Figure 1.

An example of how we scored the similarity of the song motifs produced by a father and one of its sons. Song notes considered to be similar received the same letter; degree of similarity between each of the notes of the father’s song and the corresponding note in the son’s song is given by the similarity score, which appears under the son’s song motif. In this case 14 of the father’s 15 notes were present in the son’s song, but only 13 of them received a score high enough to qualify as imitation. The son’s note C′ is very similar to the father’s note C but transposed in order. Overall similarity between the two songs was 86.6%. See text for details.