Feeding more people
Breeders do not select at random. Each programme aims at a particular characteristic, and the characteristics chosen say a good deal about what a country needs.
What is selected for
Higher yield
More grain per plant, more milk per animal, more fruit per tree — the same land feeding more people.
Disease resistance
Varieties that survive an infection which destroys the crop around them. This is often worth more than yield, because a lost harvest yields nothing at all.
Shorter growing season
A rice variety that matures faster can give two or three harvests a year from the same field instead of one.
Tolerance of hard conditions
Varieties that will still crop in drought, in salty soil, or where water is unreliable.
Why it matters now
The world's population keeps growing while the area of farmland does not. The only way for a fixed area of land to feed more people is for what grows on it to produce more — which means improving the plants and animals themselves.
Improvement never finishes
A variety bred to resist a disease works until the organism causing that disease changes — and it changes by mutation, exactly as described earlier in this chapter. Breeders are therefore never done; they are keeping pace with something that is also evolving.
Yield, resistance, speed, tolerance
Crops and livestock are improved by selecting for higher yield, resistance to disease, faster maturity and tolerance of hard conditions — all of them inherited characteristics.