In the mid-1800s, the scientific maverick Charles Robert Darwin unearthed and described a fundamental biological principle that would go on to transform our understanding of the origin, evolution, and nature of life. Darwin informed humanity that the organisms that make up the ecosystem of the Earth take part in a never-ending struggle for existence, in which those organisms that are best suited, trait wise, to the conditions under which they live are at an advantage, in the sense that they are more capable of surviving and reproducing than organisms that are not as well equipped to deal with the challenges and obstacles they face.
The implications of this assertion are that heritable traits that are beneficial under the existing environmental conditions become more common over time, whereas deleterious traits are weeded out, and that life has changed (evolved) over time. There is no governor that oversees everything and decides what is to happen; rather, the changes occur naturally as a result of variation in reproductive success.
In light of the information we have at hand today, it’s quite obvious that Darwin was right. One doesn’t even have to look at any of the countless scientific experiments that have verified his seminal theory of evolution to reach this conclusion; all one has to do is inspect how things work in nature. Given that one is perceptive and possesses basic knowledge about genetics and heritability, one will quickly deduce that organisms take part in a battle for existence, in which the “winners” are those that are best suited to their environment.
The theory of natural selection confers humanity with the basic means to understand life: how and why species emerge and go extinct, why organisms instinctually operate the way they do, and why there is such an abundance of varied life in nature. It’s almost impossible to overestimate the value and usefulness of Darwin’s principle theory. Pretty much everything that has to do with life on Earth can be effectively organized and understood via Darwinian thinking.