Présentation de l'éditeur
The work of Dubois and of Lapicque (23) has done much to clear up this problem by defining the ratio of brain to body weights and Dubois coefficient of cephalization presents a possible means of accurately correlating cerebral development with intelligence. But the lack of any quantitative determination of differences in the complexity of behavior of different species of animals makes it impossible as yet to evaluate this coefficient. The work of Szymanski (12), Turner (13), and von Frisch (14) on learning in insects shows them little inferior to lower mammals, and among mammals we cannot say that a relatively higher brain weight is a certain indication of superior intelligence, since we have no sure measure of the latter. Within the single species the correlation is still less certain. Basset (14) found that a strain of rats of less than average brain weight was inferior in learning ability to a normal strain, but his data, as Paterson (17) has pointed out, are not statistically valid. Crude comparisons of the brain weights of superior, normal, and criminal men show the former groups as having slightly higher weights (D onaldson, 03), but are of doubtful significance because of the uncertainty of the evidence for a real difference in the complexity of the behavior of the groups (G oring, 13; Fernald, Hayes, and Dawley, 20). For ganglion cell number, as indicated by surface area of the cerebrum or degree of fissurization, the relationship is even less clear. The primates show a relatively greater surface area than lower mammals, and the anthropoids the greatest surface area of the primates, but, as Monakow (14) has pointed out, many of the ungulates show much greater fissurization of the cortex than carnivora with probably much higher intelligence, so that the exact significance of surface area The relation between learning ability and intelligence is by no
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