Evolution is defined as the change in frequency of genetically determined characteristics within a population over time. There are three key points to consider when referring to this definition. First, evolution only occurs in populations, which are defined as groups os organisms of the same species that are able to interbreed and are genetically similar. Second, genes determine the characteristics displayed by organisms. Third, the mix of genes within a population can change and evolution involves changes in the genes that are already present in a population. One additional piece of information to keep in mind when discussing evolution is that individual organisms do not evolve, only populations can evolve. Evolution occurs by a mechanism called natural selection, a process that encourages the passage of beneficial genes to future generations and discourages the passages of harmful or less valuable genes through sexual reproduction.
In order to better understand the theories, controversy, and misconceptions that surround evolution, it is beneficial to reflect back on the history of evolution’s great thinkers and their theories. Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist and encyclopedic author born in 1707. He had an influential effect on other great thinkers like Jean-Baptiste Lamarck and Georges Cuvier and is best remembered for his 35 quarto volumes of his Histoire naturalle. Buffon is also noted for Buffon’s law, which states that despite similar environments, different regions have distinct plants and animals. He argued that species may have both “improved” and “degenerated” after dispersing from the center of creation and that climate change may have facilitated the worldwide spread of species from their centers of origin. More importantly, Buffon noted the similarity between humans and apes but ultimately rejected the possibility of common ancestry. Something that would later become a parallel to another scientific discovery. Furthermore, Buffon speculated that planets had been created by a comet’s collision with the sun. He also suggested that the earth originated much earlier than 4004 BC, the date famously determined by Archbishop James Ussher.
William Paley was an English Christian apologist, philosopher and utilitarian born in 1743 who is known for his teleological argument for the existence of God in his work Natural Theology, published in 1802. Natural Theology argues that God’s design of the whole creation could be seen in the general happiness, or well-being, that was evident in the physical and social order of things. His argument is primarily built around anatomy and natural history. Paley had this to say in regard to human anatomy, “The necessity, in each particular case, of an intelligent designing mind for the contriving and determining of the forms which organized bodies bear.” Paley is also known for his famous “watchmaker analogy”, a teleological argument that states that design implies a designer. The analogy has played a prominent role in natural theology and the "argument from design," where it was used to support arguments for the existence of God and for the intelligent design of the universe.
Jean-Baptiste Lamarck was a French naturalist and biologist born in 1744. Lamarck is known for his work on the inheritance of acquired characteristics. Lamarck’s biological work is characterized by two main principles, environment gives rise to changes in animals and that life is structured in an orderly manner where many different parts of all bodies made it possible for the organic movements if animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of his first principle. Lamarck also believed that there were two forces that comprised evolution, the complexing force or the tendency for organisms to become more complex and the adaptive force or the adaptation of organisms to their environment. Lastly, Lamarck noted the complexifying force or the tendency for organisms to become more complex, moving up the ladder of progress.
Georges Cuvier was a French naturalist and zoologist born in 1769. Cuvier studied mummified cats from Egypt and said that they were no different from their living counterparts and argued that this showed that life forms did not evolve over time. At the time Cuvier presented his paper on living and fossil elephants it was widely accepted that no animal had ever become extinct. Cuvier was also a believer of catastrophism, the geological school of thought which maintained that many of the geological features of the earth and the past history of the earth could be explained by catastrophic events that had caused the extinction of many species of animals. This school of thought later lost ground to a new school of thought known as uniformitarianism, which claimed that the geological features of the earth were best explained by currently observable forces, such as erosion and volcanism, acting gradually over an extended period of time.
Arguably, the most influential person in regard to evolution is Charles Darwin. Charles Darwin was an English naturalist born in 1809. In 1831, Darwin accepted a naturalist position aboard the HMS Beagle, commanded by Robert FitzRoy. On the five year voyage around the world Darwin collected specimens, including birds, plants a fossils. Upon his return to England in 1836, Darwin began to write up his findings, published as part of Captain FitzRoy’s larger narrative and later edited into the Zoology of the Voyage of the Beagle. The trip had a monumental affect on Darwin’s view of natural history. He began to develop a revolutionary theory about the origin of living beings that was contrary to the popular view of other naturalists at the time. Darwin’s study of finches in the Galapagos Islands was perhaps the catalyst to what would become the most revolutionary theory of all time. Darwin noted that many of the finches had different beak sizes, but were all the same species. He began to wonder why God would put different species of birds on different islands when the climate was the same on all the islands. It was his belief that natural ordinary causes caused this, not God. This initial discovery then led to his later theories published in On the Origin of Species, in which he describes his theory that all humans evolved from a common ancestor through a process called natural selection. His theory was extremely controversial and sparked fear among the people. People viewed his theories as incompatible with the word of God and they also threatened the social order and class systems of the time.
It has always been my belief that the evidence for evolution is irrefutable. I believe in Darwin’s ideas, including the idea that humans evolved from one common ancestor. Evolution for me has never been controversial, threatening or anything other than scientific fact. As far as creationism goes, I do not believe that God created man as it is portrayed in the Bible. I do not believe that God created Adam and Eve, land animals, trees or any other specific parts of Earth. However, the gray area for me is how Earth got here in the very beginning. I am willing to believe that it is possible that God created the Universe or the first amoeba. For me, there is not scientific proof that the stories of the Bible are true and there is no scientific proof of God. Finally, if we can prove evolution and disprove many of the biblical stories, than it seems more sensible to define God as the creator of the first organism rather than making false claims about creation. I am not devoutly religious and frankly not religious at all, but I am not so naive to discount the existence of some sort of creator. I just find it rather insane to “not believe” proven scientific facts.
Evolution is happening all around us every day in almost every living thing. We don’t notice it because it such a slow occurring process, often taking thousands and thousands of years. The evidence for evolution is so strong and so plentiful, here are just a few of the examples of how evolution works. Similar to Darwin’s finches, researcher Chris Schneider studied 550 different species of birds at different elevations in Ecuador. He found that the beaks of the birds had evolved differently according to the flowers they fed on. If the flowers were longer in shape, then the beaks of the birds were longer and vice versa. He also found that the hummingbirds of the Andes highlands had adapted to the cooler temperatures of the area. This shows how environmental changes lead to changes in body characteristics. These changes in bodies is also seen in moles and owls. Mole’s eyes have gotten smaller over time because they rarely use them, while owl’s eyes have gotten larger over time because they rely heavily upon their sight for survival. Creationists argue that the human eye is proof that God created all humans because the eye is so miraculous. In reality, there are many imperfections with the human eye and those imperfections serve as proof that evolution does exist. Because the eye evolved over time, the eyes of all vertebrates have a blind spot right in the center and evolution has to work around what is already there. Further, there is scientific proof of how eyes actually evolve. First, a flat patch of light sensitive cells form that can detect the direction of a light source. Second, a small depression in that flat spot forms and becomes cup shaped. The cup eye can detect movement and is found in flatworms. Third, the slit eye forms in which there is constriction of the opening of the eye. This type of eye is found in the chambered nautilus. The last step in the evolution of the eye is the formation of a two layered lens with fluid in between causing it to become convex. This is the type of eye humans have (Darwin’s Dangerous Idea, 2001).
A great way to understand just how long evolution takes is through the clock analogy which says to view life from the beginning to the end like an hour on a clock. Of that one hour, single-celled organisms make up the first fifty minutes of that clock, animals make up the last ten minutes and humans only account for the last one hundredth of a second on the clock (Great Transformations, 2001). Understanding how long it takes for animals to evolve makes it easier to understand what seem like bizarre evolutionary changes. One of the evolutionary changes that scientists struggled with for many years was how did whales end up in the water? When mammals appeared over 200 million years ago they evolved on land, so how exactly did whales evolve? A scientist doing research in Pakistan discovered a skull that he could not identify. The skull looked similar to a wold skull and had a distinct inner ear only found in whales. This was one of the first transitional forms discovered that proved whales did go from land to water. The Basilosauras, a transitional form of a whale that had four legs, is also proof that whales evolved from land animals believed to be a wolf like creature. Over time, as their legs became less necessary, they evolved into fins that were more beneficial to a sea creature. Additional proof that whales were once land mammals is in their spines. When whales and dolphins swim their spines flex up and down just like land mammals who run, while fish flex their fins from side to side. Before land animals evolved into sea creatures, fish evolved into land animals known as amphibians. A researcher in Greenland discovered tetrapods, animals with four limbs, were actually fish with legs and fingers. Proving that fish first developed legs and arms and then came out of the water. Further, tetrapod limbs already have many of the basic parts seen in a human arm, such as the two main bones, a wrist and fingers. Natural selection allowed each of these species to evolve in ways that were more beneficial to their survival (Great Transformations, 2001).
How is it that we have gone from microorganisms to dinosaurs to humans? Some would argue it must be the work of a divine power, but there is another answer, mass extinction. Extinction occurs when a species is completely wiped out. Sometimes this is gradual when that species can no longer adapt and survive and other times one catastrophic event is to blame, like when dinosaurs became extinct. Whatever had survived the permian extinction later became dinosaurs. The dinosaurs grew so large in size because they had no competition for resources. The KT event that killed all the dinosaurs left only small rodents who were able to burrow able to survive (Extinction!, 2001). This caused the mammalian population to become the dominate animals on Earth. Lastly, any time an extinction occurs and a species dies out, it opens the door to new genetic variability and the rise of a new species.
Evolution also plays a role in everything from predator-prey relationships, sexual reproduction, including the mates we choose and our health. Some animals adapt and evolve to protect themselves from predators. For example, why does the toxic newt secrete poisons strong enough to kill 12 adult humans? Originally the newt may have only been slightly poisonous to protect itself from predators but, over time the predators evolved to become more resistant to the toxins and therefore, the newt also evolved to become more toxic (The Evolutionary arms Race, 2001). Evolution also plays a role in sexual reproduction, right down to the mates we choose. Studies have shown that organisms who reproduce sexually fair better than those who reproduce asexually. This is because of genetic variability. Researcher Robert Vrijenhoek studied minnows from the same pond, some of which were asexual reproducers and some who were sexual reproducers. What he found was that the asexual reproducers in the pond had a higher rate of black spot disease than the sexual reproducers. After a drought many of the sexual reproducers died and the rate of black spot disease in them increased because less genetic variability made them more vulnerable to the disease.. As an experiment he went downstream and collected minnows and introduced them to the pond with the sexual reproducers who had increased rates of black spot disease. He retuned a year later to find that the disease had completely disappeared because of higher genetic variability among the sexual reproducers. Thus, sex generates variation and increases survival (Why Sex?, 2001).
In addition to genetic variability, evolution also influences the choices many animals make when looking for a partner in order to pass their genes on to the next generation. Darwin was confused by the ornamentation of many male species, like peacock’s tales and lion’s manes, because these ornamentations make survival harder and don’t seem to benefit them. However, these ornamentations are related to sexual selection for survival and make males more attractive to females for reproduction. One experiment with peacocks showed that only healthy, strong males can grow a large tail. The researcher clipped the tails of some of the peacocks, leaving them with fewer eye spots. The males with smaller tails and fewer eye spots were not selected as mates. The conclusion was that the offspring of males with large, healthy tails lived longer and were healthier than the offspring of males with smaller tails. Another study in the field of evolutionary psychology had similar results. Men were told to sleep in the same shirt for a few nights so that their scent was left on the shirt. The shirts were then transferred into bags and without knowledge of the men’s appearances, women were asked to select the shirt that smelled the sexiest. The women chose the shirts of men whose genes differed most from theirs. It seems that there is an evolutionary process which occurs here. In order to have the best possible outcome for one’s offspring, genetic variability as well as a healthy mate is key. Both of these determinants in mate selection can be seen in humans and throughout the animal kingdom (Why Sex?, 2001).
Another example of how evolution is constantly at work, and perhaps a more noticeable example is evolution’s role in drug resistant forms of disease. Tuberculosis and HIV are two examples of diseases that are extremely difficult to treat because they often evolve into drug resistant strains that become harder and harder to treat. One of the reasons HIV is so hard to treat is because drug resistant form of the virus survive through natural selection and then those drug resistant strains reproduce. Patients are frequently switching drugs and the virus continuously adapts to resist them. One way doctors are trying to beat evolution in this case is through treatment interruptions where the patient ceases all treatment for three months causing the resistant cells to disappear. In the drug-free environment which in this case is the patient’s body, non-resistant cells then begin to reproduce and take over. Then doctors flood the body with drugs all at once in hopes to rid the body of HIV. Tuberculosis also has a tendency to develop into a drug resistant strain that becomes very difficult to treat. The even scarier part is that if you contract TB from someone who has the drug resistant strain, you too will contract drug resistant TB. Researchers attribute this drug resistance to the overuse and misuse of prescription drugs, citing that over 50% of prescriptions are unnecessary (The Evolutionary Arms Race, 2001). Not only does evolution make HIV and TB difficult to treat, it could also be the answer to a cure one day. Researchers found that there is a mutation present in about 10% of European caucasians that makes them immune to the HIV virus. However, native Africans and East Asians lack this immunity. Why? This mutation only exists in European caucasians because it is the same mutation that protected their ancestors from the Bubonic Plague. This is a prime example of how natural selection works within a population.
In the above information I have explained the physical evolutionary process and its inner workings, like how whales became sea creatures, but the more important evolutionary process for most of us is that of humans. Scientific evidence proves that we share 98% of our DNA with chimpanzees (Darwin’s Dangerous Idea, 2001). Does this mean we evolved from monkeys, chimpanzees, or apes like many people think? No it does not. First, there are staggering differences between apes and chimpanzees. No one is claiming that we evolved from any kind of monkey, chimpanzees included. The scientific facts say that we shared a common ancestor millions of years ago with chimpanzees. It was at that time 6 million years ago that hominids branched off from the common ancestor shared by chimpanzees. From this branch came the Neanderthals and Cro-Magnons. Both showed regularity in thinking by using tools, however differences there were many differences between the two. Cro-Magnons developed characteristics still carried by modern humans, like the use of symbolism, ritualistic burials and advanced weaponry. Our direct ancestors began leaving Africa 60,000 years ago heading into Asia. archaeologists in Turkey have found 40,000 year old beads that give insight to early human life. The beads not only show creativity in the brain, but give reason for social standing and social relationships among those people (The Mind’s Big Bang, 2001).
The only reason reason evolution is debated, hated, or controversial at all is because for many people it cannot coexist with their religious beliefs that say God created man. This is the same issue that students at the prestigious, yet conservative Christian college of Wheaton University find themselves grappling with on a daily basis. Wheaton College has become the epicenter of debate between anti-evolution creationists and Christians who feel that evolution and religion can coexist. Author Ken Ham, a fundamentalist Christian, Biblical literalist and young-Earth creationist, argues that the Universe was created 6,000 years ago, and that Noah’s flood occurred about 4,500 years ago. He also believes that the animals carried on Noah's ark produced the biological diversity observed on Earth. Ham also believes that dinosaurs co-existed with modern humans. He supports his view with biblical scripture. While this argument may account for the presence of dinosaurs it still leaves one small problem. Fossil records and carbon dating prove that humans and dinosaurs never roamed the earth at the same time and therefore were not on Noah’s Ark together.