The evolution of Corn
Thousands of years ago, farmers discovered teosinte with soft-shelled seeds, six to a dozen per set, that were good to eat. They started replanting this teosinte and over many years, added varieties with more than one row of seeds.
Today, the great, great grandchild of this Mexican grass can have cobs 30 centimeters long, each carrying more than 500 seeds. It is corn, one of the most important crops in the world.
Our modern understanding of how traits may be inherited comes from three principles of inheritance proposed by Gregor Mendel in 1865:
- that inheritance of each trait is determined by "units" that are passed on to descendants unchanged (now called genes)
- that an individual inherits one such unit from each parent for each trait
- that a trait may not show up in an individual but can still be passed on to the next generation.