Charles Darwin Day, on the 12th February each year, is dedicated to celebrating the alternative theory which is overwhelming in its evidence. This Darwin Day we're paying homage to the man by exploring and countering arguments in opposition to evolution.
For a long time, the only accepted explanation we had for life on Earth was creation, that all life zapped into existence within 6 days and that this was done by God. There are other interpretations of creation, but religion is fairly unanimous in advocating the instantaneous formation of the life of today.
It was not until 1859, when Charles Darwin published the book "on the origin of species by means of natural selection" that an alternative explanation was conceived. Unlike creation, Darwin's theory of evolution was not based on myth and scripture, but on evidence and logic. He reasoned that all the species of today could come about gradually, through years and years of progressively small changes, from one common ancestor. Since then, there has been an overwhelming amount of evidence in favour of evolution, principally from the disciplines of palaeontology, genetics and biogeography. Importantly, everything that has been found to date is exactly as you would expect if evolution was true.
However, there are still many people who do not accept evolution. In a study by Miller et al. (2006), the percentage of people who accepted evolution was reported for 34 countries. Only a handful of countries, largely in Scandinavia, scored above 80%. The United Kingdom also scored well and was 6th highest on the list, but the vast majority scored under 70%. One of these countries was the United States of America, one of the most influential countries in the world. It scored just 40% in this study. The US also performed poorly in a survey carried out last year, with 57% of people either not accepting evolution or thinking it is a God guided process (Pew research survey, 2013). For such a staggeringly high figure, you may believe that these people have particularly good reasons for not accepting evolution. But they do not. Over the course of this article, we will go through some of the most common arguments given against evolution, and will explain why they are fallacious.
Evolution is often said to be a theory, and some people will say that is all it is, a theory or a guess; mere speculation. However, "theory" in scientific terms has a deeper meaning than in general public usage. A theory is a collection of ideas that explain some aspect of nature and which is substantiated by considerable evidence. It is virtually fact, just as it is virtually fact that microorganisms cause disease (germ theory), that living organisms are made up of cells (cell theory), and that the Earth orbits the sun (heliocentric theory).
Many people argue that because life is so complex, so intricate, it cannot possibly have come about through chance mutation. One must first point out that evolution does not deal in chance. Yes, mutations occur by chance, but these mutations are then selected for non-randomly, with preferable mutations being passed on to the next generation. It is entirely feasible that an accumulation of these mutations could eventually give rise to something complex and which looks "designed". Life is also full of deficient phenotypes (or observable arrangements e.g. physical appearance) that can only make sense in the context of evolution. The laryngeal nerve, which travels from the brain to the larynx, is just a few inches in length for humans, but in giraffes, the nerve travels down the neck past the larynx, loops beneath the aorta of the heart, before travelling back up to the larynx. This detour increases the length of the nerve by some 12-15 feet. Why the nerve does not go directly between the brain and the larynx lies in their ancestry. Giraffes descended from fish and for them, the nerve did not connect to the larynx and instead supplied the gills. The most efficient route was beneath the aorta, but as evolution progressed and the heart moved further down the chest and the neck lengthened, this route was no longer so efficient and resulted in a poorly "designed" giraffe. Evolution can only work on what came before. It cannot backtrack and rebuild everything from scratch, as the "scratch" state would not be selected for. Aside from the giraffe, there are many more such examples, including the development of hind limb buds in the dolphin embryo, which form but then cease to grow further during the first few months, and the growth of back hair on a human embryo that is subsequently removed after 6 months. Both of these oddities stem from their ancestry, dolphins from tetrapods (four legged animals), and humans from ape-like relatives.
Some features are irreducibly complex. For example, the human eye is only useful in its full form, and half or quarter of an eye - steps in the evolution of the full eye - would be of no benefit and would not be selected for. However, half or quarter of an eye would be beneficial. One can easily see the gains of being able to discriminate between light and dark, as would be the case for a simple eye, and being able to distinguish figures and objects, as would be the case for a slightly more developed eye. As long as each step in the evolution of a feature is adaptive then it will be selected for. It should also be noted that each step does not necessarily have to have the same function as its ultimate form. Take the bacterial flagellum, the tail like limb which is used by bacteria to swim. It is made up of several parts, akin to the rod, motor and propeller of a boat, and if any of these are removed, swimming is no longer possible. However, the bacterium can still do other things. Simpler flagella may serve as a sensory organ, or as a means to infect other cells, as is known from a number of bacteria living today. Once these pre-existing structures are in place, evolution is able to work on them to produce new function.
There is no observable evidence for evolution. Yet, recent news is littered with evidence. The growing resistance of insects to pesticides, for example, is currently a huge concern in agriculture. Over 50 resistance events have been recorded for the green peach-potato aphid, Myzus persicae, a pest of several vegetable crops, including cabbage, pepper and, of course, potato. In the instance of the insecticide, Pirimicarb, which inhibits the enzyme acetylcholinesterase (AChE) and results in paralysis, resistant aphids have modified their AChE so that Pirimicarb can no longer bind to, and inhibit, the enzyme. Observable evidence is also offered by bacterial resistance to antibiotics. These are examples of changes in the population over time (or microevolution). Those who oppose evolution may subsequently say that these are not evidence for the creation of a new species (or macroevolution). But what they fail to realise is that the examples described, such as insecticide resistance in M. persicae, are simply scaled down versions of macroevolution. Given enough time and given a separation in the population, a new species would eventually arise. The beginnings of this were shown in an experiment by Diane Dodd, where fruit flies (Drosophila) were separated into two cages, each supplied with a different food source; one with maltose, the other with starch. After several generations, they were placed into one cage and "maltose flies" were found to mate with other "maltose flies", while "starch flies" mated with other "starch flies".
If evolution is the explanation for the creation of the species today, there should be fossils showing the transition between these species and their ancestors. However, there are not. First of all, not all organisms which have inhabited Earth give rise to a fossil. The formation of a fossil requires very particular conditions, requiring the organism to be buried quickly, and buried in the absence of oxygen and bacteria to minimise decay. It is estimated that less than 5% of all organisms are preserved in this way, and these will not necessarily be perfectly intermediate between forms. Nonetheless, a vast number of transitional fossils have been found (and you may argue that any fossil found is "transitional"). Through these, the evolution of the whale from a tetrapod is well understood and the evolutionary journey leading to the bipedal ape, or human, is now known in great detail.
Lastly, we must mention those who are supporters of God guided evolution. In the Pew research survey carried out last year, 24% of Americans conformed to this ideal. While this may seem like a more legitimate position, and in a way this is the case, it still opposes the fundamentals of science. Science attempts to conform to parsimony as much as possible, that the simplest answer is often the best answer. If a window is left open on a windy day and a vase falls to the floor, it is most parsimonious to say that a gust of wind was the cause, not that an invisible goblin climbed through the window and knocked the vase over. In a similar vein, evolution becomes far more complex by adding God into it. Evolution works perfectly well without a supernatural deity to which there is no evidence of its existence.
As you can see, while there are several arguments that people use to counter evolution, they have very little basis. What is particularly worrying is that their qualms over evolution have been well answered for some time and only require a small amount of research. This is the level of research and logic which they would likely apply to all other areas of their lives. Yet, for evolution, there is a block or perhaps what would be better described as denial.
Why is there this denial? Well, it will come as no surprise that it is likely because of religion. There is a significant positive trend between those who oppose evolution and those who are religious. For many, evolution is incompatible with their faith, either directly or because it tarnishes what they believe in (that humans are a "superior" species). And no matter how logical or how well substantiated an argument for evolution is, it will lose out. This is perhaps due to the precedence of religion in their lives. Years before most children are taught about evolution or have even attended school, they are subjected to religious practice and parents of faith. It is very difficult for them to then reconcile with evolution. In an ideal world, children would be given information about evolution earlier (or at least not indoctrinated with religion as a young child), so they can then make an informed choice. In countries like the US, which are so steeped in religious history, this is not simple to achieve. However, if truth is to win out then something needs to change.
Author Matthew Everatt is currently completing a PhD in invertebrate ecophysiology at the University of Birmingham and is also working in Frontier's Research & Development department. Frontier is an international. nonprofit volunteering NGO, with over 300 dedicated conservation, community development and adventure projects worldwide. To find out more about projects please visit Frontier's blog, Facebook, Twitter, YouTube and Pinterest, or see photos shared by volunteers in the field by searching #frontiervolunteer on Instagram.