General Aztecs Maya Tocuaro Kids Contact 18 Oct 2018/12 Deer
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Article suitable for older students

Professor Michael Heinrich

Question for October 2018

With the (different natural) colours of maize, does it depend on where they’re grown or what season it is? Asked by Green Park School. Chosen and answered by Professor Michael Heinrich.

Pic 1: Photograph of Barbara McClintock’s ears of corn and a microscope
Pic 1: Photograph of Barbara McClintock’s ears of corn and a microscope (Click on image to enlarge)

The story of maize or corn brings together many disciplines, an attention this important crop most certainly deserves. In 1983 and more than 30 years after her initial discoveries the botanist Barbara McClintock (1902 - 1992) received the Nobel Prize in Physiology or Medicine for discovering “mobile genetic elements” and for this studies in maize (Zea mays L.) were essential. Early in her career (in the 1930s) she developed methods to visualize and characterize maize chromosomes.

Pic 2: McClintock giving her Nobel Lecture in Stockholm
Pic 2: McClintock giving her Nobel Lecture in Stockholm (Click on image to enlarge)

And this then answer the questions: Some of these genes code for the colours of maize. Very important in this context are her systematic studies on mosaic colour patterns of the seeds, and specifically the genetic mechanisms inheritance. This was called jumping genes and later transposons. Later in her career Barbara McClintock also looked at the origin of maize and the genetic differences between the varieties and cultivars* of maize.

Pic 3: Centéotl, Aztec god of maize
Pic 3: Centéotl, Aztec god of maize (Click on image to enlarge)

Let’s go back to México: In Nahuatl cintli means “dried maize still on the cob” and elote means a corncob – so the language is rich in names for what we just call maize or corn. And they even had a god – Centeōtl, who is the son of the earth goddess Tlazolteotl and of the planet Mercury Piltzintecuhtli. Centeōtl was one of the most important gods of the Aztecs and of course his head was adorned with maize. All this tells us how important maize was to the Aztecs and they developed (bred) many cultivars also differing in their colour.

Pic 4: The husked ears of three maize cultivars*
Pic 4: The husked ears of three maize cultivars* (Click on image to enlarge)

So, no it does not depend on where it is grown, but the colour tells us a lot about genetics and the ingenuity of the Aztecs in breeding new varieties of maize.

* A ‘cultivar’ means a variety cultivated by selective breeding.

Picture sources:-
• Pix 1 & 2: photos from Wikipedia (Barbara McClintock)
• Pic 3: Illustration by and courtesy of Gwendal Uguen
• Pic 4: photo from Wikipedia (List of sweetcorn varieties).

‘Why did the Aztecs worship maize?’

Professor Michael Heinrich has answered just this one question

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