Maiz de Ocho germplasm predominates. Here in the 
Chacuaco Canyon area, Chapalote was reduced to only 
two percent while Maiz de Ocho occurred at 22.8 per- 
cent, Maiz de Ocho Mix at 36.9 percent and the inter- 
mediate hybrid type (Pima Papago) at 386.3 percent from 
a total of 201 cobs (Galinat and Campbell, 1967). As 
the distribution progressed onto the Plains and north- 
eastward, the frequency of pure Maiz de Ocho increased. 
Nevertheless, even the northern flints may exhibit some 
degree of Chapalote germplasm derived from their an- 
cestral mixing in the Southwest such as is manifest by 
the flinty kernels or the occasional kernel row numbers 
of over eight. 
SUMMARY 
The radiocarbon date of 18188 B.C. is the earliest 
North American date yet reported for the introduced 
race of maize, Maiz de Ocho, or its hybrid, Pima Papago, 
involving the indigenous race, Chapalote. The early date 
comes from the BR-45 Site about 124 miles to the west 
and 1000 feet higher than the Albuquerque area of the 
Middle Rio Grande Valley, New Mexico. Older remains 
of the original pure form of Maiz de Ocho probably will 
be discovered in Chihuahua and Sonora, perhaps near 
the valleys draining to the west coast of Mexico. From 
there, it is presumed to trace to South America where 
it has botanical affinities with the Colombian race, Ca- 
buya (Roberts et al., 1957). The early presence of the 
hybrid Pima Papago in New Mexico rather than the 
pure Maiz de Ocho parent can be attributed to an in- 
creased adaptability, vigor and productivity associated 
with outcrossing to the indigenous race, Chapalote. The 
eight-rowed parent remains in a semi-hybrid condition 
in the form of Harinoso de Ocho in northwestern Mexico 
(Wellhausen et al., 1952), while it has assorted out to an 
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