Nobody designs these creatures. Hawks eat whichever ones they happen to spot, the rest have offspring that are almost but not quite copies of their parents. Within a few dozen generations the population matches its background.
The creatures start out mostly mid-toned on pale sand. Watch the colour histogram slide toward the sand marker, then press Change the environment.
Each creature has two inherited traits: its shade, from near black to pale cream, and how fast it can run. Hawks wander the ground. Every moment a hawk glances at one creature in range and notices it with a chance that grows with how much it stands out from the ground. A noticed creature runs; if the hawk closes in before it tires, it eats.
At the end of each generation the survivors breed back to 100. Each baby copies one parent's traits with a small random error. Running fast burns energy, so faster creatures raise fewer young. Nothing else is programmed.
No creature changes during its life and none is trying to adapt. Random copying errors have no direction at all. Direction appears only because the hawks remove some variants more often than others, and that bias, repeated every generation, builds something that looks designed.
This happened in real moths. Dark peppered moths were first recorded near Manchester in 1848 and made up about 98% of the local population by 1895 as soot blackened the trees. After clean-air laws they became rare again.
Anything that copies itself with variation, under pressure, evolves. That includes the germs and pests we fight, and the molecules and designs we deliberately breed.
An antibiotic is a very efficient predator. The few bacteria that happen to resist it survive and multiply. Alexander Fleming warned of this in his 1945 Nobel lecture. A 2022 study in The Lancet estimated that resistant bacterial infections directly caused 1.27 million deaths in 2019.
In the demo: raise predation pressure and the population shifts faster.More than 500 insect and mite species have evolved resistance to at least one pesticide. Farmers growing insect-resistant Bt crops are required to plant "refuges" of ordinary crops, so susceptible insects survive to breed with resistant ones and slow the spread.
In the demo: survivors are the parents; remove the variation they rely on and adaptation stalls.Frances Arnold won the 2018 Nobel Prize in Chemistry for breeding enzymes the way farmers breed crops: mutate the gene, test thousands of variants, keep the best, repeat. Evolved enzymes now make drugs and work in cold-wash laundry detergents.
In the demo: mutation plus a selection rule, run over and over.Genetic algorithms apply the same loop to designs inside a computer. NASA's Space Technology 5 satellites, launched in 2006, carried an antenna whose odd bent-wire shape was evolved by software rather than drawn by an engineer. It was the first evolved hardware flown in space.
In the demo: the histograms are a population searching for a good answer.A tumour is a population of varied cells. Full-dose chemotherapy can kill the sensitive ones and leave resistant ones with no competition. "Adaptive therapy" trials dose more gently on purpose, keeping sensitive cells around to hold the resistant ones in check.
In the demo: heavy predation with low variation leaves a population that is hard to shift back.During Mozambique's civil war, ivory poachers killed most of the elephants in Gorongosa National Park. Tuskless females were more likely to be spared. A 2021 study found that about 18% of females were tuskless before the war, but about half of the females who survived it were. Heavy fishing has likewise pushed some fish to mature younger and smaller.
In the demo: the hawks are the hunters; whatever they find easiest, they remove.