Unnatural Selection: Part One

Natural selection is the key mechanism in evolution. It is the ‘selection’ of desirable traits that allow for plants and animals to best adapt to their surroundings. However as time progresses there surroundings appear to be mostly of a human creation. As mother nature steps aside and we humans begin to shape the world, these plants and animals must adapt to living with us, rather the slower natural change of nature.

This is a process we can call ‘unnatural selection’. I suppose you can make the argument that humans are part of nature and as such cause natural change, but the global influence we have is nothing like anything else found in nature. Humans are very odd.

We collect in huge megalopolises, working for paper, then trading paper for food and stuff. So much stuff. Mountains of stuff. We burn fossils found deep in the Earth’s surface so we can travel to get more paper. Which means more food and, most exciting of all, more stuff. . We don’t live ‘in nature’, we organise and shape nature. We like symmetry and order (look at the garden of the average home for example). We destroy thousands of hectares of forests, destroy thousands of habitats and drive to extinction an array of plants and animals. But what do we put in its stead? Probably corn. We like corn. Then we use pesticides to fight off the ensuing resistance by nature against this incredibly unnatural process (called crop monocultures). It’s completely backwards. But we do get a lot of corn. And more corn usually means more stuff. We shape the ecosystems of the world and therefore also the creatures of world as well. For centuries the battle between mother nature and humans has raged, and it seems humans are beginning to win.

The Peppered Moth.png

Let’s start small. So this is not about how we change domesticated animals, which are animals we consciously breed for certain traits, but instead on animals that change to adapt to our influence on the world.

According to a 1985 paper titled Evolution in Reverse: Clean Air and the Peppered Moth, between 1848 and 1895 the darker-coloured peppered moth, the melanic moth, increased in numbers in the city of Manchester from 0% of the moth population, to 98%. However, the reverse now appears to be happening, with the lighter coloured moth now on the rise.

Why is this important? Well authors C.Clarke, G.S Mani and G. Wynne of this 1985 paper argue it is a result of human influence, that the colour variation is a consequence of the Industrial Revolution. They believe the darker coloured moth was more successful during times of increased pollution and the lighter moth less-so. Supposedly this is for reasons of camouflage. That the darker moth could hide more effectively during the Industrial Revolution due to the polluted and therefore darkened environment. However the lighter moth is now more successful due to a less polluted and clearer world.

In 2001 British geneticist and Professor of Evolution Michael Majerus conducted a seven-year experiment to test this theory. Published in 2009 his findings appear to agree with this theory and stated that these changes are ‘one of the clearest and most easily understood examples of Darwinian evolution in action’ (Majerus 2009).

Now this example of human influence is one of the clearest. However our effect on plants and animals stretches across the globe and our influence is so often more damaging than this. Part two of this blog series will explore the more damaging effects of ‘unnatural selection’ and how we humans are changing the world and its organisms. Though not necessarily for the better.

References:

Clarke, C., Mani, G. and Wynee, G. (1985). Evolution in reverse: clean air and the peppered moth. Biological Journal of the Linnean Society, 26(2), pp.189-199.

Majerus, M. (2008). Industrial Melanism in the Peppered Moth, Biston betularia: An Excellent Teaching Example of Darwinian Evolution in Action. Evolution: Education and Outreach, 2(1), pp.63-74.