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Annals of Medical History 



is, from the geological standpoint, of rela- 

 tively recent origin and has afflicted the 

 inhabitants of the earth for only the last 

 one-quarter of the earth's history — that 

 is, for the last 25,000,000 out of a possible 



Fig. 13. The mandible of a cave bear, Ursus 

 spe xus, Pleistocene of Europe, showing the ravages 

 of disease. Caries and the absorption of alveolar 

 processes, as well as necrotic sinuses are evident 

 in this mandible. (After Mayer.) 



100,000,000 years. Future discoveries will 

 doubtless modify our present conceptions, 

 but the above outline is a summary of our 

 present knowledge of the rise and develop- 

 ment of disease among animals. 



TABULATION OF GEOLOGICAL EVIDENCES 



The table given below will show at a 

 glance the antiquity of pathological evi- 

 dences in geological history. The estimates 

 of time are based upon the relative thick- 

 ness of the pre-Cambrian and post-Cam- 

 brian rocks, after Walcott and Schuchert, 

 as given by Osborn in his "Origin and 

 Evolution of Life." ; ; The estimates of the 

 duration of the geological periods vary 

 greatly. The duration of the Proterozoic 

 was as great, probably, as all post-Cam- 

 brian time, which has been estimated as 

 high as 100,000,000 years. A study of radio- 

 active substances gives estimates as high 

 as 1,600,000,000 years for the duration of 

 the Archeozoic, although Walcott esti- 

 mates that only 70,000,000 years have 

 elapsed since the beginning of sedimenta- 

 tion. W hile authors vary greatly in their 

 estimates, they all agree that the duration of 

 geological time has been very great, run- 

 ning into many millions of years. The 



33 Osborn: "Origin and Evolution of Life," p. 153. 



estimates given in the first column of the 

 table are extremely conservative. I have 

 followed Osborn in this column. In the 

 second column a much greater estimate is 

 given. The table will show the relative 

 antiquity of various diseases, whatever 

 values are assigned to the time estimates. 



FOSSIL PATHOLOGICAL LESIONS 



The following annotated list and illustra- 

 tions of fossil lesions will indicate the extent 

 of diseases among fossil vertebrates. The 

 study of these lesions is by no means com- 

 plete, and other pathological processes will 

 doubtless be indicated as the study of them 

 progresses. 



1. Caries is very common among fossil 

 vertebrates and has been described by 

 Renault as occurring among Permian fishes, 

 20,000,000 years ago. A large marine reptile, 

 from Belgium, one of the Cretaceous mosa- 

 saurs, according to Abel, shows in the left 

 mandibular ramus extensive evidences of 

 the ravages of this disease. In an early 

 Tertiary species of the three-toed horse 

 (Fig. 8), the mandible has been affected 

 by caries and possibly also by actinomycosis, 

 as well as some necrotic process which lias 

 resulted in the exposure of the roots of the 

 teeth and the absorption of the alveolar 

 margins, similar to the results of pyorrhea 

 alveolaris. Caries has been noted also in the 

 tooth of a mastodon, and in the early cave 

 bears (Fig. 13) of Europe. The early races 

 of men were singularly free from this disease 

 as evidenced by the fossil remains. 



2. Pyorrhea Alveolaris, or some sim- 

 ilar pathologic process, is especially evident 

 in the absorbed alveolar margins and in the 

 loosened teeth of a three-toed horse (Fig. 8) 

 from the Miocene of North America. It is 

 also extensively indicated in the mandibles 

 of the European cave bears (Fig. 13), and 

 in a Cretaceous mosasaur from France. 



3. Deforming Arthritides are fairly 

 common among fossil vertebrates and indi- 

 cate a variety of pathologic conditions. 



