cestor occur today; types of Tripsacum and corn which 
come extremely near to satisfying the requirements for 
the putative parents of teosinte are well known. Yet 
Weatherwax (41,42) states that it is the tripartite theory, 
rather than the “‘simple’’ theory of common ancestry, 
which ‘‘is topheavy with assumptions of such character 
that if one of them should be rejected the whole struc- 
ture would fall.”’ 
The theory of common ancestry has two additional 
weaknesses which are serious: (A) It does not, Weather- 
wax’s and Randolph’s contentions to the contrary, not- 
withstanding, explain all of the known facts. (B) It can 
not easily be tested. 
A. Some of the facts which the theory of common 
ancestry does not explain are discussed in detail in other 
papers of this series (28, 32). Here it will suffice to point 
out that the theory does not account for the facts that 
(a) teosinte is intermediate between maize and Tripsacum 
in a great majority of its characteristics (21, 31); (b) 
early archaeological maize is more ‘‘maize-like’’ than 
later maize (7, 11, 19, 20, 25); (c) fossil pollen of maize 
and Tripsacum were found at great depths at one site in 
Mexico, whereas teosinte pollen occurred only in the 
upper levels of the drill core; (d) forms of pod corn are 
now in existence which possess all of the characteristics 
expected in the ancestral form (16, 17); (e) variation in 
knob numbers is correlated with tripsacoid characteristics 
(18), and with proximity to Guatemala, the reputed 
center of origin of teosinte (21, 80). 
B. The theory is largely untestable, because the only 
evidence which could prove it to be correct beyond a 
reasonable doubt would be the discovery of prehistoric 
remains, antedating agriculture, of all three groups of 
the American Maydeae and of the remote ancestor from 
which these three groups stem. Since it is largely untest- 
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