There are various theories about how ancient society on Easter Island — a remote island 2,300 miles from Chile in the Pacific Ocean — collapsed. Some say the civilization burnt down all the trees and self-destructed, while others blame infighting, Western invaders or Polynesian rats. But the tools used to build 1,000 of the island’s iconic, stories-tall stone structures known as “moai” in Rapa Nui, the local language, reveal high-level collaboration.

Previously, the statues were thought to have been the work of a relatively small group of (extremely dedicated) craftsmen. In a study out Monday in Journal of Pacific Archaeology, researchers suggest they may have been the product of a more complex and sophisticated ancient society.

“For  everyone  to be using  one type of stone,  I believe they had to  collaborate. That’s why they  were so successful — they were  working together,” Dale Simpson, an archaeologist from the University of Queensland and the paper’s lead author, said in a statement. Through chemical analysis of 21 tools used to craft the statues, archaeologists say they found evidence that raw materials were shared from various regions on the island — evidence of collaboration.

The first people arrived on Easter Island in two canoes, according to oral tradition, about 900 years ago. The population rose into the thousands over the years, and according to Simpson, likely also had chiefs, priests, and workers who fished, farmed, and built the moai.Jo Anne Van Tilburg, an archaeologist and another of the study’s authors, said it was important not to jump to conclusions. “We can't know at this stage if the interaction was collaborative. It may also have been coercive in some way. Human behavior is complex.”