In the jungles of Sulawesi, an Indonesian island, primatologist Maura Tyrrell crouches to study the behavior of a crested black macaque, an endangered Old World monkey species. Tyrrell believes the monkeys -- highly intelligent, playful and engaging -- can shed light on the evolution of early human social structures.

Specifically, Tyrrell and her ongoing research suggests coalition-building behaviors among crested black males -- relationships and alliances forged in various competitive contexts -- may have influenced (or at least explain) how and why early humans first interacted with each other.

"Coalition-building must have been very important in the development of the political and social structures of early humans," Tyrrell explained in a press release. "How, why and when these behaviors arose among primates may tell us something about later hominid (including human) social evolution."

The species, Macaca nigra, is one of 22 types of macaques, and (in addition to Sulawesi) is only found on one other Indonesian island. They are increasingly endangered as their shrinking habitat is taken over by farming and logging.

Tyrell hopes her research can show just how special the monkeys are.

"If I find that there are some elements of coalition behavior that are common to macaques, chimpanzees and humans," she added, "it may be that some aspects of human coalitionary behavior had their origins in the common ancestors of Old World monkeys, apes and humans."

Tyrrell, a PhD candidate at the University of Buffalo, has been studying the monkeys on and off since 2011. Thanks to a recent grant from the Leakey Foundation, she will be able to continue her research at Tangkoko Nature Reserve. The Leaker Foundation has supported the work of famed primatologists Dian Fossey and Jane Goodall.

Tyrell will soon return to Sulawesi to conduct a 15-month study of social relationships between 20 of the wild monkeys, several of them belonging to different troops.

"I want to create a clearer picture of social relationships among crested macaques to help broaden our understanding of how early human male alliances may have evolved," Tyrrell said.