Human Infancy and the Recapitulation Theory 77 



Thus the youth of mammals is not devoid of ancestral features. 

 These may be "recapitulatory" either because they resemble 

 features of the youthful period of the ancestor, or because they 

 represent the actual adult ancestral condition modified in descent. 

 It would be a matter for study in each case. Still, this does 

 not make youth essentially recapitulatory, for these features 

 are comparatively few when measured against the total make- 

 up of the young animal. They exist alongside others which 

 are adapted to the infantile condition as such, and in spite of 

 what is declared to be a close resemblance of young and adult 

 mammals, taking the group as a whole. 



3. Recapitulation and Human Infancy. 



Before undertaking a discussion of the relation of the theory 

 of recapitulation to human infancy — more especially to the mental 

 traits of infancy — it will be well to consider just what may be 

 properly understood by ancestral reference in this connection. 

 It is obvious, in the first place, that there is nothing to correspond 

 to palaeontological evidence, the court of last resort on the physi- 

 cal side, — unless something of value may be inferred from the 

 structure of fossil skulls. Ancestral allusions to racial mind 

 must be made in the main to what can be inferred legitimately 

 from objective behavior in the scale of living animals, and 

 since these animals are almost universally end-forms in a long 

 process of specialization away from common ancestors, it is 

 clear that inferences as to phyletic mentality are extremely 

 hazardous. If, however, a mental or physical trait peculiar 

 to infancy has a fairly well-defined homolog among lower animals 

 that may be regarded as closely related to probable ancestors, 

 there is ground for assuming an ancestral reference. If the case 

 is one of degree, there must be reasonable certainty of a greater 

 resemblance to the ancestral homolog than to the infant's own 

 adult condition. There will be no justification for assuming 

 an ancestral reference simply because an infantile trait shows 

 some analogy to any animal trait whatever, and surely none 

 merely because no prospective, adult, or adaptive reference 

 can be made. Biological utility is no longer a category of uni- 

 versal application. Heredity is now known to carry much more 

 than the materials of organic adaptations, having laws of its 



