But this is exactly where things get tricky. When we compare different animals, we have to take into account that their typical bodies and movement patterns differ. When the animal walks upright like humans and birds, the longitudinal axis of its body is vertical. If it moves on all fours, it will align horizontally. This means that the process of ‘spinning’ can involve very different types of movement. For an animal that is on all fours, this means that its long axis is tilted to one side or the other. When it turns two-legged, it rotates around its longitudinal axis, which itself remains stationary. Both types of rotation are possible for dolphins and other animals moving in three-dimensional space.
When we started studying lateralization in dolphins, we were careful to separate the two types of locomotion. But we’ve always been at odds over what we call a right or left turn. After much discussion and arguments, we realized that we had discovered a strange peculiarity of human perception: humans clearly interpret the direction of rotation in different ways, depending on the direction of the animal.
It takes a new turn
To identify this issue, you can do the following: Stop and turn right. Then lie on your stomach and turn right again. In an upright position, most people who do this task move their right shoulder toward their back. In a horizontal position, turn your right shoulder toward your chest or forward. So it completes the exact opposite rotation. (And in case you were wondering, no, you cannot solve the problem by specifying rotation clockwise or counterclockwise. Replacing “right” with “clockwise” in the above example will give you the same result.)
To date, all studies of lateral division of rotational motions have examined a single species in a given direction, For example the human beingWho turns around or whaleWho jumps and turns around. So the topic never came up. This also means that opposite symbols were used in the published data – depending on how the animals were directed. The rotation, in which the right side of the animal moves forward, is usually symbolized as left or counterclockwise – if it is human or young. In the case of dolphins and whales, on the other hand, this represents a right-hand rotation or a clockwise direction. If we want to examine the lateral direction of rotation across different species, we must agree on the direction of rotation. This means we need a new coding system.