Why do Elephants have more memory?

Memory of elephants:

Elephants have relatively high and impressive encephalization quotient. Encephalization quotient is the ratio between the actual brain mass and predicated brain mass for an animal of a given size. In other words, the actual brain size is more than that of the predicted size of the brain. Elephants have EQ of about 1.88 whereas dogs and cat have 1.1 and 1 respectively. Humans have 7. There is a incident in Tennessee state of USA where the two elephants Jenny and Shirley worked together in a circus. When they reunited after 23 years, they become excited and started bellowing indicating that they remember each other. Scientific studies show that the elephants remember the way to drink water even after the years.