Do elephants really have good memories? Or is that just a saying?
In fact, a study on elephant memory shows that having a strong memory helps elephants survive in the wild. Scientists studying elephants in Tanzania's Tarangire National Park in Africa knew that some elephants lived through a terrible drought from 1958 to 1961. Now cut to 1993, when there's a second severe drought. Some elephant groups left the park, but only those with members who were old enough to have possibly remembered the earlier drought. The group that stayed in the park was composed of younger elephants. The elephants that left the park in 1993 were better able to survive; that group lost only 10% of their calves. But the group that stuck it out lost 40% of its young.
So in this case, at least, evolution selects for elephants that have memories strong enough to remember stuff from their childhood. For elephants, memory is a survival tool.