In urban areas, where human impact is most obvious, many studies have shown that plants and animals, native and introduced, are evolving in response to human transformation of the environment.
A famous example is so-called ‘industrial melanism’. It led to a dramatic drop in the numbers of light-coloured peppered moths in England during the 1800s when industrialisation led to pollution covering tree trunks, camouflaging dark-coloured individuals from bird predators. But when the pollution was finally cleaned up in the 1970s the situation reversed and dark-coloured moths began to be preyed upon in ever increasing numbers shifting the population accordingly.
Other documented changes include shifts in the colouration of feathers in bird populations living in urbanised areas, resistance to severe pollution of waterways by fish, and weeds growing in paved areas ceasing to disperse their seeds.
But antibiotic resistance stands as one of the clearest examples we have of evolution in action among contemporary species. It’s clearly also bad news for human health and our attempts to control infectious disease, with the race to discover new kinds of antibiotics to combat widespread microbial resistance faltering.
What about humans then? Perhaps most surprising is that these impacts will very likely alter the course of our evolution as well. We are still evolving after all, and in sometimes surprising ways. And what affects other species affects us too, as we can’t possibly escape the profound environmental changes underway at present.
We can find dramatic examples of human evolution in the past, and they have chilling parallels with the present. The best one is the development of agriculture between 10,000 and 5,000 years ago. It happened in at least nine different places, independently, and was in most cases associated with major environmental, social and economic changes.
It led to large-scale human migrations, the rapid spread and homogenisation of languages and culture, and major changes in technology. There were major shifts in human settlement patterns, lifestyles and social conditions, with people occupying smaller areas of land, living in higher densities, becoming much more sedentary, and for the first time, urbanised.