The result of the efforts of our corn breeders is reflected in the slide below. You can see the improvement in average corn yields is also accelerating at an amazing pace.
When smart folks like the founder of Pioneer Hi-Bred, Henry Wallace, began breeding hybrid corn in the 1930's they were starting from scratch. It was like baking a cake with no recipe, but they did make progress by developing inbred parents which made better hybrids. This was an amazing discovery for its time.
Wrong. Smart forward looking people recognize the need to take a look over their shoulder once in a while.
Pioneer has kept a seed bank of every inbred developed by their corn breeders since Henry Wallace's time. Now, thanks to technology, researchers have catalogued every gene on every chromosome of this genetic library. They can go back and pluck useful genes from 75 years ago and incorporate them into today's hybrids. They do this with things like gene markers and molecular genetics which I will not understand no matter how many times it gets explained to me.
This is a shot depicting the modern hybrid, 38N88, within Pioneer's library of genetics. Each coloured spot represents an inbred parent. The male parents are pink and the female parents are blue. Gene jockeys are weird, I was brought up to think boys are blue. The pedigree of 38N88 stretches back to Henry Wallace's time. The specific genes that make 38N88 successful as a hybrid are all catalogued.