The book contains a number of references to Matthew’s “circumstance-adaptive” law, but only in relation to the races of man (i.e. microevolution, not macroevolution). For example, in Note E of the appendix (pp.224-225, titled “Native Race adaptation”), Matthew notes that natural selection may not favour the more moral or civilized, but simply the most fecund:
In cases where two races exist in a country, under any thing approaching to equal law, it is not the most moral or most civilized which increases the fastest, or which will ultimately prevail. This is being exemplified in Ireland, and in Great Britain, where the Milesian race is fast gaining ground, and also in Hungary, where the Sclavonic race is gradually overwhelming the Magyar, by superior powers of increase. In both cases the conquered are reconquering, although lower in the scale of civilization.
Likewise, in the section on Australia (p.101), a rather unlikely hypothesis regarding the evolution of skull thickness is advanced. The connection between skull thickness and stupidity is one example of the racism that pervades the book, but also of interest is the final sentence that links back to the British nobility – another group that Matthew did not think highly of:
When two tribes quarrel, they go out, at least in the New South Wales district, and give fair battle. Alternately, an individual on each side steps forward, stands with the head bent a little down, and is struck upon the crown of the head thus exposed, by an individual of the other party with a club, and this is continued regularly till one party is put hors de combat. This has the certain effect to destroy all those who have skulls inclining to thin, and carried on for many ages, as it in all probability has been (the customs of savages being very permanent), it must have exerted a selecting influence – the thin-skulled falling prematurely, and the thick-skulled remaining for breeders, to render them a thick-skulled race, which they literally are, their skull being nearly double the thickness of the European skull, and able to bear the blow of a club which would split the skull of any other man. Granting that the thick-skulled are really more stupid than the thin, which, only the thick-skulled, we think, will doubt, this must act to lower the mental capacity of the race. Besides, even the concussions may exert an injurious effect upon the intellect, which may become constitutional. Perhaps, it may be argued, that the similar chivalric practice of tilting at each other’s heads at tournaments may have exerted a similar influence in this country.