Who's more intelligent?

#interesting

For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much – the wheel, New York, wars, and so on – while all the dolphins had ever done was muck about in the water having a good time.

But conversely, the dolphins had always believed that they were far more intelligent than man for precisely the same reasons.

-– The Hitchhiker’s Guide to the Galaxy