maximum extent with what is known as the Pueblo II 
expansion; and throughout the Southwest, after about 
A.D. 950, the archaeological maize shows a blending of 
Chapalote, teosinte and Maiz de Ocho. The persistence 
until at least A. D. 1247 of essentially pure Maiz de Ocho, 
along with other strongly Chapalote-affiliated maize, is 
dramatically shown at Painted Cave, northeastern Ari- 
zona (Haury, 1945, Plate 36). 
The reason for the Pueblo II expansion into areas not 
previously occupied by horticulturists has not been satis- 
factorily explained. A period of more favorable rainfall 
has generally been accepted as one factor. We are sug- 
gesting here that a more important factor was the intro- 
duction of the new race of maize, Maiz de Ocho, which, 
when blended with the previously cultivated maize, re- 
sulted in more abundant yields of a grain that was not 
only more easily milled, but also better suited to a wider 
range of environments, particularly higher elevations and 
latitudes. Thus, the introduction of Maiz de Ocho ap- 
pears to have provided a food resource that contributed 
to a population increase, and a maize sufficiently adapta- 
ble to higher latitudes that it permitted this increased 
population to carry the Pueblo farming way of life an 
additional 250 miles farther north than had previously 
been possible. Although the Pueblo area spread limited 
distances both east and west during this period (ca. A.D. 
900--1100), the most dramatic expansion was to the north, 
with the movement of the Fremont and Sevier (probably 
Plateau Shoshonean) peoples into the northern 85% of 
Utah (Gunnerson 1960, 1962). 
This study started with an examination of maize re- 
mains collected by the Claflin-Emerson Expeditions to 
eastern Utah sponsored by Peabody Museum of Harvard 
between 1928 and 1931. The archaeology of some of 
these sites has been described previously by Morss (19381) 
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