The history of Maize domestication
A Brief Prehistory of Mexico
Time before the
present b.p.
Mirambell
(2000)
Zeitlin y Zeitlin
(2000)
4,000 - Neolítico Form...
Early microfossil
evidence for
maize in
archaeological
contexts.
Sites of the Protoneolithic period
Archaeological
context of the
Protoneolithic
Period
(1)
Archaeological
context of the
Protoneolithic
Period
(2)
Figures from Ranere et al, 2009
Morphological Characters
studied on archaeological maize
1. Specimen Condition
2. Specimen Length
3. Cob Diameter
4. Rachi...
San MarcosCoxcatlanEl Riego
Calculating evolutionary rates
• Calculation of rates of change follows Haldane
(1949):
Darwin = ln(x2) - ln(x1) / t
Where...
San MarcosCoxcatlanEl Riego
Evolutionary rates in Wheat
(after Tano and Willcox 2006)
Postulated allele frequencies of indehiscent (d) and dehiscent (...
Conclusions
• The antiquity of human manipulation of maize is suggested
by maize and teosinte microfossils in some areas o...
The history of maize march 2009 final
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The history of maize march 2009 final

  1. 1. The history of Maize domestication
  2. 2. A Brief Prehistory of Mexico Time before the present b.p. Mirambell (2000) Zeitlin y Zeitlin (2000) 4,000 - Neolítico Formative 5,000 - 4,000 Protoneolítico Late Archaic 7,000 - 5,000 Protoneolítico Middle Archaic 12,000 - 7,000 Cenolítico superior Early Archaic 35,000-12,000 Cenolítico inferior Late Paleo-Indian ? to 35,000 Arqueolítico Early Paleo-Indian 2,000
  3. 3. Early microfossil evidence for maize in archaeological contexts.
  4. 4. Sites of the Protoneolithic period
  5. 5. Archaeological context of the Protoneolithic Period (1)
  6. 6. Archaeological context of the Protoneolithic Period (2) Figures from Ranere et al, 2009
  7. 7. Morphological Characters studied on archaeological maize 1. Specimen Condition 2. Specimen Length 3. Cob Diameter 4. Rachis Diameter* 5. Pith Diameter* 6. Row Number* 7. Cupule Width* 8. Cupule Depth 9. Rachid Length* * Show significant variation over time
  8. 8. San MarcosCoxcatlanEl Riego
  9. 9. Calculating evolutionary rates • Calculation of rates of change follows Haldane (1949): Darwin = ln(x2) - ln(x1) / t Where ln is the logarithm base e, x1 and x2 are the later and earlier average specimen dimension and t is the length of time separating the two specimens.
  10. 10. San MarcosCoxcatlanEl Riego
  11. 11. Evolutionary rates in Wheat (after Tano and Willcox 2006) Postulated allele frequencies of indehiscent (d) and dehiscent (D) over 10000 + radiocarbon years of Middle Eastern prehistory (left) and relative fitness of geno- types of wild wheat. While selection for indehiscent phenotypes appears to have Occurred gradually, selection is not continuously increasing. This is similar to the puntuated pace of evolutionary change in maize in Mesoamerica
  12. 12. Conclusions • The antiquity of human manipulation of maize is suggested by maize and teosinte microfossils in some areas of the Americas, this evidence does not yet indicate the impact of human selection on maize. • Contemporaneous Protoneolithic sites in Mesoamerica are discordant about time and place of domestication. • Study of inflorescence morphology shows the intensity of human selection on maize is greatest around the 5th millenium BP cal. • Human selection intensity on maize is not continuous, in a similar way to that of the Middle East where local effects – environmental variation between and within sites over time – affect the cultivator’s ability to monitor and act on the effects of selection.

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