Data for the Problem of Evolution in Man. 



129 



We conclude at once that these joints in the right hand are very 

 sensibly larger than in the left. In every case there is a difference of 

 about 0*02, and this is many times larger than the probable error of 

 the difference, i.e., s /2 x 0*003 about. 



We might, therefore, conclude that the right hand is larger than the 

 left. This conclusion is directly opposed to that of W. Pfitzner :* he 

 asserts that there is no quantitative difference between right and left 

 for the simple anatomical parts of the hand skeleton. His own 

 measurements, however, really do show such a sensible difference for 

 the first phalange. All then we assert at present is that the first joint 

 and the first phalange are larger in the right than in the left hand of 

 women. We prefer to state no more sweeping view at present as to 

 other parts of the hand, however strong our private opinion may be. 



4. Variability of the Hand. — The following are the numerical results 

 reached : — 



Table II. 



Standard deviation. Coefficient of variation. 



Ri 0-1055 ±0-0021 4*6945 ± 0*0954 



Rii 0-1133 ±0-0023 4-7432 ± 0*0964 



Eiii 0-1091 ±0-0022 4*9345 ± 0-0100 



Riv 0-0986 ±0-0020 5-3537 ±0*0109 



Li 0*1088 ±0*0022 4*8917 ± 0*0994 



Lii 0*1137 ±0*0023 4*8033 ±0*0976 



Liii 0*1082 ±0*0022 4*9481 ±0*0101 



Liv 0*0975 ±0*0020 5*3614 ±0*0109 



If we were to judge by absolute variations the index and middle 

 fingers of the right hand are less, the ring and little fingers more 

 variable than those of the left hand. But if we use the more 

 reasonable coefficient of variation, we see that all the first joints for 

 the left hand are more variable than the corresponding joints for the 

 right hand, and this is precisely what we might expect if there be 

 greater adaptation by selection, or by use of the right hand. The 

 greater the selection, the less the variability. 



In the left hand the relative order of variability (as measured by 

 the coefficient of variation) is that of the relative size of the fingers : 

 in the right hand this is slightly modified.! The work has been care- 



* Dr. G-ustav Schwalbe's ' Morphologische Arbeiten'; W. Pfitzner. 'Das 

 Menschliche Extrernitatenskelet,' Bd. I, pp. 21—35, and Bd. II, pp. 99—106, 

 1892 and 1893. 



t The divergence is not one on which real stress can be laid considering the 

 probable error of the coefficient of variation. The hand confirms what we have 

 already learnt from the long bones ("Roy. Soc. Proc.,' vol. 61, pp. 347 — 348), 

 that 5 per cent, closely measures the variability of the chief parts of the human 

 body. 



VOL. LXV. L 



