Charles Darwin Theory of Evolution by Natural Selection
Contrary to popular belief, The Theory of Evolution is not the "we come from monkeys" theory as some religious fanatics would have you believe. Evolution has a long history of scientific research to support its claims and is a very respected theory in the would of science. Before you simply discount Evolution as some crackpot idea, learn what it is and what it means before making any judgement as to it's validity. You may see many different applications of the theory to things that you observe in your own life.
History of the Evolution Theory
When Charles Darwin first published his research on Evolution, there had already been another man who was independently working on the same theory. This man was Alfred Russel Wallace. Both men are now credited with the discovery although Charles Darwin is still the most commonly known for it in the non scientific arena. Darwin had been working on his theory for quite some time but was originally hesitant to publish his findings because he was a very devoutly religious man.
The Theory of Evolution was revolutionary for it's time. This is because the church and the head of the church; Pastor, Pope, Reverend, etc., was the main source of knowledge during that time. The head of the church was well respected and typically the most educated person in the community. The Theory of Evolution contradicted so much of what Creationists believed. The main contradiction was that Creationists believed that God created every creature to be perfect and therefore that being would never change. Evolution is all about change.
Theory of Evolution Definitions
Evolution: The change in allele frequency over time. This is not an overnight change or over a few years. Evolution take hundred and thousands of years. It is not a fast process.
Allele: One member of a pair of genes. Alleles can change how we look, act, feel. Our alleles code for what we are.
Ancestor: When this word is used in regards to Evolution, we are not referring to a recent ancestor like a grandparent or even great grandparent. Ancestor can refer to someone/something in an object's genetic lineage for hundreds, thousand, millions or even billions of years ago.
Small Ground Finch
Natural selection is the main avenue for evolution to take place. In order for natural selection to take place, four things must be present.
- There must be variation among the species. They can not be exactly identical in all ways.
- The variations must be heritable, able to be passed on to the next generation.
- More offspring must be produced than what can survive. Some of the species with live to reproduce and some will not.
- The individuals that survive and reproduce have a certain trait that enabled them to survive better than the others.
Natural selection causes a population of individuals to change in relation to what will help them survive better in their environment. Each individual does not change but each subsequent generation shifts to be for like the individuals that survive the best in that specific environment.
Darwin studied Ground Finches on the Galapagos. When he first because, he noticed that some Finches had long, narrow beaks, some had short, wide beaks and some had all kinds of types in between. Over time, he noticed that more and more Finches started having deeper beaks. The average beak depth over time had increased! Evolution by natural selection can explain how this is possible.
Soon after the Finches began being studied, there was a severe drought on the island. This was a drastic change in the environment that the finches lived in. The drought made it to where very few plants could produce seeds. These seeds are what the Finches survived on. The only plants that were able to produce seeds had their seeds deep inside and were more difficult to get to. This made it so that the finches with shorter, wider beaks couldn't get to their food source. The result was that mostly, only the birds with deep beaks were able to eat and were more likely to survive the drought. To reproduce and pass on your genetic material, you must survive. Therefore, more of the reproducing finches had deep beaks. This means that more of the offspring had deep in beaks. This was a change in allele frequency in the population as a whole.
A simple way to understand natural selection is that if you die, you can't have babies. If you can't make babies, you can't pass on your genetic material.
Vestigial traits give one way of proving proof of evolution and support the Theory. A vestigial trait is something that is reduced in size and function or has no function at all in comparison to the original function of the feature. These vestigial traits are left over from an ancestor and prove the relatedness of the two species.
Some examples that are found in humans are the existence of goosebumps and our tailbone. Goosebumps usually appear when we are scared, excited or even cold. If you look at a primate when they are experiencing the same things, you will notice that their hair is standing straight up. The hair is erected by the reaction of "goosebumps" to look more intimidating and larger in the presence of fear and excitement and for insulation in the cold. Therefore, we still get goosebumps for the same reason but over time humans have lost the trait of long or thick hair on our bodies. Our goosebumps no longer have a purpose but remind us of our distant common ancestor with the primates. This doesn't mean we came from primates, only that somewhere in the distant past, we were somehow related to one another and shared a common ancestor.
Another example of a vestigial trait humans have is a tailbone or coccyx. We have no tail, but still have the bone structure that would have supported a tail. Our coccyx is completely non functional and essentially useless to us. However, it is left over evidence of our ancestors. In the picture below, you can see how similar our bone structure is to that of primates. This is no coincidence.