A Little Bit More
Today’s corn (called maize in many parts of the world) is a far cry from what the settlers found when they arrived in North America, and that corn was much different from its ancestral plant. In domestication, corn has lost its ability to reseed itself and is now totally dependent upon humans to keep it (domestic corn) from becoming extinct. Selective breeding has placed value on an ear that retains its tightly packed kernels; the seeds germinate well enough but the tightly-packed seeds don’t scatter and any seedlings that sprout simply choke one another out.
It’s interesting that the origins of something as common as corn should prove so difficult to understand. Scientists have debated, sometimes quite angrily, for years over the origins of corn and it has taken sophisticated genetic testing - DNA fingerprinting - to help us get the facts. The latest word in 2004 is that corn’s ancestry is a serendipitous combination of two grasses, Teosinte and Gammagrass.
It is also believed that this artificial combination quickly led to further changes and within as little as 100 years, may have resulted in an ancestoral corn plant that’s not too different than what we see today.
Then, after learning to plant and nurture this Teosinte/Gammagrass hybrid, early farmers kept on selecting better and better mutants. With each harvest, they chose the next crop's seeds from plants that were the most productive, easiest to thresh and hardiest.
Scientists working on the origins of corn point out that understanding the genetic origins of this plant will help us today as we seek to produce new strains of drought- and pest-resistant corn to meet the demands of a hungry world.
Activities
Corny Law of Averages
Objectives: Mathematic calculations that make sense
Materials: Corn on the cob, pencil and paper
You should be able to find some ears of dried corn in the fall that are destined for decorations. These will make good material for the students to use to apply some mathematical skills.
1. Ask your students if they think the number of rows of kernals on an ear of corn is the same on each and every ear (you may not be sure yourself!).
2. Pass out the corn cobs and have students count the number of rows on “their” ear.
3. Have the students report back what they found and place the number or numbers on the board.
4. If the number of rows vary, have your students average the number of rows for those that were brought in to class.
5. Now ask your students whether they think the number of kernals on each row is the same or not. Have students count the kernals on two rows of “their” ear to see how many there are.
6. Again, place the two numbers (if they differ) each student counted on the blackboard and again have them find the average number of kernals per row.
7. Now ask your students whether they think the number of kernals on the entire cob is the same or not. Have students count ALL the kernals on “their” ear to see how many there are.
8. Place the number of kernals on an ear on the board and have the students find the average number according to the ears in their class sample.
As long as you have the corn, it may be fun to plant the kernals and see what sprouts. I’m uncertain if the kernals need to be stratified (dormant at low temperature) so you may need to place them in your refrigerator (or leave them outside) for 8-10 weeks before planting. Once you do plant the corn kernels, you can grow them right indoors (full sun) and watch them develop.
Key Concepts
Food Webs /Food Pyramids, Identification
Questions
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