52 POPULAR SCIENCE MONTHLY 



THE EULE OP THE ROAD 



By GEORGE M. GOULD, M.D. 



PHILADELPHIA, PA. 



THE localization through war and barter of the cerebral centers of 

 speech and writing (and hence of intellect) of 98 per cent, of 

 the population in the left half-brain is the cause of right-handedness. 1 

 The increase of the necessary differentiation of bodily and mental 

 function by the coordination of associated cerebral centers has resulted 

 in a general right-handedness, right-eyedness, etc., the data by vision, 

 audition, and for action of the right leg and foot for associated function, 

 compelling a location of all these centers in the same left-brain and 

 closely linked with the determining faculty of speech and writing. With 

 the two per cent, of left-handed, the reverse of all this takes place. 

 The mystery of the origin of right-handedness is thus cleared up. 

 With this explanation manifest the other concurrent mystery of the 

 rule of the road is of easy solution. Eight-handedness, plus the variant 

 circumstances of civilization, the reaction of the right-handed organ- 

 ism to the environment (in the language of evolution), explains all 

 the puzzles of the rule of the road. 



Primitive war, as Homer, chivalry, and present-day savage customs 

 demonstrate, regardless of the number of combatants, was a matter of 

 individual encounter, of hand-to-hand conflict. Even when archery, 

 and throwing of spears, javelins, etc., came into use the essential in- 

 dividualism was not changed, and the shielding of the left side, and 

 aggressive use of the right hand continued. All military tactics and 

 drill of numbers was then established as right-handed, down to the 

 most minute particular — and so continues, indeed, although the flung 

 weapon weighs a thousand pounds instead of one or two pounds, and is 

 thrown five miles instead of twenty or fifty feet. After the Trojan 

 war, chariots fell more and more into disuse, and cavalry began to take 

 their place, but this in no way changed the evolution of right-handed 

 tactics. In Alexander's time the right flank of the phalanx was the 

 post of honor, called the head, the left the tail, and marches and 

 movements were made by the right. The commander had his station 

 on the right. So strongly established was right-handedness as early 

 as the half-legendary Amazonian times, that the Amazon had her right 

 breast excised in order that she might hurl the javelin and shoot 

 the arrow with greater freedom and accuracy. 



1 See Popular Science Monthly, August, 1904. 



