The Peppered Moth

Arising from our ashen pit of toil,

As forge and mill did shape this unkempt land;

The blackness of the trees from coal and oil,

Contrasted with the skin nature had planned.

A single, fragile pearl encased in jet,

Your pallor marked you out for all to see;

In contrast to our progress, blood and sweat,

Your population had no industry.

And then from deep within you came a switch,

We came across your shadow in the sky;

Your alabaster pelt had turned to pitch,

Forced to adapt so that you would not die.

I wonder if we ever get it right,

Will you turn back from darkness into light?

This is a Shakespearian Sonnet, based on recent research which has identified and dated the mutation which gave rise to the black form of the peppered moth in the UK, during the Industrial Revolution. Prior to this the peppered moths had a lighter form, but this made them stand out against the sooty bark on urban trees, making them an easy target for predators such as birds and bats. After a dip in their population, the peppered moth was observed again, but with a black colouring; the first documented recording of such a moth coming in Manchester in 1848.

The researchers in this study have found that a ‘jumping gene’ was responsible for this genetic mutation, which is often given as a classroom example of a visible evolutionary response. Using statistical modelling, the researchers have dated this mutation to around 1819, which indicates that after their numbers dwindled it took approximately 30 years for the genetically modified variety to become popular enough again to notice.

You can find out more about the Peppered Moth, including a number of resources for schools, here.

An audio version of the poem can be heard here.