264 THE POPULAR SCIENCE MONTHLY . 



ence is unlikely to be a constant one ; and, looking for variation, 

 we may ask Avhat is its amount, and under what conditions does it 

 occur ? 



2. Difference in Mass and in Complexity. The comparisons be- 

 tween the sexes, of course, admit of subdivisions parallel to those 

 made in comparisons between the races. Relative mental mass and 

 relative mental complexity have chiefly to be observed. Assuming 

 that the great inequality in the cost of reproduction to the two sexes 

 is the cause of unlikeness in mental mass, as in physical mass, this 

 diiference may be studied in connection with reproductive difierences 

 presented by the various races, in respect of the ages at which repro- 

 duction commences, and the period over which it lasts. An allied in- 

 quiry may be joined with this ; namely, how far the mental develop- 

 ments of the two sexes are affected by their relative habits in respect 

 to food and physical exertion? In many of the lower races, the 

 women, treated with great brutality, are physically very inferior to 

 the men ; excess of labor and defect of nutrition being apparently 

 the combined causes. Is any arrest of mental development simulta- 

 neously caused ? 



3. Variatioii of the Differences. If the unlikeness, physical and 

 mental, of the sexes is not constant, then, supposing all races have 

 diverged from one original stock, it follows that there must have been 

 transmission of accumulated differences to those of the same sex in 

 posterity. If, for instance, the prehistoric type of man was beardless, 

 then the production of a bearded variety implies that within that va- 

 riety the males continued to transmit an increasing amount of beard 

 to descendants of the same sex. This limitation of heredity by sex, 

 shown us in multitudinous ways throughout the animal kingdom, 

 probably applies to the cerebral structures as much as to other struct- 

 ures. Hence the question, Do not the mental natures of the sexes in 

 alien types of man diverge in unlike ways and degrees ? 



4. Causes of the Dfferences. Is any relation to be traced between 

 this variable difference and the variable parts the sexes play in the 

 business of life ? Assuming the cumulative effects of habit on func- 

 tion and structure, as well as the limitation of heredity by sex, it is to 

 be expected that, if in any society the activities of one sex, generation 

 after generation, differ from those of the other, there will arise sexixal 

 adaptations of mind. Some instances in illustration may be named. 

 Among the Africans of Loango and other districts, as also among 

 some of the Indian Hill-tribes, the men and women are strongly con- 

 trasted as respectively inert and energetic : the industry of the women 

 having apparently become so natural to them that no coercion is 

 needed. Of course, such facts suggest an extensive series of ques- 

 tions. Limitation of heredity by sex may account both for those 

 sexual differences of mind which distinguish men and women in all 

 races and for those which distinguish them in each race, or each so- 



