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On the Plane of Self Consciousness IV - 2

According to this law the energy-the power of exciting vision-of the red rays is several thousand times as great as the energy of the violet, and there is a regular and rapid decrease of energy as we pass down the spectrum from red to violet. It is plain that if there has been such a thing as a growing perfection in the sense of vision in virtue of which, from being insensible to colour the eye became gradually sensible of it, red would necessarily be the first colour perceived, then yellow, then green, and so on to violet; and this is exactly what both ancient literature and etymology tell us took place.

The comparative moderness of the colour sense is further attested by the large number of persons in all countries who are what is called colour-blind-that is persons who are at the present day entirely or partially without colour sense. " Wilson's assertion that probably one in five and twenty is colour-blind long remained doubted because not proved in reference to sufficiently large numbers.
Till we had comparison methods, and principally- Hohngren's, no satisfactory data could be obtained. His in proper hands so quickly decides a case that tests have already been made in thousands of persons.

Based on at least two hundred thousand examinations is the result that four per cent of males are colour blind in greater or less degree, and one-fourth of one per cent of females." This would make one case of colour-blindness to every forty-seven persons. The degree of universality of the colour sense in race is, of course, an important fact in estimating its degree of evolution as compared with other races.

In this connection the following facts are of interest: In Japan among 1.200 soldiers 1.58 per cent, were red-blind, and 0.833 per cent, green-blind. Among 373 boys 1 per cent were red-blind; among 270 girls 0.4 per cent. Among 596 men examined by Dr. Berry, of Kyoto, 5.45 per cent. showed defective colour sense. 

Among the Japanese, as a whole the percentage of colour blindness is less than in Europeans or Americans. Among 796 Chinese examined in various places no cases of colour-blindness were found, but there was a tendency often seen to mix green and blue. This peculiarity was brought out with much greater emphasis by Dr. Fielde, of Swastow, China, who examined 1,200 Chinese of both sexes, using Thompson's wool tests.

Among the 600 women only 1. The percentage of colour-blindness among Chinamen is, then, about 3 per cent., and does not vary greatly from that of Europeans." In colour-blindness the general vision is not affected; the individual distinguishes light and shade, form and distance, as well as do other persons. This also goes to show that the colour sense is more superficial, less fundamental, and probably therefore acquired later than the other powers that belong to the function of sight. For a person could not lose one of the more, fundamental elements of vision (the sense of visual form, for instance) and retain the other sight faculties unimpaired.

Colour-blindness is an fact an instance of what is calculated atavism, or relapse to a condition which was normal in the ancestry of the individual, but which does not properly belong to the species at the time in which he lives. The frequency of this relapse (estimated, as we have seen, to occur in one person out of every forty-seven) indicates that the colour sense is comparatively modern; for atavatism is more frequent in inverse proportion to the length of time that elapsed since the organ or function lost or improperly taken on (as the case may be) has (in one case) normally existed in the race or (in other) been discarded in the process of evolution.

The rationale of this law (which will be again referred to) is obvious: it depends upon the simple fact that the longer any organ or function has been in existence in a race the more certainly will it be inherited. The existence of colour-blindness, then, in so large a percentage of the population shows that the colour sense is a modern faculty.

The relative visibility of the different coloured light rays makes it certain that if the colour sense was acquired it would undoubtedly have been so in the order in which philologists claim it actually was acquired, and the concurrence of these two sets of facts, the one drawn from natural philosophy and the other from etymology, together with the fact of colour-blindness, is so striking that it seems impossible to refuse assent to the conclusions reached.

Reference: Cosmic Consciousness: A Study in The Evolution of The Human Mind: Richard Maurice Bucke