had its origin as a wild pod corn in the lowlands of South 
America. The origin of maize from pod corn is well estab- 
lished by the Bat Cave remains, but this does not prove 
that maize originated in South America. The fact that 
weak alleles of pod corn still have their highest frequency 
in South America may be of some significance in this 
connection. Also significant may be the fact that the 
earliest Bat Cave maize is glabrous and that there is a 
center of glabrous maize in the highlands of Bolivia, 
Peru and Ecuador. 
If an exact dating of the Bat Cave remains can be 
agreed upon, perhaps a correlation of the Bat Cave maize 
with prehistoric maize of the same period in South Amer- 
ica will throw new light on the problem. In the mean- 
time, the question of where maize originated as a wild 
plant is not answered by the new evidence. 
SUMMARY 
1. Remains of maize isolated from a cultura] deposit 
in Bat Cave in New Mexico reveal a distinct evolutionary 
sequence. 
2. The remains are conservatively estimated to repre- 
sent a span of approximately 8000 years, beginning not 
later than 2500 B.C. They may actually have begun 
much earlier. 
3. The maize excavated from the lower strata is the 
most primitive maize so far known. It is both a pod corn 
and a pop corn. The ear is not enclosed in husks, but is 
surrounded at its base by an involucre of leaf sheaths. 
4. This early maize is clearly not derived from teosinte. 
5. Beginning about midway in the sequence, there is 
strong evidence of an introgression of teosinte germ- 
plasm into maize. 
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