Peaceful interactions rarely occur between a predator and prey. But researchers in Ethiopia caught wild wolves and monkeys called geladas intermixing without agression.

The seemingly tamed wild wolves just up and walk through the monkey herd, while the monkeys act like the wolves don't exist.

Other carnivores on Ethiopia's Guassa Plateau, feral dogs and servals mostly, hunt the gelada monkeys — it would seem that the wolves would be a natural predator as well. But instead researchers observed the two species happily intermixing for years.

This peaceful interaction could be similar to how dogs were first domesticated by humans. "The gelada case is comparable to what early domestication of dogs might have been like," study researcher Claudio Sillero, of the University of Oxford, told New Scientist's Bob Holmes.

From their observations, they think the mutual friendship helps the wolves hunt, by making rodents easier to spot and catch.

They reported the incident in the Journal of Mammalogy

An uncommon friendship

High up on the grassy Guassa Plateau 12,000 feet above sea level, gelada monkeys travel in herds up to 700 members strong. With long fangs, and wild manes of hair the gelada monkeys appear pretty vicious for an herbivore that likes to eat flowers and seeds. They share these grasslands with their main predators, servals and feral dogs, as well as wolves.

According to New Scientist:

"You can have a wolf and a gelada within a metre or two of each other and virtually ignoring each other for up to 2 hours at a time," says [study researche Vivek] Venkataraman. In contrast, the geladas flee immediately to cliffs for safety when they spot feral dogs, which approach aggressively and often prey on them.

When the wolves enter the gelada monkey herd, they alter their behavior to show the monkeys they aren't aggressive. Normally wolves run in a zig zag pattern or make rapid movements when searching for rodents. But when around monkeys they slow down to a more sedate stalk even when hunting.

And even more surprisingly, the wolves in the study don't try to eat the baby geladas — an easy-to-get meal.

There's always exceptions to the rule, of course, and during their observation period the researchers did observe one altercation: One of the wolves attacked a baby monkey. The adult geladas quickly mobbed the wolf, which dropped the baby monkey unharmed and ran off.

Primates have been observed to form associations with other animals, but, the authors write, these relationships are rare and often fleeting. In contrast, the gelada's relationship with the wolves is pretty stable — the researchers observed it over the course of years — and it doesn't appear to be ending anytime soon.

Research funded by National Geographic. Jeffrey Kerby

Why work together?

Other than engaging in fewer fights, were there other benefits to these co-habitating creatures? The researchers found that when these two species intermingle, the wolves can snatch up rodents about 40% more often than when hunting away from the monkeys.

Why? The researchers have two theories: Either the geladas flush rodents out of their homes, making them easy targets, or the rodents have trouble distinguishing between the two similarly sized and colored animals, and don't run away from the wolves.

While the wolves earn easier meals, the monkeys don't seem to benefit from having the wolves around. They don't scare away other predators that prey on geladas — the researchers saw feral dogs kill numerous monkeys during the study.

Historically wolves also tagged along behind another species: humans. Thousands of years ago researchers believe that wolves scavenged along the outskirts of human settlements or groups. While the humans probably killed aggressive wolves, the non-aggressive wolves were tolerated and eventually domesticated after people found value in them as hunters and possible companions.