What other possible results could this heart-beat imprinting have？ It may, for example, explain why we insist on locating feelings of love in the heart rather than the head. As the song says: "You gotta have a heart!" It may also explain why mothers rock their babies to lull them to sleep. The rocking motion is carried on at about the same speed as the heart-beat, and once again it probably 'reminds' the infants of the rhythmic sensations they became so familiar with inside the womb, as the great heart of the mother pumped and thumped away above them.