Charles Darwin once said, "Innumerable species, genera, and families of organic beings, with which this world is peopled, have all descended from a common ancestor...Therefore I should infer from analogy that probably all organic beings which have ever lived on this earth have descended from one primordial form, into which life was first breathed."(Ch. XIII) Evolution is the process in which living things change with time. Even though the idea of evolution was established way before Charles Darwin, it was he who made it known to many and. In the 1850s, Charles Darwin's proposed one of his greatest ideas, natural selection, which is the driving force of evolution. As time progressed towards our modern time, scientists discovered a new useful tool that would help show the real truth of our existence. That tool was DNA. DNA has been an ultimate tool for showing that evolution is true, for it contains all the information of all living things and of their ancestors. It can help find the origin of all living things and show how each organism became different from one another and how we evolved to be so. But not everyone agrees with evolution and so, they have different stories of how we came into existence. Evolution is true because DNA forensic record agrees with it.
To understand some of the true nature of things, we have to see them through the eyes of others, meaning we should look at the theory of evolution from both sides, the evolutionists and the creationists' points of view.
An evolutionist's point of view on the matter we all know is that it happened, but we'll make it more specific. Evolution has turned into "facthood" with supporting evidence piling up and is still called a theory. And just like the theory of gravity, it is a fact. Evolutionists use what Darwin proposed- the theory of evolution- and have gained supporting evidence to strengthen its credibility. The idea that all species are descended from common ancestors is what all evolutionists, including Darwin, base their whole argument on. They believe that evolution into new species was based on chance and geographic terms. DNA supports this by showing the sequence of each evolutionary change between species, from physical form to digestive metabolism is due to and recorded in, the changes in DNA. "Every drop of blood contains a history book written in the language of our genes," says Spencer Well, a population geneticist.
The creationists on the other hand find it hard to accept the evolutionary theory, even though it has a large body of supporting evidence. In an article in National Geographic, David Quammen writes that many strong religious groups, like the ultra orthodox Jews argue with the thought that we descended from earlier primates, because it disagrees with a strict reading of the Book of Genesis. Their discomfort is paralleled by Islamic creationists like Harun Yahya, who points to the six-day creation story in the Koran as literal truth and says that the theory of evolution is "nothing but a deception imposed on us by the dominators of the world system."(6) Other people, not the literalistic ones, are also unable to be persuaded by evolution. According to a Gallup poll in February 2001, Quammen learned that no less than 45 percent of the responding U.S. adults agree that God created us the way we are today, like he did 10,000 years ago or so.(6). Evolution to the creationists plays no role in shaping us.
Evidence of evolution comes primarily from four sources: fossil record, chemical and anatomical similarities, geographic distribution of related species, and genetic changes over generations. Remains of plants and animals found in sedimentary rock deposits give us a distinct record of past changes through time, at great intervals. Evidence gathered by Nobel Prize winning scientist Linus Pauling, proves the fact that there has been a great variety of living things and their existence proves that species are not fixed but can evolve into other species over time. The evidence also shows that what seem to be gaps in the fossil record are because of "missing links." These so-called gaps or "missing links in the chain of evolution" are filled with transitional species and their fossil specimens. One of the first gaps to be filled was between small bipedal, meaning two legged, dinosaurs and birds. Just two years after Darwin published On the Origin of Species, a 150-145 million year old fossil of Archaeopteryx was found in southern Germany. It had jaws with teeth and a long bony tail like a dinosaur, and broad wings and feathers like a bird, and has skeletal features of both. This discovery confirmed the assumption that birds had reptilian ancestors. Since the discovery of the Archaeopteryx, there have been many other evolutionary gaps filled in the fossil record. Perhaps, the most important one, from our viewpoint, is the gap between apes and our own species. Since the 1920's, there have been literally, hundreds of well dated intermediate fossils found in Africa that were transitional species leading from apes to humans over the last 6 to 7 million years. The fossil records also give us abundant evidence that the animals and plants of today were preceded by earlier simple ones. Pauling says "This shows that multicelled organisms evolved from the first single-celled ones."
Chemical and anatomical similarities add on to the proof of evolution. In an article in National Geographic the author points out that, "Living things on earth are basically related in the way that their basic anatomical structures develop and in their chemical compositions. No matter whether they are simple single celled organism or a highly complex living thing with trillions of cells, they all began as single cells that reproduced themselves by the similar division processes (Quammen 22). All living things on earth share the ability to create complex molecules out of carbon and a few other elements. All plants and animals get their traits from their parents by inheriting particular combinations of genes. Gregor Mendel discovered genetic inheritance during the time of Darwin, by conducting an experiment to see how inheritance works. He did his experiment by using different generations of pea plants and using their seeds to procreate the next generation and keeping careful records. He found out that purebred red-flowered plants only produced more red-flowered plants. He then crossed the strains of his plants. He bred white-flowered plants with the red ones, and collected their seeds and planted them spring after spring, observing their characteristics. He then concluded that if you bred a white-flowered plant with a red one, you wouldn't get a pink-flowered plant, but a plant with specific traits from its parents. In other words, if you breed tall plants with short plants, you wouldn't get average sized plants, but plants that would be either short or tall. Linus Pauling says "Molecular biologists have discovered that genes are, in fact, segments of DNA molecules in our cells. These segments of DNA contain chemically coded recipes for creating proteins by linking together particular amino acids in specific sequences." Although we have a great diversity of life on our planet, the simple language of the DNA code is the same for all living things. This is saying that in all living things, there is a strand or part of our DNA that is the same. This is evidence of the basic molecular agreement of life.
An additional indication to patterns of past evolution is found in the natural geographic distribution of related species. It is obvious that remote land areas, island groups, and bodies of water usually evolved their own special type of plant and animal communities. Take Palau's famous Jellyfish Lake for example. Before 60 to 40,000 years ago, those jellyfish were hunters, they had the ability to catch their own food and protect themselves from predators. However, being isolated for those thousands of years has caused them to adapt to their new environment, making them lose their stinging tentacles, which were used for catching prey, and getting their food through photosynthesis. Pauling says that places like Hawaii and New Zealand, have indigenous organisms, that won't be found anywhere else in the world. The contribution to these evolutionary changes is caused by the isolation of the organisms for eons from the rest of the world.
Sometimes the environment changes and it is too extreme for the organisms that live in the environment. This results in death to most of the inhabitants to the environment. As Charles Darwin observed, however, not all of them die. Luckily the populations have genetic diversity. The individuals that do survive will most likely be the ones to reproduce and have their traits of survival pass on to the next generation. This will result in evolution of the population. Organisms that mature sexually and reproduce many offspring quickly have a greater chance to go through or experience evolution faster than usual. Germs and bugs are great examples for experiencing evolution at a fast pace. Every time you make a new insecticide or medicine to fight off these organisms, not all of them die. In fact, those that survive reproduce and pass on their survival skills to the next generation. This makes the newer generation more immune to the pesticide or drug. That's why bug spray doesn't always work and why influenzas are becoming more severe as time progresses.
Common ancestry is the part of evolution that helps us look back in time, using DNA sequences or fossils, and finding related species joining at their ancestors. This idea leads to strong and testable predictions about evolution. In Why Evolution is True, Jerry Coyne points out, "If we see that birds and reptiles group together based on their features and DNA sequence, we can predict that we should find common ancestors of birds and reptiles in the fossil records. And if they are proven correct, we can too find our common ancestor with other primates." (10)
Gradualism is the part of the evolutionary theory that takes many generations to produce substantial evolutionary change, such as that of bird from reptiles. Changes in features don't just happen in one or two generations. They take hundreds or thousands generations to change. In microbes, meaning germs and bacteria, they have really short generations, some as short as 20 to 30 minutes. That means that they can go through evolutionary changes quick and faster than more complex organisms. This is the reason why you can get the cold over and over again, because the bacteria or virus is constantly evolving and becoming more resistant to drugs. Gradualism means that each species evolves at it own pace rather than an even pace. So when a plant or animal settles in a new environment, they can evolve at a faster rate. But when the plant or animal becomes well adapted in the environment, the rate of evolving slows down.
The next and probably the most important factor to evolution is the idea of natural selection, which is the driving force of evolution. The Ultimate Visual Dictionary of Science's definition of natural selection is, "when within a species there is always variation; some individuals are more successful than others in the struggle for survival and are more likely to breed and pass on their advantageous characteristics." What this is saying is that, species that have adapted to survive in a particular place will pass down that trait of survival to the next generation and so on, until they show distinct changes in characteristics and features that were not shown or possessed by the parent species. So natural selection only improves what came before it. It makes the fitter, not the fittest.
The next part of evolution is called speciation. Speciation is the evolution of new populations that are reproductively isolated from other populations. In this part of evolution, it shows how different groups cannot interbreed and/or exchange genes. There are many ways why this can happen. One, each species doesn't find each other attractive as mates and two; if they do their offspring will be sterile.
And this brings us to the final point of evolution which is nonselective mechanisms of evolutionary change. The most important thing about this idea is simple random changes in the portion of genes caused by the fact that different families have different numbers of offspring, leads to evolutionary change, which has nothing to do with adaptation. "This change in the frequency of genes over time is called genetic drift and is a legitimate type of evolution, because it involves changes in the frequencies of alleles over time" (Coyne 123).
As you can see, the evidence of evolution is so overwhelming that it makes evolution a possible solution for how life came into being and how we all share a common ancestor. I have read books and articles, and have shown you some of the best evidence, like DNA, fossils, and natural selection, and they are all saying the same thing, Evolution happened and is even happening right before our eyes. It will just take a while for a species to gradually change into a new one, but unfortunately, that takes time, so "Preserve the old, but know the new."-Chinese proverb.