As Figs [1], jgeralnik, and CWuestefeld [2] have pointed out there might also be a huge problem in their methodology.
Let's say that we have created an immersive environment for a mouse, so that we can replay what the mouse would see if it saw a piece of cheese similar to the way they've played back that sonar ping. If the mouse starts running towards it/"identifies" it, would that mean the mouse has developed a complex visual language? No, it would just mean that the mouse has seen the cheese!
Unless they have conclusive proof that a dolphin directly sends a pre-modulated imprint of the object it just revealed, then their experiment is probably making a similar mistake somewhere or the other.
I think that there is a better way to design this experiment. One of the better ways to conclusively test this hypothesis would be to teach a dolphin tool use to get food and see if it can teach others to do the same. To ensure that simple imitation isn't going on, we could keep a hydrophone immersed for the entire duration and continually record what's happening.
If other dolphins learn how to use the tool, then I would move on to the next step and see if they can work together in teams. If they display co-ordination then we would have conclusive proof of language use.
So, we already know they can coordinate, but it's not clear if there's communication ("hey, let's do XYZ") or if they're just very quick at imitation ("Hmm, looks like Akeakamai is going to do XYZ, better do XYZ").
Perhaps what we could do is set up an arena and force them to work together as a team. If we design the experiment with care then we might be able to settle the question of imitation vs. communication.
For example if we hide food beneath inside a container and put several such containers in a grid then we could see if they co-ordinate the search. We could control for imitation by making the pool pitch black and covering the dolphin's eyes, thus forcing them to use echolocation extensively, which we should be able to capture. If we can track the direction and the nature of the clicks as well as the position and subsequent actions of the dolphins after making them, then we might be able to answer this question.
Let's say that we have created an immersive environment for a mouse, so that we can replay what the mouse would see if it saw a piece of cheese similar to the way they've played back that sonar ping. If the mouse starts running towards it/"identifies" it, would that mean the mouse has developed a complex visual language? No, it would just mean that the mouse has seen the cheese!
Unless they have conclusive proof that a dolphin directly sends a pre-modulated imprint of the object it just revealed, then their experiment is probably making a similar mistake somewhere or the other.
I think that there is a better way to design this experiment. One of the better ways to conclusively test this hypothesis would be to teach a dolphin tool use to get food and see if it can teach others to do the same. To ensure that simple imitation isn't going on, we could keep a hydrophone immersed for the entire duration and continually record what's happening.
If other dolphins learn how to use the tool, then I would move on to the next step and see if they can work together in teams. If they display co-ordination then we would have conclusive proof of language use.
Has anyone ever done rigorous research like this?
[1] http://news.ycombinator.com/item?id=3315023 [2] http://news.ycombinator.com/item?id=3314522