Sir./

A few years ago an idea occurred to me which I have several times since submitted to the Criticism of Anatomists but hitherto without being able to elicit from them anything positive either for or against the idea. I therefore take the liberty of describing it to you as it seems to me to have an important bearing on the Question of the “Descent of Man” and so far as I know it is quite new.

When a man is walking at a moderate speed with his arms freely swinging by his side his right arm moves forward with his left leg and his left arm simultaneously with his right leg. This alternate movement is gone through also by the limbs of Quadrupeds. In them however it is essential but in man it is not and does not in any way assist in his locomotion but is frequently a hindrance unless prevented. Witness the position of the Arms in men who are running quickly, they are then drawn up and held closely to the side. Men without arms or with only one arm can moreover walk quite easily so that it seems to me that the movement of the upper limbs alternately with the lower in the way just mentioned is due to a rudimentary structure once more fully developed when the upper limbs like the lower were used for the purposes of progression as a child even now uses them before it has learned to walk—¹

Such is the idea. Possibly you may see in it what I only think I see.

Yours truly | J. D. Kendall