What's required in a brain, for it to do a caring thing, is the ability to see a situation and anticipate an outcome if you were to do something. It's a similar sort of skill to the use of a tool to achieve an abjective - a brain that can work out that if some stick or stone is used in this or that way it will alter a situation beneficially (from the point of view of the tool user) is the sort of brain that can project an outcome in a caring situation too.
Given that we see tool use in some intelligent animals (albeit relatively rudimentary when compared with humans), and we can also see acts of what appears to be kindness which appears to be in response to a dire situation for the recipient, we might reasonably conclude that the motivation is a thought-through response to aleviate peril or suffering.
Jan's article about Dolphins pretty much confirms this (although, because of their body type dolphins don't exhibit tool use, there are other indications that they are very intelligent creatures capable of anticipating the consequences of their actions). It doesn't benefit Dolphins from any evolutionary point of view, to help humans. It will not be a simple, instictive response, done without thought or measure, because it's a situation that would occur very rarely in the wild and therefore could not have evolved in response to an environmental pressure. So it must be a response which has been decided on the basis of thought, with a projection of a better outcome for the human, and no benefit (other than satisfaction) for the Dolphin.