§ 8 Motor Activity
Extraordinary and ape-like agility has frequently been noted among criminals. Every one is familiar with the daring feats of agility by which prisoners frequently escape scatheless from the hands of their guardians. This characteristic appears to be sometimes favoured by unusual length of arm. A thief, incendiary, violator, and murderer, examined by Marandon de Monthyel, showed little abnormal or criminal in his physical character, except an extraordinary agility.
Left-handedness has, by instinct or from accurate observation, been regarded with disfavour in the proverbial sayings of many nations. It is decidedly common among criminals. Examining 81 normal persons, Marro found 70 right-handed, 7 left-handed, and 4 ambidextrous. Examining 190 working-men, he only found 6 left-handed. Altogether the proportion of normal left-handed and ambidextrous persons was 6.2 per cent. Among criminals, on the other hand, with the single exception of highwaymen, the proportion of left-handed and ambidextrous persons was in every case higher. Among 40 assassins in 17.5 per cent.; among 7 incendiaries in 28.5 per cent.; among 44 burglars in 18.1 percent. This corresponds with a greater sensory obtuseness, which has also been observed on the right side among criminals. It is also interesting to note the ambidextrous tendency among children, savages, and idiots.
With the dynamometer, also, there appears to be a slightly greater prevalence of excess of the left hand over the right, judging from Marro’s experiences. It may be of interest to note here that among normal persons the proportion in which the left hand is stronger than the right is by no means small. Thus at the International Exhibition in London in 1884 observations made under Mr. Galton’s superintendence on 400 male adults—artisans, clerks, professional men, etc.—between the ages of twenty-three and twenty-six, showed that in 253 cases the right hand was stronger than the left in squeezing power; in 147 the left was stronger; in 28 both hands were equal. If we divide the individuals thus examined according to occupation the results vary curiously. Of 18 chemists, in 12 the right hand was stronger, in 5 the left, in 1 both were equal. Of 9 carpenters and joiners, in 4 the right hand was stronger, in 3 the left, in 2 both were equal. Of 87 clerks, in 52 the right hand was stronger, in 29 the left, in 6 both were equal. Of 9 medical men, in 5 the right hand was stronger, in 4 the left. Of 7 clergymen and ministers, in 3 the right hand was stronger, in 3 the left, in 1 both were equal. The high proportion of right-handed squeezers among the chemists is no doubt due to the effects of occupation, to the constant practice of gripping heavy bottles with the right hand. Occupation also, no doubt, among the carpenters and joiners, favours squeezing power in the left hand. The factor of occupation is less obvious among clerks, but would no doubt favour the right hand, and among these the proportion keeps very close to the average among the 400. The doctors are almost as left-handed in this respect as the carpenters, though the result can scarcely be influenced by occupation; while the clergymen, who are certainly most free from the influence of occupation in this respect, are the most left-handed of all, although here the figures are too small to allow of any very reliable results.
It seems that sufficient care has not yet been taken to determine what constitutes left-handedness. The relative strength of the two hands is not enough to decide this, for mancinism, or left-sidedness, is a matter of relative skill as well as of relative strength. It is quite possible for a person to be left-handed in some respects, right-handed in others; thus (as happens to be the case with the present writer) he may be right-handed in regard to all those actions which are exercised habitually and socially, or which are the result of training, and left-handed in all other respects. In such a case there appears to be a natural tendency to left-sidedness, which is controlled and concealed by training, but which takes every opportunity to assert itself in more unguarded directions. It appears to me that the act of throwing a stone, an act requiring delicate nervous adjustment as well as muscular force, and which is not subjected to the influence of artificial training, is for practical purposes the most convenient and accurate test for determining left-handedness. This was the test adopted by Clapham and Clarke; they found that 6 per cent. of the 500 criminals examined were left-handed.39
Ottolenghi has recently investigated the anatomical mancinism of criminals. At the suggestion of Lombroso, he has measured with Bertillon’s instruments, which give the maximum of precision, the length of the hands, the middle fingers, and the feet in 100 criminals and 50 normal persons. Differences of less than a millimetre he disregarded. He found that while the right hand was longer in 14 per cent. of the normal persons, it was so in only 5 per cent. of the criminals generally, and in none of the thieves and pickpockets. In 35 per cent. of the pickpockets the left hand was longer as against 11 per cent. in the normal persons. Very similar results came out in regard to the fingers. In 38 per cent. of the normal persons the right foot was longer, in only 27 per cent. of the criminals; in this respect, however, the pickpockets (35 per cent.) most nearly approach the normal, while those convicted of wounding, who in regard to the hand are nearest to the normal, are in this respect farthest from the normal. In 15 per cent. of the normal persons the left foot was longer, in 35 per cent. of the criminals, including 55 per cent. of the cases for wounding, and in 56 per cent. of the sexual offenders. It should be added that this anatomical mancinism is not necessarily related with motor mancinism.40
Anomalies of the tendon reflex of the knee are very common among criminals; they are either exaggerated or, very frequently, absent. Lombroso found feeble tendon reflexes especially common among thieves, and a very large proportion of exaggerated tendon reflexes among sexual offenders. Marro also found the highest proportion of exaggerated reflexes (the enormous proportion of 40 per cent.) among sexual offenders. There was an alcoholic or insane parentage among 79 per cent. of those with exaggerated reflexes.