I remember reading or hearing something about this tune once. It was along the lines that the descending third (in music that uses the Western scale)is evocative because it points you in the direction of the "home" keynote (do) but doesn';t actually take you there. Somehow this catches the attention more than, say, a major third would, as this would take you right home and be less interesting.

Recently there was a radio programme about the composition of Somewhere Over the Rainbow, and it related how they were stuck for a middle section for the tune, and then they thought of that falling minor third that you'd use for calling a dog, repeated, and they'd got it.