2 
SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 146 
there such a noticeable difference in the physical and cultural patterns 
of the two areas ? 
A climatic barrier can be traced along the line of the Tropic of 
Cancer. The area north of this line was, for the most part, ignored by 
the sedentary valley peoples. Recently, the Aftosa Commission used 
this same climatic boundary as a determinant between the southern 
area of hoof and mouth disease contamination and the uncontam- 
inated north. 
Anthropologists have not thought of this area as the hearth of any 
great culture. It has been portrayed as that area through which the 
higher cultures of Mesoamerica traveled while making contact with 
the North American southeast and southwest. In both time and space 
it is thought of as the homeland of primitive groups, who on occasion 
were inspired by certain valley cultures, late in their historical con- 
tinuums, particularly in both coastal zones. At best it has been con- 
sidered as peripheral to the culture of both Mesoamerica and the 
North American southwest. 
Swadesh (1959) recognizes two major language groups of consid- 
erable time depth in northern Mexico. Throughout the western portion 
of the Chichemec country, as well as in Tamaulipas, he notes the pres- 
ence of the old Macro-Nawan group. Scattered islands of the Macro- 
Yuman group are charted in Coahuila as well as along the Sonoran 
coastal plains and in upper Baja California. Taylor (1961, pp. 71-81) 
suggested that this latter group may be a linguistic remnant of a very 
old Yuma desert cultural pattern that once covered the entire north- 
ern zone. A third block of languages, located in the central plains, 
may be part of a late Athapascan infiltration, as it includes such 
languages as the Toboso tongue. 
The following description of the historical continuum is framed in 
terms of a series of events which may have had trigger effects upon 
the inhabitants in the archeological zone. Unfortunately, the lack of 
detailed studies does not permit one to speculate on causal factors. 
One can only offer suggestions based on scant evidence and com- 
parative factors drawn from the surrounding cultural areas. The pro- 
posed historical outline is by no means definitive, but perhaps it will 
be stimulating. 
MAN AS A SOIL MEMBER 
THE PRECERAMIC HUNTERS AND GATHERERS OF PLEISTOCENE FAUNA 
AND FLORA 
Throughout the length and breadth of northern Mexico have come 
bits of evidence indicating that man once roamed the area in the 
