Lets Be More Like Elephants?

I was wondering why humans were the only known mammals who developed intelligence since we don't have the biggest brain - Elephants do. It turns out that elephants are more intelligent than I had given them credit for and are also altruistic animals. I came across this from Wikipedia that shows their, sometimes, good side.

"Elephants are thought to be highly altruistic animals that even aid other species, including humans, in distress. In India, an elephant was helping locals lift logs by following a truck and placing the logs in pre-dug holes upon instruction from the mahout (elephant trainer). At a certain hole, the elephant refused to lower the log. The mahout came to investigate the hold-up and noticed a dog sleeping in the hole. The elephant only lowered the log when the dog was gone. When an elephant is hurt, other elephants (even if they are unrelated) aid them.

Cynthia Moss has often seen elephants going out of their way to avoid hurting or killing a human, even when it was difficult for them (such as having to walk backwards to avoid a person). Joyce Poole documented an encounter told to her by Colin Francombe on Kuki Gallman's Laikipia Ranch. A ranch herder was out on his own with camels when he came across a family of elephants. The matriarch charged at him and knocked him over with her trunk, breaking one of his legs. In the evening, when he did not return, a search party was sent in a truck to find him. When the party discovered him, he was being guarded by an elephant. The animal charged the truck, so they shot over her and scared her away. The herdsman later told them that when he could not stand up, the elephant used her trunk to lift him under the shade of a tree. She guarded him for the day and would gently touch him with her trunk."

Source: http://en.wikipedia.org/wiki/Elephant_cognition

If the above is true then elephants do have a degree of intelligence in them but why hasn't it developed like ours? Some scientist believe that the brain has to a certain size in order for it to develop to the degree of intelligence we have. It's an interesting thought for sure but one that doesn't quite satisfy me...