers said in a statement. Such offerings may be lurking in other submerged locations, "such as rivers, springs, lagoons or the Pacific Ocean," the researchers said.
The findings were published online Aug. 3 in the journal Antiquity.
Originally published on Live Science.