Human skeletal pathology in pre-Columbian populations of Chile • 149 



ALTERATION OF THE ENDOCRANIAL RETURN CIRCULA- 

 TION. The swimming stroke used in the coastal region cons- 

 ists of maintaining only the head outside the water. In con- 

 trast, hunting and food collecting on land tends to direct the 

 eyes and head downward. These head positions induce a 

 hyperextension and hypertlexion of the occipitoatloidal joint 

 as shown by the frequency of the third condyle and the de- 

 generative changes in the joint surfaces of ail of them. I think 

 that these sustained and frequent movements must have hin- 

 dered in a mechanical way the intracranial return circulation 

 at the level of vessels and plexus surrounding the foramen 

 magnum. It is also possible that, during the first years of life, 

 an internal cause has been added: brain edema. This condi- 

 tion might be caused by the increase of intracranial pressure 

 due to fluid retention produced by the ingestion of brackish 

 water. This would alter the return circulation, as shown by 

 the alteration of the course of the superior longitudinal sinus 

 (formation of an endobregmatic lagoon or cistern), which 

 would be a more apparent sign (see Table 2). 



ALTERATION OF THE BLOOD CALCIUM LEVEL. Sudden de- 

 compression during diving and perhaps the ingestion of food 

 rich in calcium may have raised the level of this element in 

 the blood. For mechanical reasons, calcium should tend to 

 concentrate in the blood stasis zones of the brain and produce 

 extravasation of the emissary vessels in the passing zones, 

 specifically in the ectocranial surface surrounding them on 

 their way out. This might explain the bone neoformation 

 described for the obeliac region and even the osteoma of the 

 auditory meatus. 



THICKNESS INCREASE OF CRANIAL BONES. A bone reaction 

 pattern which led to a thickness increase in the bones was 

 posed a long time ago for pre-Columbian populations in the 

 arid coast of northern Chile, without an explanation for its 

 causes (Vergara-Flores 1894, 1905; Fonck 1906). Findings in 

 this population confirm its presence, but its frequency and 

 intensity are lower than those established for a great number 

 of populations in America (Munizaga 1984:40). 



Various causes have been given to explain this bone reac- 

 tion pattern: diet, such as vitamin C (Bourne 1956) and D 

 deficit, hypervitaminosis A (Fonck 1906); anemia (Angel 

 1967; Munizaga 1965); and inheritance (Weidenreich 1943). 

 In this case, while an exaggerated thickness in reinforcement 

 zones is likely to be explained from a genetic point of view, 

 the increased thickness of the vault bones may also be due to 

 the first two already mentioned causes. It must be pointed out 

 that we have not found the orbital and parietal sieve plates 

 characterizing porotic hyperostosis. It might be that its ap- 

 pearance was modified by the alterations of the endocranial 

 return circulation appearing in this population in infancy. The 

 sole case we have found of sieve plates in their active phase is 



Table 3. Sex and age distribution on basis 

 of skulls 



Group I 

 Ages Infants Males Females Total 



NOTE: AO, vault sutures open, basilar 

 closed; Al, outer open, inner in closing 

 process; A2, outer and inner in closing 

 process; A3, outer and inner in advanced 

 closing process. 



similar to the one described by Ortner and Putschar 

 ( 1 98 1 :275 , Figure 4 1 7 ) as an example of rickets. In this case, 

 it would be difficult to accept the presence of such a patholog- 

 ic condition. 



Health relations to ecological balance 



The results of the examination of bones belonging to these 

 populations are surprising for two reasons: ( 1 ) low frequency 

 of cases of massive infection, of disabled individuals or ones 

 with advanced joint deterioration, as these frequently occur 

 in pre-Columbian to agricultural populations; and (2) ab- 

 sence of old individuals and high mortality of women in early 

 adulthood (see Table 3). Perhaps these human skeletal re- 

 mains were collected in a selective manner, as has been 

 shown to occur in other collections (Stewart 1969:444), or 

 selective loss of skeletal remains of one age group occurred, 

 such as when these are left on the surface (as we confirmed in 

 a neighboring field, where the loss of children's bones was 

 four times higher than that of adults' bones; Munizaga 

 1980:206). Llagostera (pers. comm.) has also obscr\'cd im- 

 portant variations in age classes in pre-Columbian cemeteries 

 of this zone. 



In spite of the possibilities analyzed, which might explain 

 this demographic distribution, 1 am inclined to think that 

 these populations are in balance and any normal or abnormal 

 alteration hindering the integration of an individual may be 

 the cause of his removal from the system. This would also 

 occur with pregnancy and might explain the mortality of 



Zagreb Paleopathology Symp. I98S 



