RETROGRESSION AND REGRESSION 135 



past ancestry, and unless very careful selection has taken place, 

 the mean of that ancestry is probably not far from that of the 

 general population." 1 The induction here is that there exists a 

 tendency for exceptional groups to return towards mediocrity 

 unless Natural Selection interferes. The deduction is that on 

 cessation of selection the race or species tends to remain stable. 

 But when we appeal to reality the evidence is massive that cessa- 

 sion of selection results in retrogression. Here again no attempt 

 is made to demonstrate that the Laws of Regression and Retro- 

 gression are in accord, or, if not in accord, in what particular the 

 latter is wrong. The truth appears to be that, though regression 

 results in a levelling up to the specific mean as well as a levelling 

 down to it, yet, in a degree that varies in different species and 

 characters according to the rapidity of the antecedent progression, 

 the tendency to level down is somewhat greater than the tendency 

 to level up. The point aimed at is not the specific mean, but below 

 it. Consequently this point tends continually to fall unless 

 rendered stable or raised by selection. Therefore regression is but 

 the first phase of retrogression. As a rule, however, the latter 

 proceeds so slowly, by such imperceptible gradations, that its 

 detection is far beyond the reach of the laboratory, which can 

 examine, at most, only a few generations. 



226. Formerly some men of science maintained that Natural 

 Selection had no real existence, or at least had not been de- 

 monstrated. Natural Selection implies a selective mortality, which 

 our acquaintance with the lives of wild plants and animals is not 

 sufficiently intimate to prove. It was shown, however, that 

 stringent and unmistakable selection occurs amongst all races of 

 human beings, the only ' wild ' types which we are in a position to 

 observe with the requisite degree of thoroughness. 2 In England, for 

 example, we are being selected by tuberculosis and other maladies ; 

 in Africa, malaria plays the same part ; in India dysentery, and so 

 forth. The immediate result is that individuals weak against any 

 lethal disease are weeded out wherever it is present. The remote 

 result is that every race is resistant to every disease in proportion to 

 the length and severity of its past experience of it. Therefore the 

 evidence of Natural Selection followed by evolution is plain and 



1 Pearson, Grammar of Science (Ed. 1900), p. 456. 



2 See The Present Evolution of Man, 1896. The common notion that man is 

 not a ' wild ' or natural type is, of course, nonsense. He is not under the care 

 of and has not been artificially selected by any other type. Civilization has 

 altered the conditions under which he lives, and therefore the incidence of 

 selection and the direction of evolution, but that is all. It has not altered the 

 ' laws ' of heredity for him. 



