John Lilly, who spent years working with dolphins, believed that they were smart enough to be cute and friendly to humans because they understood how dangerous we were.
Thanks for mentioning Lilly. His book on his studies of dolphins* was a good read when I picked it up a decade or so ago. The comparison of brain- to body-mass across humans, elephants, and dolphins was compelling, alone.
Most of the time the people think about how cute is a dolphin is misunderstanding the animal. If a Lion shows you the teeth, you don't think is a cute kitty, is angry!, but, hey, this dolphin that show us the teeth "is smiling"!. This "smile" is in fact an agressive display in the wild.
Being faster, well armed, and better fitted for water, a dolphin can avoid dangerous humans in the water any time he wants. In fact a lot of alone exemplars search for company, actively, even if is from humans, and are curious. Some dolphins simply like the human company, or the benefits derived of this, other not... at all.
These foxes actually share a good number of features with dogs and humans: it may be that, because dolphins are such social creatures, we perceive them as cute because they are more or less domesticated.
A suspected reason why domesticated animals cuter is the ideal that traits that are typically selected are traits found in youth. The general term for this is neoteny [1], which is where youthful traits are held on to into adult life.
Typical traits selected for are reduced aggression and increased docility. The hypothesis is that the animals that displayed these traits likely also had a variety of other relatively child-like traits, such as larger heads, larger foreheads (I guess this might be why dolphins look so darn cute), larger eyes, floppy ears, and etc - on the basis that the set of genes that control the development of adult traits are typically linked together.
The result being that as we selected for the tamest animals, we also selected those that were cuter. It's kind of circular in that traits that make things cute are typically those that are found as young - the young form of most animals sharing the same general 'cute' features.
One thing of note is that the concept of neoteny is often invoked to explain how humans diverged so rapidly from the other primates. If you accept that explanation, and take the idea a bit further, then you end up with a somewhat bizarre and perhaps disturbing idea that humans are actually the result of self-domesticating primates (obviously a gross over simplification... but kind of a fun thought to play around with).
Yes but dolphins are not selectively breeded for domestication. At all. They are anti-domesticated in fact.
If a killer whale attacks or kills a people in a zoo, (and this accidents happen) this whale is not killed and is maintained in breeding programs, as its sons. Too much expensive animal to lose its genes.
What's amazing about the silver fox domestication experiment was that it used ONE selection criteria - flight distance (the distance a human can approach an animal before it runs away) to do selective breeding. After tens of generations, the foxes were domesticated and most of the traits of a domesticated animals such as cuteness came along as side effects.
It was a great experiment showing a simple selection rule can generate complex evolution result.
