Human stick figures, some of them rowing boats, are painted on walls at Djulirri, a rock-art site in northern Australia.
The figures are thought to represent Makassans, indigenous people from the Indonesian
island of Sulawesi.
Such paintings indicate that Aborigines had extensive relationships with their neighbors, possibly hundreds of years before the British began settling Australia in the late 1700s.
However, the nature of those relationships may not have been amicable, according to team member Sally May, a rock art expert from Griffith University.
For example, many of the sites are "full of images of violence, boxing scenes, [and] spears," she said.
Photograph by Rick Stevens