Today is the 150th anniversary of the publishing of The Origin of Species or its full title: On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. This earth shaking work, by Charles Darwin, introduced the world to the concept of natural selection as a driving force of evolutionary change. I have been wanting to write about the basics (and I do mean basics) of evolution for a while, so I thought that I would start today.
Why am I doing this? I love biology, and the theory of evolution by natural selection is one of the most elegant (in my opinion) and simple theories in science. I want to share my understanding of this fascinating subject that underpins modern biology. And I love to teach, to tell, to share the wonder I have about the natural world with as many people as possible.
I find that many of the people that denounce the theory of evolution have little understanding of it, nor science in general. I intend to explain things in my own time. I might miss something, or gloss over it. Please, dear reader, ask questions. I crave dialogue and discussion, and although we may not agree, I will listen to you, if you grant me the same courtesy. I will not formerly list sources, as a lot of this material has built up over time from various books, lectures etc. If you would like some reading suggestion, again please ask!
To some, the theory of evolution is wrong simply because organisms *look* designed. They seem to do what they do so well that how could they be anything but designed? It also does not help that we live in a world filled with things that we humans have designed and function well in the role they were designed to fulfill. In a way, you could look at natural organisms and say that they were designed: designed by the slow, incremental process of natural selection. This is not my idea, but it is an interesting way to look at natural selection. Note that there is no mention of an external designer. In the case of natural selection the “designer” is simply the environment (including non living and living factors) that the organism must survive in…
I am getting ahead of myself, so I will pause for a moment to discuss to terms that will appear every now and then. The terms are ‘evolution’ and ‘natural selection’. Evolution simply means change. We use this term all of the time, in a variety of contexts. For example, we might say that a band’s music has evolved to be more mature over the last decade. You might remark that your attitude toward child poverty has evolved after you visited an orphanage in the Honduras. Evolution in biology has the same meaning! Evolution is just the change of organisms over time (time in this case is an extremely important idea, and I will return to it later…). These changes build up until new species are formed and the tree of life branches. Natural selection is the idea of natural processes (environment, predators, diseases, population pressures, parasites, etc) ’selecting’ for useful traits. Darwin, in Origin, used the analogy of artificial selection to help explain it. Most farmers, animal breeders, orchid growers out there know that if there is a trait that you desire in an organism, you look for organisms that posses that trait and then breed them, hoping the offspring will also have that trait. In natural selection, an organism might have some small mutation(more on this term later as well) that helps the organism survive just a little better than its neighbors. It is able to reproduce and pass on that mutation to its offspring. Over time, all of the organisms of that species has that trait. For example: all humans are bipedal, but most chimpanzees are not. At some time in our history, some distant ancestor started walking on two legs. It proved a useful strategy for something, and now we walk upright. So natural selection is simply the environment selecting traits. Blindly selecting traits, I will add. There is no farmer choosing the traits… Hence the ‘natural’ designation.
I think that is enough for one day. Next time I will talk more about the changes or mutations that cause the different traits for nature to select…
Scott
