Big Misconceptions of Evolution.

January 25, 2009

  • Microevolution occurs; Macroevolution doesn’t. This is a fallacious claim. Microevolution is evolution which occurs below the species level, i.e. variation within a population. Macroevolution occurs at and above the species level, i.e. the formation of new species and clades. Although most Biologists regard the distinction between the two to be non-existent, the mechanisms which lead to both are one and the same; gradual, cumulative selection. Macroevolution is simply an accumulation of microevolution. If a macroevolutionary change can be described as going from the bottom to the top of a staircase, then the microevolutionary steps constitute the individual stairs. However, it is also possible for macroevolution to occur in larger ‘spurts’, through mutations which occur in the genes involved in the development of an organism (e.g. Hox genes, which are involved in patterning the body axes, giving rise to morphology); for example, by changing the sequence of a transcription factor (a switch for turning genes on or off) for these genes, the body morphology can be radically changed. Speciation of many organisms has also been directly observed, ranging from bacteria to drosophila. Macroevolution is a gradual accumulation of microevolutionary steps, but may also occur in larger rare bursts, for example through changes in the sequence or expression of genes involved in the development of an organism (e.g. Hox genes).
  • Evolution is pure chance. This statement shows a huge misunderstanding of evolution. At its most basic fundamental level, evolution has two basic components: genetic mutation, and natural selection. Genetic mutations are random, and occur due to errors during DNA replication, chemical mutagens, radiation, and other factors and processes. These mutations give rise to the diversity that we see amongst genotypes, through to species variability. However, what decides whether mutations are beneficial or harmful is natural selection.

    Natural selection is the passive process by which any allele that confers an advantage on an individual’s reproductive fitness will increase in frequency within a population, whereas any allele that has a detrimental effect will decrease in frequency. Therefore, since reproductive fitness involves competing against all other individuals, where only the most reproductively fit ones pass on their genes, natural selection is a non-random process. This is where the idea of chance disappears. Natural selection is the complete opposite to chance. Any slight modification that impacts upon an individual’s reproductive fitness will be under selection. Evolution is not pure chance. Only genetic mutations are random; natural selection is a gradual, cumulative, nonrandom process.

  • Evolution does not produce new ‘information’. This could not be further from the truth. Information here is defined as new DNA sequences which code for new traits. There are many ways in which new information is created, the main being through genetic mutation, whereby the DNA sequence of a gene is changed, which can produce a new variant of the gene (allele). Also, the ‘amount of information’ within the genome can be increased (i.e. increasing the number of genes and variants of those genes). The most common way for this to occur is via gene duplication and divergence.
    This illustration shows a gene that has duplicated. (Figure taken from https://i1.wp.com/www.wikidoc.org/images/7/72/Gene-duplication.png).

    This illustration shows a gene that has duplicated. (Figure taken from http://www.wikidoc.org/images/7/72/Gene-duplication.png).

    Genes can duplicate through errors in the replication of chromosomes, or even whole genomes, or during sexual reproduction when homologous recombinational events are uneven, giving rise to extra DNA sequences which may contain the whole of an extra copy of a gene. The organism which inherits this extra copy will now have two copies of the same gene with the same function. Thus, one copy is available to freely mutate and diverge, whilst the other retains its original function, without affecting the fitness of the individuals who carry it. Over time, it may form a new allele (variant of the same gene), which will provide a new function. If this allele is beneficial to the individual’s survival and reproduction, then it will be inherited by future generations and will spread through the population. Thus, this new piece of ‘information’ will be incorporated into the genomes of the population. New traits however do not come exclusively through increasing number of genes or mutations in genes themselves; the changes in interactions of the gene products themselves, and the expression patterns of genes, all give rise to new combinations of traits which can be utilised by the organism. Genetic mutations can produce ‘new information’, which can be subject to selection. gene duplications and divergence can increase the ‘amount of information’ in a genome. However, there are other processes that also create new ‘information’ in the genome.

  • Modern day animals evolving into other modern day animals. Species do not evolve into other species. In some circumstances, integration of two species can occur if there are no reproductive barriers, but this is different to one species becoming exactly like another. However, organisms can evolve structures and morphological characteristics that are similar to those found in other organisms residing in similar environments (a process known as convergent evolution). The eye is an example of this, and has evolved many times independantly. All the animals that we observe around us are at the end of the branches of the tree of life. These end branches do not evolve into one another. Just like anybody who has a sibling will share a common ancestor with them (father or mother), and also with cousins (grandparents). Modern day animals do not evolve into other modern day animals. All modern day animals are terminal branches of the tree of life, and do not evolve into each other.

  • Species never evolve into other ‘kinds’; dogs remain dogs, cats remain cats. This misconception originates from the fallacy of classifications of organisms. Humans, more specifically, taxonomists, classify organisms according to certain criteria. As observers of modern day life, we can name individual species according to our own standards, i.e. a dog as a dog, and a cat as a cat. The same goes for naming groups of animals. A whale is a modern day animal which lives in the sea. We classify it as a mammal, because we can trace its evolutionary history back to a land mammal. However, we can also point out that we are all descendants of fish, because the first land dwelling creatures originated in the sea. Some fish gained the ability to spend time on land as well as continue living in the sea, and these fish were known as amphibians. Those amphibians gave rise to modern day amphibians, and reptiles, which eventually gave rise to modern day reptiles, and mammals. So technically, we could classify all mammals as reptiles, and all reptiles as amphibians, and so on, until we classify everything as fish. But we don’t, as this would not help us one bit in describing groups of species, hence we use a system which allows us to do so.  It can take millions of years for many species to evolve into new species, and since we are not around to directly observe all events of speciation, we have to infer them from the fossil record and phylogenetic analyses. After inferences have been made, we may name each separate individual species that forms part of a lineage leading up to a modern day animal for our own purposes. Each individual species is a branch which branches off from another branch, and so on, until you reach a terminal branch, which would either represent an extinct species, or a modern day animal. However, taking the evolutionary lineage of the dog as an example, a dog can be called a wolf,  since it evolved from the gray wolf; it is taxonomists who give names to members of species from different places in time of a specific lineage, which have descended with modification. Speciation is like a rainbow spectrum; you can observe different individual colours, but when you examine them closely, they are all a smooth continuation of one another, with no distinct boundary; humans classify individual colours according to our own criteria, however in reality, violet is just a continuation of indigo, which is just a continuation of blue, which is just a continuation of green, etc. All species are related, and share common ancestors, ultimately sharing a single ancestor or population from which all species are descended. Species are named according to criteria used by Taxonomists, however, all species are really just a branch of the tree of life. A species may be named by branch or lineage, but we name modern day animals according to our standards, and also to help identify and describe particular species.

  • If humans evolved from monkeys, why are there still monkeys around? A very common misconception which shows two errors of misunderstanding. The first is simple; humans did not evolve from monkeys, we simply share a common ancestor with them. This can be confusing when the term ape is used, as the layperson usually uses the term interchangeably with monkey; since we evolved from, and are apes, the layperson wrongly assumes that this must mean we evolved from monkeys. This is of course incorrect, as ape is the name given to the clade, or group of related organisms, which includes the ancestors, and living members of gorillas, chimpanzees, orangutans, and of course, us humans too. We four form a clade known as the Great Apes; another clade, known as the lesser apes, includes gibbons. These clades are part of a bigger group, known as an order, called primates. Primates also include monkeys, and our relationship to them can be traced to a common ancestor around 40 million years ago.
    This tree shows the relationships between apes and other primates, including monkeys, and also the relationships between the apes themselves.

    This tree shows the relationships between apes and other primates, including monkeys, and also the relationships between the apes themselves (Figure taken from http://www.greatapetrust.org/images/primates/primates_tree.gif).

    Monkeys are often confused with chimpanzees, and thus a double misconception arises when people mistakingly assume humans evolved from chimpanzees, and then slip up again to assume that chimpanzees and monkeys are one and the same. A second fallacy assumes that if one species evolves from another, it should somehow replace the original species. This is false. Species are broadly defined as separate populations which cannot successfully interbreed with one another to produce reproductively viable offspring. Speciation, the process of the development of new species, can occur in many ways, but one key stipulation is that there is reproductive isolation between the two populations that are eventually going to become separate species. This means that no interbreeding can take place between the two, so that over time, an accumulation of many individual differences will no longer support viable reproduction. The most common way for reproductive isolation to occur is if there are geographical barriers separating two populations, or if some members of the original population migrate away, to form a separate population. When this occurs, these separated populations may have different ecological requirements, so replacement of the older species does not necessarily happen. Of course, replacements can occur if both species are reunited in the same niche (environment); if there is a competition for the same resources between both species, and one successfully outcompetes the other, then the unsuccessful species will become extinct. But in the case of humans and other apes, this was not the case, and since each species coexisted with each other successfully, there was no reason for any ‘replacement’ to occur. Humans did not evolve from monkeys; we share a common ancestor with them. We are apes and have evolved from earlier lineages of apes. When speciation occurs, a new species does not necessarily replace the species from which it is descended.

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8 Responses to “Big Misconceptions of Evolution.”

  1. dawkinsrottweiler said

    Thank you to a friend for advice on the structure of posts, as well as the idea of summaries at the end of each point.

  2. […] I draw your attention to Ashwin Khanna’s blog. Ashwin, a fellow medic and studying geneticist at Manchester University has compiled a concise and rather complete look at the big misconceptions of evolution, which I urge to read, here. […]

  3. dalyness said

    A very concise and evidence-based look at evolution and the big misconceptions that surround it. I urge people to read and take heed of such articles, you won’t regret it.

  4. heardofgod said

    So basically what your saying is, “If your going to make comments about the philosophy of evolution, get it right.” That is so cute.

    The only thing that seems to be evolving is the philosophy of evolution itself.

    Maybe if there was some sort of starting point of truth that evolution could springboard off of. you know, like evidence that can be observed. As of yet, I’ve seen pointing, laughing, assertions, and the occasional “Christians are stupid” elitist, dogmatic. He he he. It’s all smoke and lights for an entertaining play. At least I’m entertained. I like tap dancing.

    Peace Broseph,
    Keep the dream alive,
    Sam

  5. dawkinsrottweiler said

    I shall be posting a long piece for the evidences for Evolution very soon indeed. However, until then, it would be useful to you if you just picked up and read a book on Genetics and Evolution. It seems to me as if you are so afraid of the truth of Evolution.

  6. dalyness said

    If you deny evolution, you do realise that every single university in the United Kingdom and a vast majority of Universities in the world disagree with you Sam. Not that that ‘really’ matters, although, let me justify; these are Universities with hundreds of years worth of experience, academia and intellect behind them, not to mention hard, concrete evidence to support what they teach. You never replied to the comment I left for you on my blog Sam, with the evidence for evolution- I am hoping you do. I’m not pointing and laughing at religious people in the slightest- I am sincerely rendered speechless when I hear some of the views expressed to me by some people of faith whenever they defy all logic and contravene all evidence. Furthermore, all I see yourself doing is writing in facetious and sarcastic rhetoric.

    The fact of the matter is, the earth is no where near 6000 years old- we have mastered the use of dating (Carbon etc). Humans most definitely evolved from early primates and there is plently of evidence to support this (Natural History Museum, Fossils etc). Moreover even if there was only one single piece of evidence to support evolution- it would be one more than any creationist will ever possess to prove creationism happened.

  7. heardofgod said

    Dawkinsrottweiler, afraid of what? Are you even reading? Evolution has not even given me something to be afraid of. A little proof would go a long way here….

    I bet the evidences you post will be easily interpreted another way. Can I make a request? Can it be evidences that cannot be refuted, like why the fossil record is missing a few million transitional forms. Genetics can’t solve that. However, once you do solve that then we can start interpreting evidences from a starting point that evolution might be true. Until then,

    Keep the dream alive.
    Sam

  8. David said

    Evidence that cannot be interpreted a different way… it may be a good starting-point for you to lay out how indeed you (or others?) may interpret such evidence. The evidence that is in hundreds of museums, archives, research labs… it would be interesting how one can contradict such a vast wealth of evidence… and this is evidence, it’s not pie-in-the-sky philosophy- these are brute facts with real, physical fossils! We do share a common lineage with early primates and a million-and-one things besides…. which, might I highlight, we have brought forward evidence for. You have said that it is “interpretation”… I’d like to hear your interpretation of it. Precisely.

    “Missing a few million transitional forms”? What a ghastly misconception! I almost wish to say “touché” and ask for the millions of years, nay, few billions(!) that the creationst account is missing. I think the author of the blog addresses the “Missing Transitional Forms” argument in his latest post.. he does it justice far better than I would at this moment… do read it.

    Kindest Regards
    David

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