Science Spin July 2009

Dolphins, sorting facts from fiction

The DCP carries out long-term, longitudinal observations of dolphins, researches the cognition, communication and social behaviours of this popular cetacean. The researchers at DCP put equal emphasis on another type of communication, outreach work, and to educate other scientists, and the wider public, on their findings.

Justin Gregg, a doctoral student at the Trinity College School of Psychology, and has spent the last four years working with the DCP: "Part of what we do is publishing popular science accounts and communicating what it is that dolphin scientists do and have discovered. There's a lot of very strange information about dolphins which you can find. Some of it is harmless, you know the idea that dolphins are actually from outer space and have psychic powers. But some of it is sinister, saying that dolphins heal autism and making pseudoscientific claims that can cause quite a lot of harm to dolphins and to humans. So, we are keen to clear the air."

The DCP was founded in the late '90s by current director Kathleen Dudzinski, a US marine biologist. Dudzinski pioneered an underwater camera array that's used to investigate dolphin behaviour underwater by recording video and stereo audio. The camera equipment is used at DCP study locations dotted across the world, including wild dolphin populations off the coast of Japan and Bimini, the Bahamas, and captive populations in Honduras and Nassau, the Bahamas.

Justin came to the project in 2004. With a background in language and music - he studied linguistics at the University of Vermont and sound engineering and music technology at the Sound Training Centre, Dublin. Justin had an interest in learning about the use of language in animal species. "I really wanted to study communication behaviour in animals as I was quite interested, in a vague sense, in the evolution of language. I was very interested in the communication signals that animals use that might have something in common with human language."

COMMUNICATION

Justin carried out some background research and discovered that the area of dolphin behaviour was attracting curiosity in communication circles. Referential signalling, a behaviour common in humans but rare in animals, had come under the spotlight. There are different definitions for referential signalling but, in general, it relates to behaviour used by one animal to draw another animal's attention to something outside of their 'normal' world. Vervet monkeys, for example, can make sounds to highlight the presence of a predator such as snake or eagle to other monkeys.

Another type of referential signalling is the pointing gesture. It is something that humans use easily and frequently, but not animals. Dolphins are an exception. Justin explained: "Experiments have been carried out where a researcher would point to a ball and the dolphin would be able to follow that point over towards the ball. For animals, even dogs, it is very difficult to follow a point into the distance so the behaviour is quite rare in the animal kingdom. It's also strange that dolphins can do it because, one, they don't have hands or arms and, two, because they were able to do it on the very first trial, so it seems to be something that they had an innate ability to understand."

This, said Justin, triggered many questions for him and he was motivated to carry out a PhD thesis in the area. This brought him into contact with the DCP as Kathleen Dudzinski, alongside Howard Smith, Head of School of Psychology at TCD, agreed to be his co-supervisors.

ECHO-LOCATION

Referential signalling in dolphins is not an entirely new area of study. Research carried out in the mid-'90s by Mark Xitco and Herbert Roitblat, who worked with captive dolphins at the Epcot Center in Florida, set the scene for this behaviour. The work, which has since been corroborated by DCP scientists, suggested that dolphins could glean information from each other through behaviour known as 'eavesdropping'.

When dolphins need to know more about the environment around them, they produce a series of click sounds which, when they bounce back from objects in the water, make echoes. By listening to these echoes, a process known as echolocation, a dolphin can get an image of whatever is nearby - say a rock, boat or fish. Research has demonstrated that dolphins don't just listen to their own clicks, they can also tune in to the clicks of other dolphins in their vicinity. This 'eavesdropping' behaviour is thought to be the dolphin equivalent to pointing.

Justin wanted to take this work a step further. "There have been a lot of studies done in captivity but no-one really knows how dolphins use echolocation in the wild. So that's what I was in the water trying to figure out," he says. Working with a population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) based near a small volcanic rocky outcrop off the coast of Japan, Mikura Island, Justin would don wetsuit and record underwater dolphin behaviour for hours at a time.

The Japanese dolphin population was selected for the relaxed nature of its individual dolphins around people. Justin explained: "You have to find a group of wild dolphins that are habituated to the presence of humans, for example tourists or researchers, in the water. It takes years to build up the trust. It's the same reason why people go to visit gorillas in Rwanda - it takes a long time for the gorillas to finally ignore you, you're part of the scenery and they go about their social lives. The same's true for dolphins. I can name three or four sites in the world where you can jump in the water and the dolphins ignore you."

His results from the Mikura dolpin population of Japan have suggested that there are subtle changes in behaviour which indicate that one dolphin is listening in on information supplied by another. For example, an eavesdropping dolphin is more likely to stay silent and move their head position when they listen to the signal of the investigating dolphin.

Justin explained: "I waited until two dolphins approached me before recording their behaviour to see if one of them or both of them echolocates. I would also observe if there was a trend that one would echolocate and the other would remain still, just listen and kind of follow the head movement of the other. To some extent, this seems true."

POINTING

The research findings may have an impact on communication science outside of the animal world. Justin, who became the lead researcher in charge of the Japan site and is now Vice President of the DCP, said: "The ability to understand a pointing gesture is no trivial matter, and is often singled out as a skill exclusive to the human mind; part of the unique arsenal of cognitive aptitudes that makes us the wise ape." This has practical applications for human communication.

A lack in ability to interpret point gestures, for example, has been flagged as one of the criteria used in diagnosing autism. Could it be that new information yielded from non-human species could hold answers for those affected by such conditions? Justin said: "As we begin to understand how pointing comprehension, mind reading skills, and echolocation may be interconnected in the dolphin brain, we ultimately learn more about the human brain."

With the commitment and innovation shown by researchers involved in the DCP it is likely that the mysteries of the dolphin words will unfold over time. And, with these answers, we may learn more about ourselves. As Justin concluded: "Somewhere at the intersection of the dolphins' pointing skill and the limitations imposed by autism, lurks the answer to a bigger question about what makes us human."

 

Justin Gregg won third place in the 2008 Wellcome Trust and New Scientist essay competition for an account of his research with the DCP. To view his award-winning essay, 'Dolphin's get the point', click here.