All over the world, people greet, talk, eat, dance and celebrate according to their own cultural practices. We’re not the only species with such traditions. Chimpanzees have rich cultural traditions that determine how they forage for food, communicate, groom each other and wield tools. Other species with their own local customs, including orang utans, monkeys, dolphins and killer whales, are all united by their vaunted intelligence. But another mammal with a comparatively smaller brain has just joined this cultural club – the banded mongoose.
Corsin Muller from the University of Exeter gave wild mongooses a plastic shell containing some food (like a reverse Kinder egg). He found that adults preferred to break into the shells using one of two possible tactics, and that they passed on these traditions to their pups.
The results earn some kudos for the humble mongoose, but they’re important because our evidence for animal traditions has always come from studies that compared the practices of wild populations, or that ran carefully controlled experiments in captive groups. This is the first time that anyone has used experiments to show that wild mammals pass on traditions by imitating one another.
Banded mongooses live in large groups of up to 40 individuals, who cooperate to find food and raise their young. Muller worked with five such groups in Uganda’s Queen Elizabeth National Park. Banded mongooses eat an eclectic menu of insects, centipedes, small reptiles, eggs and even mice. Many of their snacks come in a hard shell that needs to be cracked and mongooses do so either by biting them or smashing them against a stone or tree trunk.
Individuals have clear preferences about these two techniques. When Muller gave the adults his plastic shell, containing a mix of rice and fish, he found that some were exclusive biters, others only smashed and yet others used a combination. Critically, they were stuck in their ways. When Muller tested them three months later, they each showed the same preferences.
He also found these adults transferred their preferences to the pups who watched them. Banded mongoose pups form exclusive one-to-one associations with specific adults who act as their mentors. These adults are usually young males, who aren’t necessarily related to the pup, and the youngster will aggressively monopolise the attentions of these chaperones.
Around 2-4 months after the adults infiltrated their Kinder surprises, Muller gave their attendant pups (now independent) their own eggs to break into. Even though none of them had seen the toy eggs in the intervening time, they showed a significant preference for the technique that their mentors had used. Those who saw an adult bite the toys open did the same themselves; those whose mentors liked to smash copied that strategy instead; and those whose mentors had ignored their toy eggs were themselves uninterested. These preferences even persisted as the pups grew into adults.
Muller’s study expands on experiments with other captive species in a number of ways. In finding the same trend in all five groups of mongooses, he added some valuable replication to his study, which is often missing from experiments that focus on one group of captive animals. Muller showed that multiple traditions can coexist within a single population. And he showed that animals don’t need big brains to pass on traditions across the generations. It may be that such traditions are more commonplace than previously thought.
Reference: Current Biology http://dx.doi.org/10.1016/j.cub.2010.04.037
Photo by Reini68; video by Corsin Muller
More on animal cultures