Kaylynne M Glover, PhD

What is Evolution?

Probably the biggest reason many dismiss evolution is because most people have no idea what evolution actually is. Many people imagine that evolution means that one individual morphed or somehow became another type of individuals. But that’s not what evolution is. Evolution doesn’t occur when an individual changes –

Evolution occurs as a population changes.

That means that evolution is actually very easy to witness. Biologists monitor populations, and when the genetic makeup of a population varies, evolution is occurring. Evolution as a fact – as something that is observable – has been well accepted for centuries. What was generally unknown is the cause of evolution. What biologists have discovered to date is that there are three main mechanisms that cause evolution.

The first is genetic drift, or just drift. This occurs when a random event changes the population. If a fire rages through a forest, the precise proportion of species left will likely be different after the fire. The random event of the fire caused the genetic change, and we say it evolved.

The second is gene flow, also known as immigration or emigration. Anytime a new individual moves into a population, we have gene flow, and we have evolution. In our fire example, if the fire caused rabbits in the area to flee to a new area, their new home evolved, too.

The third is natural selection, and it is generally considered to be the most impactful mechanism of evolution. Natural selection occurs when nature “selects” the next generation by allowing “fit” individuals to reproduce in greater numbers than less fit individuals. It’s based on a few basic observations:

What happens when you put these four facts together? The most successful individuals have the most offspring, and because those successful traits are usually heritable, the next population will have a greater proportion of “successful” traits. That is natural selection.

At the foundational level, evolution is based on two big ideas. One is that natural processes that we observe around us today have happened in the past and will continue happening. While it is theoretically possible that what we have been observing over thousands of years will change dramatically tomorrow, it isn’t likely, and it doesn’t warrant significant scientific consideration. Science has no reason to presume the laws of nature are about to stop. The consistency of scientific observations has allowed us to harness electricity, to launch satellites, to create atom bombs, and to create medical treatments. It is completely logical to assume that laws have always been acting on earth and will continue to act.

The second big idea is that what we find today was caused by something in the past. In other words, effects have causes. If you step outside in the morning and the ground is muddy, you can logically assume that somehow, water came in contact with the ground last night: it could have been rain, a sprinkler, a busted fire hydrant, or a diverted river. But you are safe in your conclusion that it was caused by water of some kind. Similarly, biologists use this to draw conclusions about what we find. When we find a whale skeleton on top of a mountain, then we can safely conclude that, at one point, that mountain was once land covered by water.

Taking these two premises together, we can conclude that our current observations about how the world works can be extended back in time. If rivers cause erosion now at predictable rates, then we can make estimates as to how fast erosion occurred a million years ago. We can then make predictions about specific events: “If evolution were true, what would we expect to find?” The evidence we have of evolution comes from answers to this question.

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Misconceptions

Many dismiss evolution because they have an inaccurate or incomplete understanding of it. Here you’ll fine just a few of the misconceptions surrounding it. For more information, see our Resources tab.

“Evolution is just a theory.”

In everyday use, the word “theory” is synonymous with an “idea” that someone has about something. However, “theory” means something very different in science, and weigh far heavier than “facts” or even “laws.” Let’s talk about each of the four levels of understanding.

Hypothesis: Hypotheses are predictions, based on facts, as to what will happen in the world. The fact that an apple falls leads to the hypothesis that apples will always fall, and thus allow us to count on apples falling. In science, scientists use hypotheses to make predictions as to what will happen in different controlled circumstances that may be otherwise difficult to determine based on the facts you already have.

For example, taking the fact that you’ve witnessed apples falling, you may hypothesize that apples will always fall. But when you take an apple into space on the International Space Station, apples no longer fall. Is “apples fall” a fact, then? “Apples fall” and “apples float” would appear to contradict.

“Apples fall” is still a fact, and it reveals an important truth of facts: they change based on the circumstances. Facts are limited and are true only in the circumstances in which they were observed. That apples have always fallen on earth says nothing about the behavior of apples anywhere else, or even the behavior of apples tomorrow. Today, apples fall on earth, but they float on the ISS. Both are facts. Hypotheses are stronger pieces of information than facts because they are based on our collective facts.

So, what happens to apples when they’re dropped over water? Or in a ship during freefall?

Theory: Knowing what will happen to apples is one thing; explaining why they happen is another. Scientific theories are the explanations behind the behavior, and they encompass all related facts, hypotheses, and laws. The theory explaining why the law of gravity works the way it does is the Geometric Theory of Gravitation, also known as the Theory of General Relativity. It explains that mass bends space-time, and the greater the mass an object has, the more space-time bends around it. Like a bowling ball on a trampoline, other objects close by are drawn toward the center in a manner proportional to how much mass that bowling ball has. Since the theory of relativity was first proposed in 1915, it has explained anomalies in Mercury’s orbit, unified Newton’s laws with special relativity (what happens when objects are traveling at really high speeds), been supported by gravitational lensing (how objects with really high gravity bend light – for example, why light can’t escape a black hole), and been supported by “gravitational red-shifting” (when you move from an area of strong gravity to an area of weaker gravity, time starts moving faster resulting in a “red-shift” in light).

So yes, evolution is a theory. But it is not “just” a theory. Evolution has as much explanatory power as any other theory, including the germ theory of disease, the theory of electricity, and atomic theory. Dismissing evolution because it is a “theory” is a semantic fallacy.

“There’s no evidence for macroevolution.”

Evolution is often split into two types – “microevolution” and “macroevolution” – and many people will more readily accept microevolution while rejecting macroevolution. Microevolution occurs when there are slight genetic changes occurring in a population over time. It’s most easily observed as bacteria develop resistance to antibiotics.

When many people think of macroevolution, they envision a species morphing into another kind of species: a crocodile turning into a duck, for example. And because we have found no examples of real-life “crocoducks,” some people claim that there are no real “transitional fossils.” But this is erroneous – evolution would never predict anything like a “crocoduck.” Macroevolution does not occur as one species “turns into” another.

Really, microevolution and macroevolution are essentially the same thing with a different time frame. It is logically impossible to accept one without the other.

“If humans evolved from apes, why are there still apes?”

This misconception hinges on a misunderstanding of evolution itself. Scientists don’t say that humans evolved from modern apes. There is no species today that is the ancestor of another species. Your cousin isn’t an ancestor of yours – you share a different common ancestor, one that still might be able to be defined biologically as an “ape”. But apes didn’t “become” humans. Crocodiles didn’t “become” ducks. Your cousin didn’t “become” you. In all cases, they are relatives that are descended from another ancestor. The famous “March of Progress” image depicting a monkey turning into a human doesn’t actually depict evolution, even though it will undoubtedly flood any google image search of “evolution”. These types of images only confuse the issue by presenting evolution as something that it isn’t (which is why I’m not including the image here).

“Evolution = The Big Bang Theory = Abiogenesis (life from nothing).”

Many people believe that these three terms all refer to the same events or processes, but they do not.

• The Big Bang is the theory explaining how our universe first came into existence. Studied primarily by physicists and astrophysicists, it is currently the best explanation we have for how matter first appeared.
• Abiogenesis is the study of how life first appeared on the earth, translating roughly into “creation without life.” It focuses on understanding how the first proteins, nucleic acids, and phospholipids could form, creating the first cellular structures.
• Evolution refers only to the change in existing populations over time.

While these three areas are related, they are distinct, and discussions over evolution should not involve talking points about abiogenesis or the big bang.

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Evidence for Evolution

Entire books have been written detailing only portions of the massive amount of evidence we have for evolution, so this will not be a comprehensive resource, and merely point to a few general areas and provide additional resources for those areas.

Paleontology: Paleontology is the realm of the ever-famous “fossil record” which chronicles the gradual change in species over a very long period of time. While the fossil record is perfect – we don’t have a fossil for every being that has ever existed – we have a lot of fossils that paint a fairly clear – and most importantly, consistent – picture of our past. As we find more fossils, we continually revise our timelines and estimations, but we have yet to find a single fossil “out of place” – an ancient fossil found with fossils from a far more recent strata, or the fossil of a modern-day elephant with the earliest plant species.

What Does the Fossil Record Show? – BioLogos
Fossil record | Definition & Facts | Britannica
Fossil evidence – Understanding Evolution (berkeley.edu)

Biogeography: This is the study of the distribution of living things, usually plants and animals. When we combine biogeography with plate tectonics, we learn about how plants and animals have diversified in ways that support evolution. For example, some kinds of animals are only found in certain areas that have been separated from other areas for a long time. Australia is famous for its unique biodiversity. We find a lot of consistency between the amount of time areas have been separated and the amount of divergence between the species in those areas.

Examples of Biogeographical Proof for Evolution | Sciencing
Biogeography: Wallace and Wegener – Understanding Evolution (berkeley.edu)
How Darwin Developed His Theory – BioLogos

Comparative Anatomy: Comparative anatomy compares the physical structures of different species. Evolution would predict that animals closely related would have similar morphological structures and similar underlying features. For example, humans, cats, whales, and bats are all mammals, and we would expect them all to share similar bone structure. This is, in fact, what we find (see images below), and we call these kinds of structures homologous.

Comparative anatomy | Definition, Examples, & Facts | Britannica
Homologies: Anatomical evidence – Understanding Evolution (berkeley.edu)
Comparative Anatomy – Organisms, Evolutionary, Structures, and Common – JRank Articles
Homologous structures « KaiserScience (wordpress.com)

Comparative Embryology: Similar to comparative anatomy, comparative embryology compares the similarities and differences of embryos of different species. Embryos of different species are remarkably similar, even though their adult forms will look very different. Embryology gives us insight into the evolution of developmental stages as well as the origin of traits.

Evolutionary Embryology – Developmental Biology – NCBI Bookshelf (nih.gov)
What Is Comparative Embryology? (seattlepi.com)
Comparative Embryology – Evidence for Evolution (weebly.com)

Genetics: Genetics is one of the most powerful pieces of evidence for evolution. Genetics is the study of DNA, and DNA codes for proteins that make up an individual. All living organisms rely on DNA, use the same nucleic acids, and use the same processes for reading those genes and turning them into proteins. While genetic changes occur on the small scale (which we use to watch for antibiotic resistance bacteria and to predict changes in the flu virus), we can also use this to trace major changes using “molecular clock” techniques based on known rates of change. Additionally, we can compare the genetic makeup of different species, knowing that, due to reproduction, the more closely related two organisms are, the more similar their DNA will be: closely related family members have nearly identical DNA. We also know that all humans share 99.9% of their DNA, and we share approximately 96% of our DNA with chimpanzees and 92% of our DNA with mice. When you think about it, this makes sense: All three share many key features: we are mammals that give birth to live young after internal copulation and gestation. We grow hair, lactate, and share very similar bone, organ, and muscle structure and function. It’s no surprise that chimps are genetically more similar to us than mice, since their anatomy, intelligence, communication, and social relationships are more similar to us than they are to mice.

The Molecular Clock and Estimating Species Divergence | Learn Science at Scitable (nature.com)
Molecular clocks – Understanding Evolution (berkeley.edu)
Genetic Similarities: Wilson, Sarich, Sibley, and Ahlquist – Understanding Evolution (berkeley.edu)

Speciation Events: Speciation, or the creation of new species, are more common than many initially conceive. A species is defined by its ability to reproduce viable offspring with members of its same species. So when two individuals, who were once part of an interbreeding population, no longer can reproduce, we have speciation. Speciation is the key behind macroevolution – the tiny changes of microevolution accumulate into the incompatibility of macroevolution.

Evolution: Watching Speciation Occur | ScienceBlogs
Observed Instances of Speciation (talkorigins.org)
Cases of Speciation (brown.edu)
Evidence for speciation – Understanding Evolution (berkeley.edu)
Speciation (nationalgeographic.org)

How we use evolution: Evolution is not only supported by the evidence we have, but also by the application of evolutionary principles today. We use it in medicine and agriculture as we combat ever-resistant bacteria and pests. We use it in computer programming to create better and more efficient programs. We use it when we selectively breed domestic animals both for agriculture and for pets (for example, creating specialized breeds of dogs with particular traits). We use it when we manage trophy game populations. The principles behind evolution are so important that they have become the foundation of modern medicine.

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Evolution and Religion

Most who struggle with accepting evolution do so out of religious concerns. I have had many students come to me seeking answers that weigh on their souls: “If evolution is true, what does that mean about God?” “What does that mean about me?” “If I accept evolution, does that mean I’m not a Christian anymore?”

The religious-scientific struggle is not a new one, though it is primarily a problem only for Christians and Muslims. One of the earliest conflicts arose when the Catholic Church opposed heliocentric theory, first proposed by Nicolaus Copernicus in 1543 and later supported by Galileo Galilei, who was sentenced to life under house arrest for his heresy. Claims that the earth wasn’t the center of the universe not only contradicted particular scriptures that seemed to reference an earth-centric system, but also brought to question the relationship between Man and God: “If we are not at the center of His creation, who are we?”

Eventually, most religious people came to terms with heliocentricism, with the Church officially apologizing to Galileo in 1992. Today, we can hardly understand the resistance of scriptural interpretation against scientific fact. Most Christians today find no difficulty accepting their role as Children of God, even if humans aren’t at the literal physical center of His creation. They can accept that scripture written thousands of years ago, having undergone hundreds of translations, written for people with no understanding of science, can still be true without being factual.

Christianity and Islam are facing similar struggles today, trying to understand evolution and the implications it may have in their relationship to God: “Who are we if we evolved?” And this is no small question to answer.

Reconciling these is difficult because the beliefs being taught by religion is based on the accepted science of the day. There was no reason to reject geocentricism before Capernicus, and doctrine reflected the certainty of the Truth of Heliocentrism. When that Truth was questioned, the bedrock of their faith was questioned. The mistake they made was in tying their religion to their current understanding of science, a doomed relationship when our understanding of science is only limited by time, technology, and invention.

Today, few Priests, Pastors, Ministers, Bishops, and Imams teach that mankind’s relationship to God is based on geocentricism, but evolution causes many to ask the same question, and perhaps a few more: “If evolution is true, what does that mean about God?” “What does that mean about me?” “If we are not at the center of His creation, who are we?” “If I accept evolution, does that mean I’m not a Christian anymore?”

While I cannot speak for all, and certainly not for God, perhaps I can help answer some of these questions.

“If evolution is true, what does that mean about God?”

It means that God is a scientist. It means that He operates through laws that He set down eons ago. It means that He created a Universe that managed to get everything right in order to create humanity – which demonstrates far more skill than someone who could just snap their fingers and bring someone into existence. And it means that studying science can only teach you more about God.

“What does that mean about me?”

It means that God spent 4.6 billion years to get you here, instead of thinking you into existence. And I don’t know about you, but it is only those things that I take great care in creating that I consider special. To me, the idea of God using evolution is far more indicative of a special creation than a 6-day one.

“If we are not at the center of His creation, who are we?”

You are being of great potential. Your ancestors not only include all of the animals that existed before you, but also includes the God who created you. And it means that your descendants have greater potential still.

“If I accept evolution, does that mean I’m not a Christian?”

Some may tell you that accepting evolution turns your back on God. But I think that denying the evidence of the world He created is turning your back on God. When someone make assumptions about what God did and didn’t do, they are constraining their own understanding of who He is. You can never understand what you cannot conceive, and you can never truly come to understand God unless you’re willing to accept that He might have done things differently than you imagined.

That one can accept evolution and retain their relationship with God is evidenced in the many religious organizations that have issued statements in support of their adherents accepting it. While not comprehensive, the National Center for Science Education (NCSE) provides a list, and many other religious organizations have issued similar statements. If you are struggling with this, I encourage you to review some of the items listed on the Resources tab.

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Resources

Below you will find several resources that center on the relationship between science and religion, and others are resources on evolution itself. Many are books because the topic can rarely be adequately covered in a single link. I do not necessarily endorse all of the content or conclusions in these books, though I do believe they help provide a useful perspective for those seeking answers to these personal questions.

Media Center | National Center for Science Education (ncse.ngo)
The Christian Man’s Evolution: How Darwinism and Faith Can Coexist – Scientific American
Frequently Asked Questions | Science, Evolution, and Creationism | The National Academies Press

Books:

Finding Darwin’s God: A Scientist’s Search for Common Ground Between God and Evolution by Kenneth R. Miller | Goodreads
Why Evolution Is True by Jerry A. Coyne | Goodreads
The Language of God: A Scientist Presents Evidence for Belief by Francis S. Collins | Goodreads
Only a Theory: Evolution and the Battle for America’s Soul by Kenneth R. Miller | Goodreads
Rocks of Ages: Science and Religion in the Fullness of Life by Stephen Jay Gould | Goodreads
Evolution vs Creationism (2nd, 08) by Scott, Eugenie C [Hardcover (2008)] by Scot | Goodreads
Navigating Genesis: A Scientist’s Journey through Genesis 1-11 by Hugh Ross | Goodreads
Adam and the Genome: Reading Scripture after Genetic Science by Scot McKnight | Goodreads
How I Changed My Mind About Evolution: Evangelicals Reflect on Faith and Science by Kathryn Applegate | Goodreads
I Love Jesus & I Accept Evolution by Denis O. Lamoureux | Goodreads

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