l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



parasite data may be applied to a great range of problems. This, 

 which we might well name the von Ihcring method, gives decisive 

 results in many cases, while in other instances it furnishes merely 

 corroborative evidence or evidence to be joined with that from other 

 sources. 



Metcalf subsequently published several papers discussing the host- 

 parasite method or host-parasite data, as noted in the appended 

 bibliography. 



Darling (1921, 1925) used data from the hookworms of man to 

 indicate human origins and migrations. Before the publication of this 

 earlier paper Darling had very likely not read the papers of von 

 Ihering, Kellogg, Harrison, Johnston and Metcalf, which had made 

 somewhat similar use of parasite data, for he does not refer to these 

 authors. It seems probable, therefore, that Darling may have been 

 another independent discoverer of the broad significance of such data 

 from parasites. The following quotation will show Darling's sug- 

 gestions : 



.... man of the Holartic regions [is] parasitized exclusively or almost ex- 

 clusively by Ancylostoina duodenalc, while man of the Oriental and Ethiopian 

 regions [is] parasitized exclusively or almost exclusively by Nccator americanus. 

 This .... suggests the possibility of ... . there having been two primitive 

 races of man, each one originally parasitized by a particular species of worm. 

 Certain it is that N. americanus is found more exclusively among' black and 

 brown-skinned races, while A. duodouilc is found exclusively or greatly pre- 

 dominates at the present time among Caucasian and Mongoloid stocks. 



It may be that a Eurasiatic race of men, possibly the Pithecanthropus of 

 Trinil, Java, became split off and furnished the stock from which man of oriental 

 and Ethiopian regions sprung. Proliopithecus emerging from Holarctic Africa 

 may have been not only the parent form of man, gibbon, chimpanzee, gorilla 

 and the orang-outang, but he may have harbored the parent form from which 

 have arisen the different hookworm species found in the various species of 

 anthropoids of today. Possibly the ancestral tree of the primates can be revised 

 after a study of the host relationships of their respective obligate nematode 

 parasites. At any rate we can say that it seems likely from the present distribu- 

 tion of A. duodenalc and A'^. americanus as determined in surveys recently made 

 of selected groups that there were originally races of man parasitized exclusively 

 by A. duodenalc and inhabiting the Holarctic region, that is Europe, Asia, north 

 of the Oriental region, and northern Africa ; and that there were other races 

 of man parasitized exclusively by N. americanus and inhabiting the Oriental 

 region, that is the southern peninsulas of Asia and Indoasia or the Malay Archi- 

 pelago ; and also the Ethiopian region, that is, Africa south of the Sahara 

 Desert. 



Ewing (1924) in a study of biting lice of the family Gyropidae 

 discusses the significance of their geographical and host distribution 

 arguing in favor of a crossing over between rodent hosts and primate 



