Evolution: FAQs

Whether you are a creationist who is growing disillusioned with what you think you know, you are skeptical of the theory of evolution, or you’re simply looking for clarification in some areas, this post may be able to help you. Even among those who readily accept evolution as a fact of nature, misunderstandings are all too common. Here, you will find some basic answers and addresses to more common questions and misunderstandings.

Q: If humans evolved from monkeys and apes, why are there still monkeys and apes?

A: By far the most commonly asked question by those who argue against evolution, the question itself highlights the sheer lack of understanding many people have of evolution. A main issue with this question is that many people are under the false impression that the theory of evolution claims animals such as chimpanzees and rhesus monkeys are our ancestors. This is not the case. The theory of evolution states that these organisms are related to us, and that we share a common ancestor- not that they are our ancestors. Just as how dogs are falsely thought to be evolved from wolves, yet wolves still exist. Though in reality, dogs and wolves are closely related and share a common ancestor.  

Q: At what point in time does an organism become a new species?

A: This is a much more complicated question. A species is defined based on multiple aspects: Appearance, DNA, and reproductive isolation. Members of a same species share a common gene pool that is unique to them because the gene pools of individual species are independently evolving.  There is not necessarily a defined key point in an organism’s history wherein it evolves to become a new one because evolution is an ongoing process, so these different aspects together determine whether an organism should be classified as a new species or not. For example, species endemic to the Hawaiian Islands have ancestors that arrived several million years ago. While when these ancestral species first arrived, they may have been capable of reproduction with other species elsewhere in the world, their geographical isolation on the islands resulted in their adaptation, or evolution to, the specific environment of the islands. Due to the fact that many of these species have adapted and changed so much to fit their new habitat, many of these species on these islands became reproductively isolated from species elsewhere in the word. And hence are classified on their own. So if a group of organisms progresses to the point wherein hybridization is not favored by natural selection, or this group is incapable of reproducing with another species, or this group has a drastically different appearance or ecological function, it will typically be classified as a new, distinct species. 

Q: How can evolution be true when “survival of the fittest” does not make sense? And isn’t this a problematic/eugenics concept anyway?

A: The phrase “survival of the fittest” was coined by philosopher Herbert Spencer, and was often incorporated into the notion of “social Darwinism,” which Darwin himself was not a fan of. While this phrase was added into later versions of Darwin’s The Origins of Species,  it remains the root of many misunderstandings. One of which is the lack of understanding of the biological term “fitness.” Fitness does not merely refer to physical prowess, but is the relative probability that a hereditary characteristic will be favored and therefore reproduced. The fitness may be determined via natural selection by means of competition, or may be determined by environmental factors. Either way, the “fitness” here is not a matter of human preference or conventional ideas of “good genes,” as even mutations that are generally harmful and undesirable may turn out to have a better fitness in specific regions. The most common example among humans being that of hemoglobin A, which is a 4-component molecule composed of two α and two β hemoglobin chains. One gene, HbA codes for the 146 amino acid hemoglobin β chain. However, a mutant allele of HbA, HbS, results in the β chain the amino acid valine in the sixth position rather than the correct glutamic acid. This substitution changes the properties of hemoglobin so that homozygotes with the mutant allele, HbSHbS have a typically fatal form of anemia known as “sickle cell anemia.”  Though it seems natural selection would have eradicated this gene with a seemingly very low fitness, it actually results in heterozygotes, HbAHbS, persisting in greater numbers than the homozygotes without the mutation, HbAHbA. This is because it is thought that these heterozygotes are resistant to malaria, which is particularly severe in regions where these mutations are found. So here we see that we cannot determine based on subjective or conventional ideas of preferred traits whether or not a trait will be beneficial in some way, and thus have a degree of fitness. But the fact that this mutation is in fact concentrated in certain areas, ones where it is beneficial due to circumstances, shows that the idea of fitness is a sound one.

Q: For evolution to be true, the world would have to be millions or even billions of years old. There is no way this is possible! Isn’t the world only around 5,000-12,000 years old? How do we know for sure?

A: One of the primary means of dating artifacts, such as fossils, is through a process known as carbon dating. And while it sounds simple enough, it involves an extensive amount of mathematics. Carbon dating is based on the decay of the radioactive isotope of carbon, 14C. Due to the fact that there is a close constant ratio of 12C, which is naturally more abundant, to 14C, it is used rather than the former specifically because this ratio is maintained until death wherein 14C is no longer replenished. The decay of the overall amount of 14C begins to therefore decay (literally) exponentially, so by determining the amount of 14C remaining in a fossil one can determine how long ago the organism died by the departure of 12C to 14C ratio from the ratio seen in a living organism. The half-life of radioactive isotopes such as 14C are known as the amount of time for the initial amount of the isotope to remain, which is significant because the decay of these isotopes is not logarithmic. The model of the decay of 14C would be: N(t) N0e−0.0001216t.However, it is important to remember than several radioactive isotopes are used in determining ages of fossils, as 14C has a relatively short half-life in comparison to how long organisms overall have existed. Therefore, isotopes with longer half-lives are used to determine the age of presumably older fossils, such as that of 238U (the example I personally used when teaching a class of southern high school students the process of aging fossils). While this may or may not seem mathematically complex at this point, it is certainly not the only math involved. There is also math behind determining not only rate of decay, but the very half-lives themselves. Going back to 238U, using the example provided by Dr. Chabot, if we used a 5.00 mg of pure 238UO2, it would contain 4.41 mg of 238U which decays 100% of the time by alpha emission. If the 5mg were deposited in a thin uniform layer and its alpha activity accounted for, we would obtain a count rate of 16.9 cps with an alpha detection efficiency of 0.315 counts per disintegration (Bq-s). This would then be calculated as follows: A = 1014 cpm/0.315 c d-1 = 3219 dpm = λ N = (ln2/T1/2)(4.41 x 10-3 g/238.03 g/g-atomic weight)(6.022 x 1023 atoms/g-atomic weight). If you solve for T1/2, you get T1/2 = 2.40 x 1015 minutes = 4.57 x 109 years. Overall, faulty arithmetic does exist. But numbers are numbers, and math does not lie. 2+2 will always =4, regardless of if you manage to make a mistake in the process yourself. Math is often a foundation to many scientific concepts, and we know them to be true accordingly. Using these tried-and-true methods of dating, we know for a fact that our own ancestral lineage alone has existed far longer than 5,000-12,000 years. In fact, Earth itself is known to be around at least 4.5 billion years old from the radiometric dating of an old zircon rock in Australia. 

Q: Why trust one random guy? Isn’t evolution all just Darwin’s thing? Creationism is found all over the world and has been for centuries. Certainly thousands of people throughout history are more accurate than this just one man. 

A: While Darwin is often seen as the father, or worse, the “inventor,” of evolution, he is not the only one to truly discover it. Nor is he the only one with early significant contributions to this field. In fact, the first generally realistic theory of evolution was proposed by de Lamark, a French naturalist who lived from 1744 to 1829. Alfred Wallace (1823-1913) is also thought to have discovered it independently from Darwin even though they took up correspondence in 1855, three years before Wallace’s idea of natural selection as a means of explaining evolutionary change. Unlike Darwin, who sought initially to explain the adaptation of organisms to their habitats and the adaption of their physical structure, Wallace intended on actually accounting for the evolution of distinct species, as can be seen in the title alone of his paper “On the Tendency of Varieties to Depart Indefinitely from Original Type.” Other notable people in society at the time of these discoveries also defended the idea of evolution, such as biologist T.H. Huxley. In addition, many others took the idea and modified it into their own theories, applied it to human social life, or went out and obtained further relevant discoveries that would also be published. Founder of the germ-plasm theory, German biologist August Weismann too supported the discovery of natural selection. Others who contributed to an understanding of natural selection are Sewall Wright, an American geneticist, British geneticists R.A Fisher and J.B.S Haldane, Russian-born American Dobzhansky, German-born American zoologist Mayr, Georges Cuvier, American botanist Stebbins, American paleontologist George Simpson, and English zoologist Julian Huxley. When various nations obtained the technologies and scientific abilities to understand ideas such as hereditary, it was no longer a matter of ‘who’ or ‘where.’ Numerous people from different nationalities were able to scientifically support these theories. A lack of ability to explain or rationalize something accurately in the past does not dismiss the findings we have today. Just as it was once thought in the scientifically illiterate and inept past that illnesses were caused by a lack of faith in god or evil spirits, we now know that this is not the case. Although that is not to say that many ancient human societies were not close to hinting at a similar concept, if even for spiritual reasons. This can be seen in the prevalent concept of interconnection of species in many ancestral religions and indigenous communities.  Rest assured, evolution is not just one man’s radical idea. 

Q: I thought evolution was like how a baby deer has spots for camouflage, not like a fish turning into a dinosaur turning into a bird. Which is it? Does this mean deer will turn into bears one day or something??

A: There are two types of evolution: Cladogenesis and anagenesis. The latter is also known as “phyletic evolution” and occurs when lineages of organisms change through generations. Cladogenesis, which is the process by which directly new species arrive, occurs by evolutionary divergence from an ancestral form or diversity as a result of lineage splitting.  ANAGENESIS VS. CLADOGENESIS IMAGE   

The former is determined by looking at the gene pools of a species. In cladogenesis, the original gene pool splits into two or more different gene pools. In anagenesis, one species gradually changes into another on the basis of diversity in characteristics that arose as a result of various adaptions and mutations. Cladogenesis directly forms multiple distinct species, rather than one species gradually becoming a new one. Regardless, a species cannot evolve into a preexisting species. It is quiet possible that given an adequate amount of time and a situation that would make it beneficial, for deer to gradually mutate and change into a species resembling modern-day bears. For example, if one were alive during the Eocene, one might look at pakicetids and remark of evolution “What’s next, pakicetids turning into giant, furless, legless sea mammals?!” without knowing that pakicetids are in fact cetaceans and now known as one of the earliest species giving rise to modern whales. 

Q: How are those evolution tree diagrams made? How do we know they are accurate? Why do some look different? 

A: The tree diagrams used to visually represent evolutionary history of taxa are known as “phylogenies.” The branching of the trees are representative of relative relationships of ancestry or cladogenesis. These trees are also capable of representing anagenesis, or changes that have occurred along each lineage. The anagenetic changes are represented by marks or notches along a specific lineage line leading up to a specific taxon. There are many methods in existence for the creation of phylogenies; different methods exist for different desired interpretations of data. One method that had been frequently used in the past, for example, known as “distance method,” is primarily used with molecular data but may also be used with morphological data as well. The “distance” in the name of this method refers to the distances between two taxa with respect to certain characteristics or to macromolecules like the sequence of nucleotides in RNA or DNA or the sequences of amino acids in proteins. Morphological data may be used by creation of a distance matrix, such as a table using morphological comparisons, which are then transformed into a phylogeny by usually by “cluster analysis.” The smallest distance element in the distance matrix is found and the two taxa or species used are joined at a branching point. The process is again repeated with the next smallest distance and the two next taxa are clustered accordingly. Another method for constructing phylogenies is the “maximum-likelihood method,” which uses statistics to assess the probability of particular mutations. They require a preexisting evolutionary model to be present which makes it then possible to determine the probability of each possible change. All possible phylogenetic trees are considered, and the probabilities for each change are multiplied for each possible phylogeny. The phylogeny that results in the highest probability is determined to be the best tree. This method is typically reserved for smaller numbers of taxa, as with 10 taxa alone there are 3.6 million possible phylogenies. For this method, as well as the distance method, a process known as “bootstrapping” is used to determine the statistical degree of confidence. This is done by random sampling that is repeated hundreds or sometimes thousands of times, and consists of taking samples of the data and removing one data point at random and creating a new tree for the new set of data. Maximum-parsimony is another more common method for making phylogenetic trees. This method intends to reconstruct a tree that requires the fewest number of changes summed along the branches. While this is most likely, it is not always the case because the same changes may occur independently along different branches (some of which may have involved intermediate steps) and therefore sometimes lowers the reliability of this method. The probability of evolutionary changes, even those with the same  number of steps, are not always the same, so this method must take into account any known different probabilities of occurrence.  Typically, ML method and a method known as Bayesian are considered most reliable, while MP is used less often and DM is rather obsolete.

 

Q: If evolution is true it wouldn’t go against my religion. So why do so many churches teach against it if it is a fact?

A: Well, setting aside the fact that religion typically has nothing to do with facts or even the best interests of a person, many religions do not reject the concept. Some are indifferent, some embrace it, and some are skeptical. This goes for many Christian denominations and churches as well. For example, the Catholic Church views evolution as an instrument of God. That yes, God designed and created everything, but that he also is responsible for evolution. The Episcopal church also embraces evolution as a manner in which God can create, and criticizes the idea of intelligent design. The Evangelical Lutheran church states that God may have used evolution in the creation of everything, but seems to have no further interest in the matter one way or another. The truth is that many religions do not find any inherent conflict between their faith and evolution, but that those that do tend to be the loudest thus making it appear that evolution is some form of blasphemy. Surely enough, if you are hardset on following a religion, even Christianity, and your particular path or denomination rejects it, there are many more churches who would be perfectly fine with accepting an evolutionist with open arms. 

 

Q: If humans and apes are so closely related, why don’t they even have an upright posture like we do?

While the means of locomotion for primates is relatively diverse, some of those that are closest related to us actually do have an upright posture. Chimpanzees and gorillas both exhibit a locomotive behavior known as “knuckle-walking.” When observing this motion, one can clearly see that it is done in a way that elevates the upper body, causing a downwards slope following the head down the spine. This is, while not bipedalism, an upright posture. An upright posture can be seen in many other primates as well, albeit not in the form of regular motion as it is with ourselves, gorillas, and chimpanzees. For example, baboons often take advantage of upright posture while eating/foraging, scouting, etc. Another technical form of upright posture is seen when a primate is sitting erect. The reasoning as to why they are not bipedal as we are refers back to reasons as to why we are not classified as members of the same species. Bipedalism is a trait that is, thus far, unique to humans and our direct ancestors. It is unknown as to whether or not true bipedalism was found in the ancestors of chimpanzees.

 

 

[This post will be continually updated as more questions are received and more information is brought to my attention.]

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