PRESKXT PR0IU.I:MS IX EVOLUTIOX AXD IIKREDITV. o^l 



Many of tin' cast's of ai'iested closure of facial sutures arc icver- 

 sioual, as they coriespond with tlic adult condition of other laccs, such 

 as the divi(h'd malar, or as -laponicuni. Tlu^ human i)rcma.\illary, a 

 discovery with which Goethe's name will always he associated, is sonu*- 

 tinies partially, more rarely wholly, isolated; it is late to unite with the 

 maxillary in the Australians, and has been rei)orted eidirely separate 

 in a new Caledoiuau cliild (Deslongchamps) and in two (ireenlamleis 

 (Cams). The orbito -maxillary frontal suture, cited by Turner as a re- 

 version to the pithecoid condition, is believed by Thomson, a tier the 

 examination of 1,037 skulls, to he merely an accidental variation, with- 

 out any deeper significance,* The development of the temporal bone 

 from two centers, observed by ]\reckel, (iruber, and many others, is 

 consick'red by Albrecht a reversu)n to the s<^[)arate quadrate of the 

 sauro-niamnialia. This 1 think is in the highest degree improbable (see 

 "Limits of Reversion"). The open cranial and closed facial sutures 

 are apparently associated with our increasing brain action anddecreas. 

 iug jaw action; in one case the growth is prolonged and the sutures are 

 left open, in the other, the growth is arrested and the sutures are 

 ch)sed. 



Is tlie lower jaw developing or degenerating? This (piesfion has re- 

 cently been the subject of a spirited controvei-sy between Mv. W. IMatt 

 Ball,t representing the Weisman school, and Mr. F. ] Toward Collins, | 

 .sui)porting Herbert Spencer's view that a diminishing jaw is one of the 

 features of our evolution which can only be explained by disuse. Mr. 

 C<>llins find that, relatively to the skull, the mass of the recent English 

 jaw is one-ninth less than that of the ancient British and, roughly 

 speaking, half that of the Australian. Fie appears to establish the 

 view that the jaw is diminishing. 



Closely connected with this is the evolution of tiie leelh; how are 

 they tending'? 



Flower§ has shown, as regards the length of our molar series, that 

 we, together with the ancient Uritish and l']gyptiaiis, belong to a small 

 toothed or '-microdont" race; the Chinese, Indians (Noi'tli American), 

 Malayans, and negroes in part, are intermediat(M)r " mesodont," while 

 the Andamanese, Melanasiaiis, Australians, and Tasmanians are ''ma 

 (;rodont." While undcrsize marks the molars as a whole, the wisdom 

 tooth is certainly in process of elimination; it has the symi)toms of de- 

 cline; it is very variable in size, form, and in the date of its api)ear- 

 nnce, is often misplaced, and is not uncommonl.\' (piite rudinuMitary 

 (Tomes). I Here is another instance where the knife and-forkless races 

 reverse our degeneracy, for in them not only is the last normal mnlai' 



"Journal <>/ Aiudomy and I'lii/siolof/y, 1890, ]). 348. 

 t Arc the Efi'ect.s of l's<^ and Disiisr Inhi-rited? Xatiu-e Series,. 1800, 

 t Tlio Lower .Jaw in ('ivilizo<l Racos, 18!tl. 

 '^Jonrnal of the Antli7-o})olo<jical Inflifnic, 1880, 

 Jl Dental Analonii/, j). IIH. 

 II. Mis. lil L'l 



