Mobbing a group of lions for their food is a risky move, but for hungry hyenas, participation is worth it.

A new study details the emergence and role of cooperative behavior in confrontations between spotted hyenas and lions. Describing the emergence of cooperation is key to understanding social evolution.

"When hyenas mob during hyena-lion interactions, there is significant risk of injury by participating in this cooperative behavior," lead researcher Kenna Lehmann, an integrative biology doctoral candidate at Michigan State University, said in a news release. "However, when they gang-up like this, they are more likely to win control of the food. This suggests that cooperative behavior increases fitness in hyenas."

As a new video reveals, gangs of hyenas take a fairly structured approach to mob behavior, cackling, growling, snarling and lunging in unison, individuals acting as a single unit, slowly inching forward until they've chased their adversaries away.

Food is often their reward, but in their analysis of multiple interactions between groups of lions and hyenas, Michigan State scientists found the number of hyenas present was more predictive of mob behavior than the presence of fresh meat.

The latest analysis -- detailed in the journal Current Zoology -- was made possible by 27 years worth of data collected by Michigan State's Mara Hyena Project. It's the first time cooperative mob behavior has been studied among lions and hyenas.

"This work would not have been possible without the long-term database," said study co-author Tracy Montgomery, also a doctoral candidate. "Not only did it allow us to demonstrate that mobbing likely increases fitness in hyenas, but it also will help us identify factors that will help predict whether this cooperative behavior will occur. It also has set the stage for additional studies."

Having confirmed the evolutionary benefit of mob behavior among hyenas, scientists will now turn their attention to how a hyena's age, sex and social standing affects mob participation. Scientists also want to find out if the duties of aggression are equally shared by mob participants, or if there are cheaters who reap the rewards without risk or sacrifice.