“The evolution of life, and the evolutionary origin of mankind, are scientifically established as firmly and completely as any historical event not witnessed by human observers. Any concession to anti-evolutionists, suggesting that there are scientific reasons to doubt the facticity of evolution, would be propagating a plain untruth.”
~ Theodosius Dobzhansky (Christian)
"Whilst on board the Beagle I was quite orthodox, and I remember being heartily laughed at by several of the officers (though themselves orthodox) for quoting the Bible as an unanswerable authority on some point of morality... But I had gradually come by this time, i.e., 1836 to 1839, to see that the Old Testament was no more to be trusted than the sacred book of the Hindoos..."
~ Charles Darwin.
From Charles Darwin: His Life Told in an Autobiographical Chapter, and in a Selected Series of his Published Letters (1902), edited by his son Francis Darwin.
Secondary source: Tom Siegfried in Sciencenews.org January 31, 2009
"Darwin's natural selection redefined the idea of design”.
Introduction
The Theory of Evolution is the foundation for biology and many other scientific and medical fields. As the famous biologist Dobzhansky, a Christian, wrote in 1973, “Nothing in Biology makes sense except in the light of evolution.” Like the scientific theories of Gravity, Cell, Germ, and Relativity, Evolution is both fact and theory and will not be going away. It is that well supported by overwhelming evidence. Even modern medicine is based on it.
When I began medical school after teaching biology at the college level, I was surprised that the professors often referred to evolution more often than my biology textbooks! Why would several of the best medical schools in the world use a famous fish paleontologist (Shubin: Your Inner Fish. University of Chicago) and a cetacean paleontologist (Thewissen - Duke, Northeast Ohio Medical University) to teach human anatomy to medical students? Because we can’t fully understand human anatomy, genetics, disease, and physiology without evolution.
Examples of human clues to our evolutionary past include our recurrent laryngeal nerve that is positioned because we have fish ancestors. We have numerous vestigial ear muscles to hold our pinna - our outer ears - to our heads (see post on unintelligent design, this site) We have thousands of olfactory pseudogenes left over from our much better smelling ancestors. We inherited some of our immune genes from Neanderthals. Tibetans are adapted for high altitude living in part because of a gene called EPAS1 that their ancestors inherited from interbreeding with Denisovans.
So much of what makes a human can’t be understood without evolution (including psychology) that books have been authored detailing it. Our unintelligent designs only make sense under the lens of evolution. For example see books by Lents, Lieberman, Shubin, and Hafer. Of course, that’s just detailing with one species - us. All other animals, plants and fungi also have their evolutionary stories to tell.
The evidence for evolution comes from so many areas of science it would take a small book just to list and discuss all the contributory fields to this grand scientific theory. Instead, I chose to ask what would be my top two best examples for someone that was interested, had limited time, and perhaps little to no biology background. This section will discuss in detail those two examples; whale evolution and shared ERVs among the great apes, which includes us. First, there needs to be some definitional discussion regarding several important terms.
What is Evolution?
The most common definition since the 1940s when Darwin’s idea and genetics merged to form Neo-Darwinism is a change in gene frequency (alleles) in a population over time. Notice that individuals don’t evolve, populations do and if occurring over long periods a new species may arise. Let’s say for example that genes for lighter skin color were advantageous for people living in cold and dark regions (vitamin D is made in our skin from sunlight). Those people who just happen to have lighter skin would do better and have more successful offspring. They would pass their genes on to the next generation at a higher percentage than others. If we were measuring skin color through many generations, the population would develop lighter skinned individuals as a percentage of the population. Forrest Valkai of Internet fame defines evolution simply as a change in heritable characteristics of a population through successive generations. That leaves out the reference to alleles, which of course are what is changing to produce the heritable characteristics. But it's an excellent definition.
The individuals who just happened to inherit better genes for this particular environment would be more “fit” if they produced more successful offspring. Notice that there is no planning - what if the environment happens to change? Then the population characteristics would be under different selection pressures. But what is really changing through generations is the gene frequencies in the population that are producing the physical or behavioral characteristics of individuals. Of course there could be pressures for darker skin also depending on the amount of sunlight or other factors in this example.
People who oppose evolution accept that this can be shown in the lab and in the field but claim these changes are limited. One mouse species evolving into another mouse species is “microevolution” in most lay literature. They are the same “kind” and we never see “macroevolution” they claim - a reptile evolving into a mammal or a fish evolving into an amphibian for example.
I am using the terms here as they are commonly used in public discussions and not necessarily how they are actually defined in biology. Macroevolution is mostly a forensic or historical science, involving changes above the species level. We can accumulate so much evidence in science regarding a conclusion that to deny it would be perverse even if it was not directly observed. Science rarely proves; that’s for some areas of philosophy or mathematics. A good tracker can tell from prints what the species was, which direction it was moving, maybe it’s sex by weight and age, if it was injured, how fast it was moving, when it passed by, etc. without ever seeing the animal.
The same occurs in court cases where a person can be convicted even if the murder weapon (the “how”) is not found. The “what” is not in question. A discussion of why the "what" is first and often independent from the "how" is here at this blog. With evolution, we can know it happened without necessarily seeing all the macro changes. The evidence for evolution is now so overwhelming that to not accept it is perverse. Macroevolution involves more than micro over large time scales. It includes many independent scientific fields and also must include contingencies and random processes (like a rock coming from outer space and ending the reign of the dinosaurs). Macroevolution is the history of life. Laurence Moran has written about his views on micro/macro evolution in his biochemist Sandwalk Blog: https://sandwalk.blogspot.com/2022/10/macroevolution.html
"... evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierachy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts don't go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's in this century, but apples didn't suspend themselves in midair, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered" ~ Stephen Jay Gould in Discover Magazine, May 1981.
An interesting study in marine snails that went from reproducing using eggs to live births has shown that the genes involved indicated gradual steps as Darwin proposed: "Scientists were able to identify 50 genes that are perfectly associated with reproductive mode, as well as estimate the time of their origin. The results showed they accumulated gradually, spreading at different times in the past. This demonstrates that innovation can evolve progressively, rather than in a single evolutionary step."
What is Natural Selection?
This has commonly been defined as the differential reproductive success of individuals within a population. We can demonstrate NS in the lab and in the field. Bacteria developing antibiotic resistance is an example. A bacterial population changing to be more resistant is due to the antibiotic killing off most but leaving some behind to reproduce that just happened to be resistant (nature’s “Left Behind” theater that is real?). In future generations more and more bacteria in this strain will be resistant to that antibiotic. The change in the bacterial population over time is evolution. Again, Forrest Valkai defines natural selection as simply the nonrandom selection of random mutations.
Opponents of evolution by NS claim that NS is not powerful enough no matter how much time to produce significant changes in populations. For example they agree again to microevolution but deny that this mechanism is powerful enough to drive the changes from a shared chimp ancestor to us. Note that NS is just one mechanism - there are others such as genetic drift, horizontal gene transfer and endosymbiosis. For NS to work it needs variation in the population and anti-evolutionists reject known methods to produce significant variation.
Notice that they are arguing against the “how” and not the “what” - the observations and facts that are only explained well by evolution. Mechanisms for evolution are debated all the time in science; the fact of evolution is not. If your house is destroyed and this is not witnessed, one can argue if it was by hurricane, tornado, earthquake, fire, or an angry neighbor but the fact that your house is destroyed is not open to debate. We have so much evidence for evolution that its occurrence is no longer up for debate. There is no controversy about the fact of evolution in science now, just about other issues related to it such as mechanisms (how), abiogenesis, rates, etc.
How We Found That Evolution Is True
Darwin was not the first person to figure out that evolution explained the rich diversity of species, both in the present and past. Many before him had the idea but could not figure out how it may have happened. Watch this short presentation as the idea of evolution unfolded.
Darwin (and Wallace)
In 1837, a year after Darwin returned from his five year voyage on the Beagle, he drew his famous stick figure “I think - transmutation diagram” in his Notebook B that species were not fixed. Darwin had read Lyell’s book about a better way to understand geology while on his voyage (Darwin was primarily trained in geology) and in 1838 read Malthus’s ideas about population growth and why species don’t overpopulate.
The parts for his theory had now all come together. He already knew by then that species could and had changed over time, explaining why many were extinct, fossils and why we see so many that appear related. Mostly because of his wanting to write a book that would be so well documented for his proposed mechanism that his theory could not be dismissed and probably fears about religious backlash, he did not publish his natural selection idea for 20 years but kept doing research. Before marrying Emma in 1839, who was religious, he wrote to her about what his theory would mean: “As soon you realize that one species could evolve into another, the whole structure [foundations of a society established on the Bible] wobbles and collapses”. Later in 1844 Darwin would write to Hooker regarding his ideas, “I have read heaps of agricultural & horticultural books, & have never ceased collecting facts— At last gleams of light have come, & I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable.”
“At last gleams of light have come, & I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable.” ~ Charles Darwin
Darwin’s reasons for delaying publishing his theory of natural selection are debated to this day but his delay was challenged when another scientist, Wallace, discovered natural selection also decades later and shook Darwin to his core when Wallace sent him a draft of natural selection to review for possible publication. Darwin thought he had been “scooped” since he had yet to publish.
Wallace had sent a draft in 1858 to Darwin to review and true to Darwin’s good character instead of demanding that he had the idea long before Wallace - which was true and documented - it was decided that both would present the concept of natural selection together. Their joint presentation to the Linnean Society in London occurred on July 1, 1858. Now Darwin could wait no longer to publish his book, but there was not enough time to write all that he wanted so instead he quickly wrote an “abstract”, what we know as “On The Origin of Species by Natural Selection, or the Preservation of Favored Races in the Struggle for Life” and published it in 1859. See two excellent movie titles about his life in the section Resources.
In Victorian times “races” did not mean what we associate that word with now. Note from the title Darwin’s idea is not about the origin of life and it’s also really not about evolution directly but a mechanism, natural selection, to explain how life unfolded in the past and how to account for the species we see today. At its core God and the supernatural were not needed anymore; only natural processes could explain nature. Of course many religious people including Francis Collins, and the Pope who speaks for over a billion Catholics, have accepted evolution through adopting theistic evolution or evolutionary creationism. Denying evolution is not rational with all the overwhelming experimental and observational evidence available. I will have more to comment on TE/EC later.
A good review:
“Darwin on a Godless Creation: It’s like confessing to a murder.” https://www.scientificamerican.com/article/charles-darwin-confessions/
Two Examples of Evolution, Including "Macroevolution"
I would like to offer only two examples as evidence of evolution. And both of these should satisfy the desire for “macroevolution” evidence. The second is an example of both human evolution and macroevolution. There is overwhelming evidence for evolution from many scientific fields, but let’s just concentrate on these two and drill down on specifics when needed. If you wish to look at some of the many other independent scientific areas that together provide overwhelming evidence for evolution, the University of Berkley has a nice, easy introduction on their site: Lines of Evidence.
Part 1: Whale evolution - The first is whale evolution, because evolving over about 10 million years from an ancestor the size of a raccoon walking around to a toothless baleen blue whale should satisfy as “macroevolution”. If you’ve wondered how scientists know whales evolved I don’t want to tell you, I want to show you the overwhelming evidence so you can see for yourself. The slides usually have citations included so if desired you can go to the original sources. I’ve compiled the material by producing a 3 part series that looks at modern cetaceans, fossil whale ancestors, and DNA evidence with each about 25 minutes in length. Take a look. It will be 90 minutes well spent for all three parts.
If you disagree after watching all 3 parts that whales did not evolve, please write to me as to why. In the comments section of Part 3 I’ve also linked some objections to whale evolution. In most cases critics fail to address the evidence presented but instead put forward a focus only on how all the adaptations arose - how could this have happened? Or what about this instead of addressing the overwhelming evidence we do have.
Part 2: Shared ERVs - this is the best evidence for evolution I’ve seen in 40 years. It’s more technical to explain but well worth your time. I hope you will examine this topic. Others have noticed how powerful it is also and I will be linking sites and short videos for you to evaluate. Also I’ll discuss the common objections put forward and why in my opinion they fail.
Conclusion
If I can convince you that whale evolution must be true (no matter how it happened) then accepting other evolutionary changes should not be overly difficult to accept. If you can understand that 200,000 broken down, randomly inserted retroviral remnants that are found in the exact same locations between chimps and humans can only be explained rationally by a common ancestor then we’ve got our human evolution and macroevolution evidence in one example.
“Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts -- some of them interesting or curious but making no meaningful picture as a whole.”
― Theodosius Grigorievich Dobzhansky
References
The Human Story
Genetics Provide Powerful Evidence of evolution
Whales and Viruses: The Light of Evolution - Episode 1
