To start with the topic of our effect on the world, we must ask ourselves - just how we do it? Moreover, did we changed the world for the better - by creating the Suez and the Panama channels, drained disease-causing swamps, made cities and roads... and even the pyramids and the Sphinx? On the other hand, did we create something else in the process of our evolution, something that may outlast our own cities and even the pyramids? This essay will look at the course of our evolution and try to answer the question.
The side-affect of global change that came from human evolution began at the very start - maybe not exactly at the time of Lucy and other pithecanthropus, but around the Ages of Metal. Back in the Stone Age people were still little better than animals, as fire provided only a slight edge against the dire animals of that time, and when that was not available, then people had problems, sometimes deadly ones, according to the Stone Age's fossils. In other words, we do not possess much evidence about human impact on the world from that age; at that time, we were not that different from the apes to change the world in any great way. When people learned how to make metals, that state of things changed.
By the Ages of Bronze and Iron, the situation changed, as people progressed to the point where they got a much-bigger edge over other forms of life on the planet. In addition, this edge transformed into not just knowledge of metalwork and various things that people can make with it, including ranged weapons that can kill almost anything from a great distance; also, it is our taming or domesticating of such animals as cattle, horses, and dogs who became our assistants and even friends of sorts. No other mammal (or bird) ever came close to repeating that.
After the stage of domestication was finished, the wheels of the process of progress still went on. People tamed dozens of species of animals, including insects; we also developed hundreds of crafts and skills; in other words, after many pains and gains, we became the dominant species on Earth - and this is where things grow even worse.
Throughout most of the Dark Ages, humans still did not reach their maximum capacity of affecting the natural environment, but they did manage to hunt most of Europe's wildlife to extinction and destroy most of their forests just the same. Everywhere where humans settled in greater numbers and started to build civilizations, all sorts of animals and plants vanished, extinct forever.
The Industrial Revolution, however, put a new spin on things; it added a new factor to the process. With the development of industry, human output in such fields as arts and crafts doubled at least, and so did human influence on nature. Until the Industrial Revolution, human impact on nature was as simple as cutting-down forests for fields and meadows, hunting and fishing (usually to excess). Now, however, people added pollution to the mix.
There is no reason to describe pollution to modern day society - everybody knows what it is and what it does. Back then, though, our ancestors did not know or realize that, so... they had that for an excuse. What is our explanation?
Nowadays people may no longer hunt or fish excessively as they did, say, in the 19th century or even in the beginning of the 20th century because, in part, we already depleted much of the fishing, let alone the game animal stock. Nowadays people no longer cut large patches of woodland (at least in the First World countries) because now there are available alternative fossil fuels to replace firewood. Moreover, pollution... is still very much around, but now people are debating furiously regarding that matter. Is not process of human progress grand?
Furthermore, in the course of the human social evolution, people never really thought about other forms of life on this planet - beasts, birds, trees, etc. As their habitats are vanishing, they either die out or begin to adapt, like rats, or foxes, or termites, or cockroaches, etc. They adapt and begin to change our environment - their new environment - to their liking. People do not like when this happens to them, and so they "strike back". The result of the process can be seen in DDT and other such fun inventions to deal with such pests.
If the talk has turned to household pests, how about spiders? When a writer of the Marvel comics' Spider-Man wrote, "With great power comes great responsibility", he was either very witty or very wise, because at that moment he stated the obvious... for all of us. We do possess great powers of intellect and imagination, and how do we use them? Selfishly, that is how. Moreover, for what do we use them? For destruction mostly, it seems - we are intent on destroying everything on this planet, including ourselves for almost any reason, as shown by the current news; we certainly progressed a long way since the Trojan War, yes?
How can this essay end on a positive note? Only with a lot of optimism from its author. On the other hand, people as whole will need a lot more than just optimism to ensure that the processes of human evolution and civilization do not end at all. Some things were done, like the creation and the preservation of National Parks for wildlife, and that tough problem of pollution is under assault at least verbally. However, these things are not enough. We have to progress (and process) a lot more to undo the last few centuries of our actions, and hopefully this essay will motivate other people to do something along these lines as well.