A vervet monkey considering corn. (Photo by tullis / CC BY 2.0)
What do monkeys and whales have in common? Not much—besides a tendency to latch onto certain fads. Last week, two separate studies of monkeys and whales fueled the argument that animals’ adoption of some lasting behavioral 'fads' amounts to something we could call ‘culture’. What the researchers found is touted as the most powerful evidence we have that animals are indeed cultured—at least to a degree.
The definition of culture is rather fuzzy and hard to pin down, but generally scientists agree it amounts to behaviors that are developed by an initiator and spread throughout a population. In this way, a behavior becomes an established tradition, and helps form the overall ‘culture’ of a population. This pathway has been used to explain how humans discovered and shared the ability to strike up a fire for instance.
But what’s been difficult is figuring out just how much culture animals exhibit—or whether they exhibit it at all. Some of the most prominent studies to date have taken stock of orangutans, which seem to have unique behaviors that are tied to the specific groups they come from, potentially signaling the taught and learnt behavior that is the hallmark of culture. Now, vervet monkeys and right whales have been added to the research pool.
The first of last week’s studies comes out of a game reserve in South Africa, where vervet monkeys were the focus. Over a period of months, researchers conducted an experiment to see whether they could essentially condition groups of monkeys into adopting a behavior, so providing evidence that cultural transmission exists in animals too.
Honing in on four groups of vervets, the researchers displayed two crates of corn in each group—one lot dyed pink, and the other dyed blue. In two of the monkey groups, the pink corn was made bitter and unpalatable; in the other two, the reverse was true. After a period of months, the monkeys in all four groups demonstrated a clear preference for the tasty stuff, while they uniformly shunned the bitter corn.
But it was with the birth of new baby vervets during that period that the study got interesting. Babies copied their mothers, and across the four groups always chose the tastier fare. This provided evidence of “potent social learning,” paper co-author Andrew Whiten told LiveScience. The plot thickened further as researchers observed young roving male monkeys shifting from one group to another. When these males switched from a group that coveted one hue of corn to a group that preferred the other, most changed their original preference for the color preferred by the new group. This suggests that the monkeys are instruments and benefactors of cultural transmission. “Some of the ways of learning that we have thought were distinctly human are more broadly shared across nonhuman primates,” Whiten said.
The findings were made even more potent by those demonstrated in the second paper last week, which focused on humpback whales in Maine. Usually, humpbacks have been recorded feeding by circling their prey in a ring of bubbles. That was the standard method—until one innovative thinker came along in 1980, and started whacking the surface of the water with its tail before blowing rings of bubbles—a practice now known as ‘lobtailing’. It’s thought to shock certain types of prey enough that, in combination with the bubble blowing, fish are more easily caught.
But until now, there hasn’t been any powerful evidence to suggest that this behavior was spreading. A group of marine scientists plowed through an enormous Maine database of sightings documenting whale behavior, and which stretched back almost 30 years. Noting instances of observed lobtailing, and the proximity between whales that exhibited the technique, they plugged the information into a computer that showed how lobtail feeding was likely to have spread.
A whale lobtailing (Photo by A.Davey / CC BY 2.0)
Their mathematical model showed that almost 40% of the humpback population had adopted the behavior, and that almost 90% of the population was thought to have done so by ‘learning’ it from another whale. “It was very, very clear that cultural transmission was important in the spread of the behavior,” said one study author Luke Rendell to the blog, Not Exactly Rocket Science.
Together, the two studies suggest that it’s not genetics alone that drives behavior, but the influence of learning and transmission as well. While the resulting culture is vastly removed from our own, Carel van Schaik, an orangutan researcher who was not associated with the study said to Science that it heralds a new era in animal culture research. The “back-to-back publication marks the moment where we can finally move on to discuss the implications of culture in animals,” he said.