Courtesy of the British Library

Many cultures have collected and displayed human remains, such as the Mandan tribe of North Dakota (pictured above). The Catholic church has long preserved the body parts of saints, known as “relics,” because of their presumed spiritual significance.

But Scottish anthropologist Farlan Crannach was thrown for a loop when he lived with the Tchalimba people. The obscure island of Koka is only a spec in the Indonesian archipelago, and Tchalimba language and customs bear no relation to neighboring ethnic groups. When Crannach arrived in 1920, he counted only 312 Tchalimba people on the 50-square-mile island.

“After two weeks among the Tchalimba,” wrote Crannach, “they were keen to my company, and thus they offered me a gift: a human skull gilt in silver.”

Everything about this gift was surprising: Where did the skull come from? And how had they covered the surface in silver?

“In every aspect of their lives, the Tchalimba are Stone Age people and would seem incapable of smelting ore into metal,” Crannach noted. “I believe the skull is very old and is only intact on account of its metallic coating.”

Right away, Crannach sensed something was strange about the skull. When he measured it, he noted that the cranium was elongated, much like a Neanderthal’s, but not to the same extreme.

Once Crannach had learned enough of the Tchalimba language, he tried to prod the villagers for more information.

“As they soon revealed, every hut in the village, and therefore every family, possesses at least one such skull, and they are exchanged as a form of currency, whereby a wife may be purchased for a skull, unless she is very comely, thence she might fetch two or three skulls.”

When he asked about the origin of the skulls, the villagers were tight-lipped. No one seemed willing to discuss the history of the island.

“They would take to staring at the ground, as if overwrought with shame or regret,” Crannach wrote. “I believe that their forefathers fought for possession of the island against some other breed of men, and they resolved to hunt their rivals to extinction. If it was in fact the Tchalimba who glazed the skulls with silver, that knowledge has since been forgotten.”

Crannach has proposed to call the new species Homo kokais, but his peers have requested further study.