Mutation!

Today we went over the anatomy of the dragonflies torn apart last week and then examined various preserved beetles, discussing how dragonflies, like all insects, share certain common body traits. This moves us into our new unit: mutation!

Mutations are behind all the diversity of life. For more on the subject, the first episode of the currently airing Cosmos show goes into the evolution of the eye, a long and complex process.

Some other examples of mutation:
Corn, before and after human selection pressures:

Moths, before and after smog painted their habitat black:

Which would you eat first?

It's important to remember that mutations are rarely "good" or "bad". A moth mutated to have black pigment in an environment full of white things would be "bad", but if the environment changed to be full of black things, the mutation would be "good". Corn is now crippled, requiring humans to pollinate it rather than the wind and humans to separate and plant the kernels. But it's also one of the most common plants on the planet.

Two interesting side facts:

1) You may notice the black moth is not camouflaged as well on the dark surface as the white moth on the light. This is because the black is the result of a single mutation to make it solidly black. The fancy dimpling of the original moth is the result of thousands of years of chance mutation until the right combination was found. For the black moth to gain similar patterns would take thousands more years.

2) It doesn't look like they'll have thousands more years to perfect the black look. The original peppered moth has returned to most of its territory now that we have rules against factories belching endless smog, and it's thought the black moth will disappear again completely within a few more years.

But for an example of what uninterrupted mutation chains can do, enjoy this Phalera bucephala moth!

It's also known as the buff-tip moth.

Finally, the human hairball (or bezoar)! Because humans don't eat hair as quickly or as often as animals like cats, we also don't quickly vomit it all over your carpet. Left alone, bezoars will end up worn down by the acid into a tight ball. Removed before then, they're a hairy mass.

People in the past believed they cured poisoning, possibly just because they figured something so bizarre had to have some practical use. Bezoars do not cure poisoning, call Poison Control if you're poisoned instead!