Depending on where you live, evolution can be seen as a controversial subject. But it shouldn’t be. Here’s why.

What is Evolution?

Evolution is a very simple idea: Species change over time due to changes in their gene pool. Sometimes these changes lead to new species.

That’s all.

It’s pretty easy to see why this idea makes sense if you look at living animals. You can plainly see that horses and donkeys are related. It’s patently obvious that cats of all sizes are related to each other. Mice, rats, and shrews share plenty of similarities. Even different insects share commonalities. Much like we are related to our siblings, cousins, parents, and grandparents, almost all animals seem to be related to each other.

You can also look at fossils to see more proof that this happens. Most of the species that appear in fossils are not alive today. But there are a handful of fossils that bear striking similarities to current species. Shark fossils haven’t changed that much at all. Modern birds share a lot of similarities with velociraptors. Even insect fossils (preserved in amber) look very similar.


Naturalists and biologists have known for centuries about these things. The question was never whether evolution was real. The question was HOW evolution worked. What was the fundamental mechanism that made evolution possible?


We begin our explanation of HOW evolution works with an example of what people thought before Darwin’s Theory of Natural Selection. The first fully-fleshed out idea came from a chap named Jean-Baptiste Lamarck. Lamarck explained that parents would pass their acquired traits onto their children. These acquired traits could eventually lead to a new species of animal if one group was different enough.

Say for example, a horse noticed fruit on a tree. It might stretch and strain its neck to reach the fruit. If the horse kept doing this day after day, it might stretch its neck just enough to reach the fruit. Under Lamarck’s hypothesis, this horse would get a longer neck. Then, when the horse has children, they would have slightly longer necks too. If those children also saw fruit in the tree, and stretched their necks to reach it, their children would have even longer necks. Continue this process over several generations, and Lamarck proposed that you would have a giraffe, with its incredibly long neck.

Since it was the first hypothesis of its kind, many people latched onto Lamarckism. But there’s quite a few problems with it:

  • It doesn’t really explain the evolution of plants or microbes.
  • It doesn’t fit with our understanding of how genes are inherited.
  • If Lamarckism were true, we would expect to see species with missing limbs, which we don’t.
  • It doesn’t explain why species go extinct.
  • It suggests that evolution trends towards complexity, but fails to explain why there are still microbes.

Luckily, Lamarckism wouldn’t have a long time in the spotlight before a young upstart named Charles Darwin came along.

Natural Selection

We could do a whole article about Darwin’s trip on the HMS Beagle and his discoveries, but that’s another article for another time. Instead, we want to focus on Darwin’s Theory of Natural Selection.

Young Charles Darwin was interested in the writings of Thomas Malthus. Malthus wasn’t a biologist. He was an economist. Malthus believed that food and resources were finite, and scarcity was a defining factor of life. When food and resources were plentiful, people would reproduce in great numbers, and generally have little to worry about. But when food and resources were scarce, Malthus argued, conditions would get worse until war or famine broke out, causing a great amount of death. Once a large number of people died, Malthus postulated, resources would become plentiful again and the cycle would reset.

Darwin read Malthus’ ideas and applied them to biology. If one assumes that the natural world is scarce on food and resources, how would that affect living organisms? Logically, some of them would have to die, just like Malthus’ believed.

But what about the organisms that survived? The ones that lived? Well, they would still need to have offspring in order to continue the species.

This is where the Theory of Natural Selection begins. Natural Selection assumes a few things:

  1. We have heritable differences. (Genetic variation)
  2. Some individual organisms are better suited for their environment (often shortened to “Fitness”).
  3. Organisms must compete for limited resources. (Competition)
  4. Organisms must reproduce to continue the species (Sex).
  5. Some kind of selective pressure (IE Food scarcity).

In other words, the organisms that are the best suited to compete (the most “fit”) will also have the most offspring. In turn, the most “fit” of these offspring will have the most offspring. And so on and so on. As another scientist (Herbert Spencer) put it, “Survival of the fittest.”

Over time, natural selection will lead to permanent changes in a species genes. These changes are evolution.

Side Note: “Just a Theory”

One of the more common arguments against evolution hinges on the concept that the Theory of Natural Selection is “just a theory.” In regular English, a “theory” is more like a hypothesis. It’s a guess. But in science, theories are much more than hypotheses. They are explanations of why things happen based on evidence, complete with predictions for what will happen under certain circumstances.

In this way, a scientific theory is actually stronger than a scientific law. Scientific laws only contain rules of thumb, but they don’t always work in every scenario. In order to be considered a scientific theory, a postulate must have the following characteristics:

  • Consistently makes accurate predictions that could be proven wrong (falsifiable).
  • It is supported by many different lines of evidence, not just one.
  • Its explanations work for past experiments, and it is more accurate and precise than previous theories.

Artificial Selection

We don’t just have to take Darwin’s word for it. We can test natural selection via artificial selection. Like any good laboratory test, we can isolate the variables. We determine what the evolutionary pressures are and the environment. In one example, Harvard Medical set up an experimental protocol testing natural selection with antibiotics.

Soviet Russia also tried a similar experiment. Dmitry Konstantinovich Belyayev was a Soviet scientist who was interested in evolution. He wanted to domesticate foxes through breeding. So he did. He captured small populations of wild silver foxes and crossbred them. He was looking for 2 characteristics in the silver foxes that he was breeding:

  1. They weren’t scared of humans.
  2. They weren’t aggressive towards humans.

In a few generations of breeding, Dmitry produced domesticated foxes. It took about 20 generations to reliably breed them, but a few appeared around the 6th or 7th generation. These foxes are friendly towards humans, and are actually available for sale today. You can buy Siberian foxes online, but there all sorts of legal restrictions on exporting and importing.

One interesting side note about these foxes is that while they were only being bred to reduce aggression and fear, they started to look and behave more like dogs and puppies:

  • They got fluffier tails
  • They started to bark and wag their tails like dogs
  • They got spotted/mottled fur
  • They were able to reproduce more frequently.
  • They could learn and follow simple commands.
  • They retained youthful appearances into adulthood.

And just like we’ve domesticated animals, we’ve also domesticated plants. Watermelon used to look… very different:

Notice a certain fruit in the lower right? Yep, that’s watermelon. This painting is from the 1600s.

And watermelon’s an easy example. Some of our crops have wild counterparts, and they’re very different.

See the difference?

These species have had permanent genetic changes as a result of our actions. We have made them evolve because of the selection pressures that we placed upon them.

Grandeur in this View of Life

Evolution is the permanent genetic change of a species over time. All living things must adapt to meet changes in their environment or perish. As a result, only those that can survive and reproduce are able to pass on their genes. This logic is elegant in its simplicity, and grandiose in its scope. To quote Charles Darwin from “On the Origin of Species,”

It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. […] There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

– Charles Darwin, “On the Origin of Species”

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18 thoughts on “The Basics of Evolution: It Really Shouldn’t Be Controversial

  1. Of course, evolution is real and proven. The world’s best scientists have been studying it for over 100 yrs. Creationism is based on the Bible, which is a book of ncient myths, and has no scientific value whatsoever. Teaching Creationism in schools is against the principle of the separation of church and state as set in the United States Constitution.

  2. I’m impressed by the domestication
    of silver foxes. I was aware of it some
    40 years ago when I married and for
    as long I tried to domesticate my wife
    without success.

    Should she breed with another
    silver fox? I thought I was top fox!
    What am I doing wrong?
    No need to respond to this
    unless you have an answer.

    1. I’d posit that you aren’t doing anything wrong, Alex. Instead, it appears that your subject is better suited for a different environment (please see assumption #2, “Fitness,” in Natural Selection, above). [;-) all in good fun, Alex]

  3. Natural selection or adaptation happens everywhere in nature, but it’s always within the limits set by the genetic code, based on the information it already contains. There is no instance of brand new genetic information being added into the genetic code, which is required for molecules-to-man evolution to occur.

    1. Hi Patti!

      Actually, new genetic information can appear all the time in the form of mutations. I will cover this in a future blog post, but mutations can introduce new genes, duplicate old ones (allowing for additional modifications), delete or invalidate existing ones, or even cause completely novel genes to form. If you’d like a quick idea of how DNA can do some really weird stuff, I recommend looking up transposons.

      1. Hunter, while it is certainly fascinating that transposons have the potential to not be destructive (see medaka fish), the caveat given in the example i read on a article found a positive increase in heritable pigmentation possibilities only in a highly inbred line of these organisms (not exactly a glowing recommendation for a means by which a species might evolve!)

        The main example given in that same article admitted the reality that the L1 transposon was actually present in colon cancer cells…not exactly a positive example of new information being inserted into a genome for the purpose of its variation to increase potential for evolution.

        Possibilities are interesting, but it’s important to consider reasonability as well.

        Full disclosure: I simply did a quick google search of your recommendation and clicked on the first reputable scientific agency (not Wikipedia) who could “dumb down” the concept for a biology major who’s been a bit removed from his undergrad.

        1. Hi Daniel!

          You’re right! Most mutations will either be neutral or negative. It’s rare for a new one to be beneficial in some way (I’ve heard estimates of less than 1% of all mutations), but it does happen now and then. I was using transposons as an example to illustrate how our genetics are much more fluid than they might seem, and how sometimes genes can appear out of seemingly nowhere. If you’re more interested in researching different topics on the subject, I recommend a few of the following:

          * Gene Duplication
          * Horizontal Gene Transfer (also called Lateral Gene Transfer)
          * Molecular Clock (specifically how it can vary)

  4. Yeah, there are working scientists who aren’t part of the ‘big science’ (Higher Education, Grants, Books, National Geographic, and etc.) who have legitimate differences with the Monkey to Man — they don’t ‘buy it’ either. Man’s body has same elements as ground, chromosomes (after their kind), species, and how bones and rocks and sediments are determined and with what assumptions.

    I’ve heard some very solid arguments for other explanations about life on earth. From scientists.

    1. Hi Mr./Mrs. Hills!

      I would love to meet the “Big Science” you speak of! I’ve been in scientific institutions since college, and I’ve never seen what you describe. The money in science mostly comes from corporations (typically chemical corporations such as Bayer or Dow) or government grants.

      Yes, our bodies DO have the same elements as the ground does. Carbon, hydrogen, oxygen, nitrogen, phosphorus, and more.

      Evolution never attempts to explain the origin of life. It only deals with what happens after life began.

  5. The above are old arguments scarcely worth repeating. At Michigan State Lenski and associates sequenced the entire genomes of two representative cultures of two bacteria after 1000, 1599, 2500, 5000, 10,000. 20,000, 30,000 40,000 and 50,000 generations.
    Bottom line (From Darwin Devolves by Behe): “After fifty thousand generations of the most detailed, definitive evolution experiment ever conducted, after so much improvement of the growth rate that descendant cells have revived ancestors in the dust, after relentless mutation and selection, it’s very likely that all of the identified beneficial mutations worked by degrading or outright breaking the respective ancestor genes. And the havoc wreaked by random mutation had been frozen in place by natural selection”.
    In 2016 the Royal Society of London called a meeting to assess why the Darwinian theory was rapidly losing traction in the scientific community. The result: There was no plausible defense of the theory in light of ongoing scientific research.

  6. Evolution within species is well documented. Genetic coding has adaptation built into it, as researchers continue to find. – However, the rapid growth beyond single cell animals in the Cambrian period does not support Darwin. Little to no relationships between species that survived prove that. A frog did not become a bird and a rat did not become a deer. Just sayin! – DNA is pure coding language, beyond what we can imagine or produce today. It is “1’s and 0’s” at the highest level. Random “Evolution” does not account for this or the time frame to produce the variable proteins needed for millions of new species and life forms. Our genetics, as humans, just trace one specific line of the Cambrian growth explosion. So let’s understand that beyond our personal genetic history, we have way more to learn than Darwinian Theory.

    1. Hi Mike!

      I agree that a frog did not become a bird, nor did a rat become a deer. That’s because they share a common ancestor that diverged at some point in the past. There are many means of speciation (allopatric speciation, sympatric speciation, polyploidy, etc), and I highly recommend checking them out.

      DNA isn’t quite like binary. Because DNA is a molecule, it can be modified chemically AND physically. There’s an entire line of research around this called epigenetics. In addition, the environment can alter the expression of given genes.

  7. I think that the ‘theory’ part of Evolution is the part that attempts to explain the unobservable and so far unreplicable (I’m not sure this is a word…) past. Science is the observation of the natural world. Because Evolution, as an explanation of the development of new species, hinges on the passing of millions/billions of years, I think that it’s fair to present it as a potential explanation for life on Earth today, rather than as undeniable fact. It might be different if we had a complete and unbroken fossil record to prove the evolution between species, but even then it would be an explanation of the past based on the conditions of the present.

    In my opinion, natural selection and the adaptation of genes(both observable) are not inseparable from the theory of Evolution(again, as an explanation for different species). A scientist can be as intelligent and make just as many discoveries whether he or she begins with the premise that life on Earth was intelligently designed or that it came about after an indeterminable amount of time, trial, error, and survival. I don’t think that natural selection should be controversial, but ‘Evolution’ has become a dividing word because people use it to put down those who think differently than them. To say I believe in intelligent design is not to say that what I don’t believe or study science, and that’s where I think it can become divisive and ‘controversial.’

    Thank you for your work in writing this article, and for your thoughtful responses.

    1. Hi Abby!

      Thanks for your response. While it is possible that there might be an intelligent designer (after all, who’s to say alien life didn’t interfere?), the trouble is that there is a substantial lack of evidence for this theory. Many of the arguments for intelligent design hinge on deductive logic rather than abductive logic. Deductive logic (or top-down logic) relies on abstract reasoning to come up with an explanation rather than experimental evidence. Abductive logic depends on using experimental evidence to come up with with an explanation.

      Take for example, the idea of irreducible complexity. It’s also known as the watchmaker argument. It stems from the fact that we, as humans, can create complex things. We observe that there are complex things in nature, and assume that a being as smart as us had to create it. But this is abstract reasoning — it’s not based on any evidence of another being manipulating the complex object.

      However, and I will concede this, absence of evidence is not evidence of absence. But simply put, science only works on what we can demonstrate.

  8. I think this poem says it all
    Darwin’s Mistake
    Three monkeys sat in a tree.
    Discussing things as they’re said to be.
    Said one to the others, “Now listen, you two,
    There ‘s a certain rumor can’t be true,
    That Man descended from our noble race,
    That very idea is a disgrace.
    No monkey ever deserted his wife.
    Straved her babies or ruined her life.
    And you’ve never known a mother monk
    to leave her babies with others to bunk,
    or pass them on from to another
    ‘Til they scarcely know who is their mother;
    And another thing you’ll never see —
    A monk build a fence around a cocount tree
    And let the cocount go to waste,
    Forbidding all other monks a taste.
    If I’d put a fence around this tree,
    Starvation would force you to steal from me.
    Here’s another thing a monk won’t do,
    Go out night and get in a stew,
    use a gun or club or knife
    to take another monkey’s life.
    Yes, Man descended, the ornery cuss —
    But, brother, he didn’t descend from us.”

    1. As far as I know, no new theories. The current theory is just that natural selection picked one, and all the species rolled with it (or the other ones got outcompeted). I have heard some suggestions that some reactions work better with certain enantiomers, but that’s about the extent of what I know.

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