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SCIENCE 



[Vol. XX. No. 507 



SCIENCE: 



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BRAIN AND SKULL CORRELATIONS. 



BY S. V. CLEVENGER, M.D. 



The sizes and shapes of skulls afford only unsafe anthi-opologi- 

 cal and psychological generalizations. While the broad, the long, 

 and the round heads are characteristic of certain races, they are 

 even less invariably so than that the Mediterraneans are black- 

 haired and the Norse are " tow-headed." 



Heretofore crania have usually been studied as though it were 

 possible to detach them from everything else in the universe. 

 Their relationship to the contained brains, the phylogenetio and 

 embryological development of the brain and skull together, and 

 the influences of the one upon the other, have had but the most 

 superflcial consideration. The vast store of facts afforded us by 

 modern biology, undigested and disjointed though they be, will 

 yield unmistakal|le results if properly considered in relation to 

 cause and effect association. 



Every comparative anatomist has called attention to the occi- 

 pital position of the foramen magnum of the lower vertebrates, 

 and the tendency of this foramen to occupy a position farther 

 fortvard in the ascending scale of the mammalia, until, in the 

 primates, it is near, or at, the centre of the base of the skull. 



In the Journal of Nervous and Mental Diseases, April, 1880, in 

 an article entitled "Sulcus Rolando and Intelligence," I called at- 

 tention to the different positions occupied by this fissure in differ- 

 ent brains, showing that the sulcus of Rolando was placed farther 

 backward in the adult than in the younger animal, and that it 

 formed the posterior boundary of the frontal lobe, which, devel- 

 oping as the intelligence was greater, pressed backward upon the 

 parietal and occipital brain, causing the cerebellum to be covered 

 by the cerebrum ; the lesser size of the frontal lobes allowing the 

 brain to fall forward in its case, leaving the cerebellum of quad- 

 rupeds uncovered, and this same pressure from before backward, 

 projecting the temporal from the occipital lobe, and the temporal, 

 finding more room below, curled under and forward in its growth 

 and forms the fissure of Sylvius. I also noted that this crowding 

 backward of the frontal brain as it gresv larger affected the de- 

 velopment of the skull, and as the tendency of the animal to 

 assume more and more the erect posture balanced the head upon 

 the more perpendicular spinal column, that the spinal cord neces- 

 sarily assumed less obliquity of junction with the brain base, 

 until, in some men, the angle of the cerebrum and medulla ob- 

 longata is 90 degrees. At the same time, the forehead, by press- 

 ure of the brain from behind, had a tendency to become more 

 prominent. 



At a meeting of the Chicago Academy of Medicine, March 13, 

 1891, when a number of convict skulls were being examined, I 

 reminded the Fellows present of the publication mentioned, and 



stated that if this lessened obliquity of the medulla could be ac- 

 cepted as an index to the greater intelligence of animals, there 

 might also be an osseous adaptation of the occipital bone to the 

 angle formed by the medulla and brain. I therefore arranged the 

 skulls in a series from greater to less angularity of the basi-occipi- 

 tal or basilar process, and was assured by Drs. Lydston, Williams, 

 and Talbot, who were familiar with the histories of the individuals 

 whose skulls were thus arranged, that this estimation of their in- 

 telligence was a very good one. With a pardonable desire to 

 fully establisb my priority to this announce nent, I will mention 

 that there were present Drs. Lydston, Talbot, Moyer, Kiernan, 

 Stillman, Lagorio, Zeisler, Pynchon, and Williams at this March 

 13 1891, meeting. 



The exterior surface of the basilar process, unless compensated 

 by differences in diploe thicknesses or in some other way, should 

 give a corresponding inclination to the pharynx at the junction 

 of the basi-occipital with the body of the sphenoid, and as many 

 thousand observations would be needed to establish relationships 

 of this kind, I have concluded to ask laryngologists and others 

 who have occasion to frequently examine throits, to keep I'ecords 

 of pharyngeal appearances and other data, from which deductions 

 may be made, as follows : — • 



1. Inclination of posterior pharynx. 



First degree, approaching the obliquity found among quadru- 

 peds. 



Second degree, obliquity less than first and greater than 



Third degree, upright basilar process, or nearly so. 



For the present, at least, more divisions between perpendicu- 

 larity and the horizontal can scarcely be made in the living per- 

 son, owing to muscular, mucous, and other coverings varying in 

 thickness, enabling rough estimates only. A separate set of ob- 

 servations should be made upon skulls, where sufficient was known 

 of the history to form an estimate of intelligence, the base for 

 measui'ements being the same as with Camper's angles. 



3 Shape of skull — brachycephalic, dolichocephalic, meso- 

 cephalic. 



3. Size of skull, large, medium, or small for the age, height, or 

 sex. 



4. Intelligence. 



5. Education. 



6. Camper's angle. 



7. Other information not included above, as to disease or injury 

 affecting skull or brain, criminality, insanity, etc. 



The correlations should he accepted as inter-dependent and not 

 disconnected. For example, instead of intelligence being indicated 

 by a high, wide, bold forehead, there may be hydrocephalic 

 idiocy, and, generally speaking, we may sum up some cranio- 

 cerebral peculiarities thus : — 



1. The more erect position tends to move the foramen magnum 

 forward Increased intelligence and erectness are generally, but 

 not invariably, associated in animals, so the position of the fora- 

 men alone as an index has a restricted value. 



3. The frontal brain-growth is always associated with increased 

 intelligence, and this development crowds the sulcus of Rolando 

 farther back and pushes the medulla oblongata and pons Varolii 

 into a more and more upright position, provided the brain-growth 

 is greater than that of the skull, for a roomy skull may afford ex- 

 pansion and allow the primitive obliquity of medulla and occipital 

 bone to persist. 



3. The adjustment of the skull to its contents is a complex 

 matter, but may be better understood by relating cause and effect 

 as acting upon both more or less simultaneously, particularly with 

 regard to the differences in hardness and developmental changes 

 in both. For example, the beaver's skull and brain seem to have 

 kept pace together so as to render convolutions unnecessary, and 

 the beaver is an intelligent animal. The brain of Professor Leidy 

 was highly convoluted, and appears to have been rendered so by 

 his cerebral being greater than his skeletal growth, and this would 

 seem to have been a family peculiarity, for his brother's brain 

 presented a similar appearance of crowded convolutions. 



4. When a juvenile retreating forehead has gradually been re- 

 placed in an adult by a more perpendicular one, through educa- 

 tion acquired later in life, then the frontal brain may have qrowded 



