Free time is a big factor and dolphins have an abundance of it. First, they dont sleep like we do but rather shut down one side of the brain for a few minutes at a time throughout the day. Rarely are both sides shut down. This is necessary because the dolphin needs to breathe air at least once every 8 minutes, usually 2-3. All it needs to do is eat a lot of fish and the rest of the time is spent socializing and playing.
Communication (intraspecies) is also necessary. Dolphins use a whistle language which is 10 times faster than our speech and 10 times higher frequency. Dolphins have repeated human speech although at the higher frequency and speed. It is amazing considering their vocalization apparatus as it would be comparable to humans repeating speech by playing on a trombone modulated to sound like speech! They find it very difficult to slow the speech down comparable to us.............................................talk................. ....................ing..................................ve......... .............................ry..................................... ................sl..........................ow...................... Its hard for us to talk that slow in real life and the dolphins probably find it the same way.
Another communications bonus is their sonar, which shows them the inside reactions of every other dolphin, human, fish, etc. around them much like ultrasound for a pregnant mother. Imagine knowing what everyone around you was feeling-happy, sad, angry. No one could lie or deceive. This is due to the physiological changes that occur within us when we think about things and it makes sense that it applies to dolphins. About their sonar, they can see if anyone is injured as well. I remember one story (in The Secret Language of Dolphins) where a woman was continually pushed until she left the pool. A minute or so later she collapsed in pain. When at the hospital she found she had bad internal bleeding (or something) which the dolphin must have seen and noticed the problem. As no one was around that could have removed her from the pool (the walls were 10 feet above waterline or so) her life was probably saved.
The only thing cetaceans don't have is a way of storing permanent data like written language. It could be memorized (if we are assuming they are intelligent, communicating creatures with stories of their own...) but not having a manipulatory organ can be a great disadvantage as it serves as a memory buffer (like for humans). One of my ideas is to develop a computer to interface to and act as a "thought tool" for the dolphin. It could also translate typed speech into a whistle language. Since they respond to sign and spoken commands, we only need to give them a method of communicating TO us to open many doors that are as yet untried.
As a side note to the above proposal, I know the idea would work as its been done with chimps. A research group called the Primate Cognition group (or something) had taught chimps to communcate with the trainers with a symbol based language and some with American Sign Language. The unexpected part came when they discovered the chimps were "talking" to each other with ASL when the trainers werent around! One mother even taught it to her baby, completely without training from the staff. True they had nothing profound to say but dolphins seem far more than the intelligence of mere chimps.
One last bit of food for thought. A group in Hawaii at the Sea Life Park did "self awareness" tests to see if dolphins were conscious of themselves. It appeared they were! The test was of a video monitor placed by an underwater viewscreen for the dolphin to watch. When it only played videotape of other dolphins they werent interested. But when connected to a video camera to function as a mirror, they "hammed it up", clapping their jaws and making funny head motions (and inviting others to watch, I believe). Another test was with the video camera from the side of the pool so the dolphin would see a side view of himself. They placed a white mark on his side, out of his visual range. He didnt act any different. But when they turned on the monitor so the dolphin could see himself from the side, and now see the white mark, he acted strangely: craning his neck to that side, trying to get a view of it, rubbing the side against things and cheching the monitor again, etc.
Well, this should give you something to chew on for a while so enjoy! :)
Mike Shawstad