Welcome to Quantum Magazine's podcast.

Each episode, we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

Super genes that lock inherited traits together are widespread in nature.

They have both benefits and risks. And they're complex. That's next.

Quantum Magazine is an editorially independent online publication supported by the Simons Foundation to enhance public understanding of science.

Thousands of miles from home in the steamy Amazon rainforest in the mid-1800s,

British naturalist Henry Walter Bates had a problem.

More than one, really. There were thumb-sized

biting insects, the ever-present threat of malaria, venomous snakes, and mold and mildew that

threatened to overtake his precious specimens before they could be shipped back to England.

But the nagging scientific problem that bothered him involved butterflies. Bates had noticed

that some of the brightly colored heliconnius butterflies in the forest didn't flit about like the rest.

They moved more slowly. So he captured them and examined them under his makeshift microscope. That's when he

discovered that they weren't really heliconeous at all, but astonishing lookalikes from unrelated

families of butterflies. By the time Bates' discovery reached the scientific community in England,

Charles Darwin's then new

proposal of natural selection could explain why this brilliant mimicry occurred. Birds and other

predators avoid heliconia's butterflies because they're toxic to eat with a bitter taste. The mimics

weren't toxic, but because they looked so much

like the foul-tasting heliconnius, they were less likely to be eaten. The closer the resemblance,

the more potent the protection. What Bates and many later evolutionary biologists couldn't explain was how this mimicry was possible.

...