The Visible Effects of the Human Factor on Evolution

Just yesterday I was in the car with my partner when a squirrel ran across the road, stopping and starting. I found it nerve wracking to watch as the little beggar prancing across the slushy street with no obvious regard for the oncoming vehicles. The squirrel made it safely to the other side but its perilous journey made me pause and consider what effect human environmental pressures will have and already have had on the evolution of plants and animals.

Will squirrels, possums, raccoons and feral cats become smarter over time and learn to look both ways before crossing the road? Or will they become better at producing fuzzy little offspring? Will they become faster or more decisive? Or have we killed off enough of their natural predators to make it a wash with the number of critters we crush under our cars?

Plants are already feeling the pressure of human civilization. Purposeful domestication of plants aside, we've been changing plant life by our practices unintentionally as well. Everywhere, there are short, sturdy dandelions and violets which bloom almost flush to the ground as a result of the kooky human preoccupation with manicured lawns.

Our waste chemical production is immense and some of it makes it, unprocessed, into the environment. Recent tests have even found detectable levels of pharmaceuticals in our lakes and streams. Apparently some of the leftover drugs we pee out of our systems make it past the sewage treatment plants. Will this "stuff" provide environmental pressure for thousands of species of plants and animals causing some to be "selected" for toxin resistance while others just die off?

And what about us? With the advent of effective birth control, will we produce more fertile descendants? We all know a few people who are the result of unintended pregnancies. While some unintended pregnancies are just statistically likely or are the result of improperly used birth control there are probably a few that just come from extremely fertile parents or those whose bodies are naturally resistant to hormonal birth control.

Even if we make intense efforts to minimize our environmental impact through ecologically sound or "green" living the effects of thousands of years of human civilization will be felt by every living thing far past our life spans. We have already left our imprint on the very genes of countless organisms. Like it or not the human race is a vast force of nature whose impact on the environment and the evolution of species around us will resonate for ages to come.