This blog post was developed in conjunction with Professor O.R. Pagan from the University of West Chester Pennsylvania in light of some common cultural misunderstandings we’ve observed about the subject of evolution.
There are two deeply misunderstood and unfairly maligned terms in science: the words “evolution” and “theory”.
It is important to distinguish between the term “theory” in a conversational sense and the word “Theory” as it is used in science. Many people confuse the two and this shows a fundamental misunderstanding about the scientific process.
A “theory” (all lowercase) is essentially a guess or an opinion, as in “this is what I think.” On the other hand, a “Theory” (capitalized) in the scientific sense is a model that organizes a wide variety of phenomena, integrating them in a logical way which has little to do with personal opinions. In this way, a Theory is capable of explaining additional observations and most importantly, makes predictions. Over time, these additional observations are used to modify the Theory and in some cases, even change it entirely.
It is dangerous to confuse “facts” with “Theories.” For example, consider gravity.
Things fall towards the ground. This is an unquestionable fact that is observed millions of times every single day. We (humans) have described this as “gravity,” and we have imagined many different explanations of what makes it happen. Since antiquity, there have been several explanations to account for the fact of gravity, all the way up to Newton and Einstein, and yet the proverbial apple does not care about the mechanism; it falls to the ground regardless.
Although we have a Theory of gravity, we do not think of gravity as something dependent on our personal opinions. Gravity happens, whether we like it or not. In this sense, gravity is both a fact and a Theory.
In our age of media sensationalism (or bite-size science), it’s not uncommon to hear someone proudly proclaim, “Newton got it wrong,” or “Darwin was wrong.” We’ve even heard, “Einstein got it wrong.” The truth is, these claims are spurious and shortsighted; it goes without saying that they are also wrong. We’ll deal with evolution in a moment; let’s finish with gravity first.
Take for example, Newton and Einstein. Newton didn’t get gravity wrong. If anything, given the limited access he had to observational evidence and experimentation, Newton’s insights into concepts like the inverse square relationship of the distance between two masses when calculating gravitational attraction is astonishing, and let’s not even talk about how, when the mathematics that he knew proved inadequate to explore this aspect of nature he invented calculus (more or less at the same time as Leibnitz).
Einstein didn’t overturn Newton, he improved on the accuracy of Newton’s laws. We still use Newton’s laws today even though Einstein’s theory of general relativity is more accurate. For example, pure Newtonian mechanics is perfectly adequate to model the basic motion of the planets around the Sun.
Picture credit: http://www.dimensionsinfo.com/shooting-target-dimensions/
If you look at this target from a distance of 200 yards, that large grey-black area encompassing rings 10, 9 & 8 will appear like a smudge, barely more than a dot in the distance. If you’re using a handgun or a rifle without a telescopic sight, at that distance you could proudly claim a bulls-eye if you struck the grey-black area, and yet up close it’s apparent there aren’t any shots that hit dead-center. In the same way, Newton’s laws fall broadly within the bulls-eye. Newton’s laws are extremely useful, but Einstein hit dead-center (at least to the best of our current knowledge. If the link between gravity and quantum mechanics is resolved, we may yet increase our accuracy even further).
When talking about theories, the same reasoning that we apply to gravity can be applied to evolution.
For some, evolution is a scary word, but it shouldn’t be.
The term evolution is a catch-all, a summation of more than a hundred and fifty years of scientific research and, unfortunately, religious controversy, compressed into nine letters. As a concept, evolution carries differing weight and different meaning in various people’s thinking, but it shouldn’t, as evolution has been clearly defined by science.
As with gravity, a vast collection of Theories of evolution have been used to explain this change of biological life over time through a variety of different mechanisms. The best available evidence points at natural selection as the most likely mechanism that accounts for evolutionary change.
As much as we like simple, straightforward answers, complex sciences like biology rarely resolve into a single solution. There can be numerous, interrelated causes contributing to the evolution of species. When DNA was first discovered, there were high-hopes that it would provide a single blueprint or instruction manual for life. Instead, what we find is that DNA is just part of the answer. The full answer encompasses epigenetics (the impact of the environment on our genes at the molecular level) and may even include an emerging field known as hologenetics (where the microbiome of symbiotic bacteria living within animals indirectly contributes to evolution in a kind of symbiosis). These are exciting fields of research, teaching us more about the mechanism by which life has adapted, diverged and thrived on Earth for billions of years.
Whether evolution has occurred by symbiosis, natural selection, a combination of the two, or even by an as yet undiscovered mechanism, our theories have no bearing on the fact of evolution. Life happened. Life has changed over time. The undeniable fact is that life on our planet has evolved over time. This has been thoroughly documented by many lines of evidence. This is a fact. Pure and simple. No “buts” or “maybes.”
Perhaps the most surprising thing about evolution is that it attracts any controversy at all, as it is quite simple and straightforward: the main imperative of life in the biological sense is to reproduce. To reproduce, you must be alive, therefore the kind of life that survives in a particular environment gets to leave offspring carrying its genetic legacy. Over time, we call this process adaptation.
The challenge species face is that there is fierce competition for limited resources, there’s disease, there’s predators, and so each animal species must produce offspring that survive to mate or they will go extinct. No child is identical to its parents, and so if gradual, generational changes provide an offspring with an advantage over its peers, then that change will be favored and slowly become a dominant characteristic. In this way, birds become lighter, lions become stronger, cheetahs become faster, etc. But there are physical limits. Become too light and a bird can’t migrate if it needs to. Become too strong and a lion needs more kills to drive its metabolism or risk starvation. Become too fast, and a cheetah may be more susceptible to strains or broken bones, etc. And so natural selection finds an equilibrium of maximum efficiency for a given species.
Picture credit: http://en.wikipedia.org/wiki/Nuclear_arms_race
Evolution is a Cold War within the animal kingdom, an arms race not unlike the one between the US and the USSR after World War II, with the stakes being extinction.
That life on Earth has changed over time is undeniable, and was a source of considerable interest in Victorian England when the fossils of terrible lizards (dinosaurs) were first uncovered.
And it’s not just that dinosaurs are extinct, 99.9% of all the species that have ever lived on Earth, including innumerable mammal species, are also extinct. The species we see around us today represent 0.1% of all the species that have ever existed. The species alive today are not merely survivors, they’ve inherited their pedigree from prior species. In some cases they’re really lucky survivors. We only have to go back to the dinosaurs, that proud lineage that thrived over millions of years, to see innumerable species wiped out in the proverbial blink of an eye by a random event in the form of a big rock that fell to Earth.
At its heart, science is about cataloging and categorizing natural phenomena in order to understand cause and effect. As more and more fossils were uncovered in the Victorian era, an interesting pattern emerged. Life could be ordered by strata, or layer. Fossils could be grouped together according to broad families of species, with each successive layer revealing a growing relationship down reaching through time.
Fossils are a time machine, a window into the distant past. They reveal how ancient species diverged and branched out into the species we see around us today.
Picture credit: http://en.wikipedia.org/wiki/File:Horseevolution.png (And by the way, this is only one example of the many lineages where transitional fossils have been documented).
Biologist J.B.S. Haldane was once asked what it would take to overturn the theory of evolution. His answer? Rabbits in the precambrian fossil layers.
As a humorous as this is, it’s an astute observation. In England, rabbits were a pest. Rabbits breed like, well, rabbits. Rabbits were everywhere, except in Precambrian history! And that struck Haldane as profound.
Picture credit: http://dogmapedia.wikia.com/wiki/Precambrian_rabbits
Dig down through layers of rock and stone and you’ll uncover fossils with similar skeletal structures to those species alive today, but there are distinct and clear differences. The deeper you dig, the more marked the difference. This sequential progression forms a pattern, revealing clues about how life has evolved on Earth. That life has evolved is a fact beyond controversy. How life has evolved is a theory that is well-tested and being refined further every day.
One common retort against evolution is to dismiss the concept by saying, “Oh, evolution is just a theory.” But such a flippant remark fails to understand that scientific theories are rigorously tested, subject to intense scrutiny, peer-reviewed, held to the highest standards of transparency and consistency, and brutally refined according to the available evidence.
A common fallacy prevalent in many circles is that scientific facts can be easily rendered invalid at a moment’s notice. This is not the case. Even if you are talking about the Theory of evolution, the sheer weight of evidence for the mechanism of evolution needs to be accounted for. There’s the fossil record, genetics, phylogenetics, laboratory experiments that have directly observed Natural Selection, and our own experience with artificial selection revealing the plasticity of species. All of these demand a clear explanation. The evidence we have, from a variety of different disciplines as far-flung as geology, all converge on the fact that evolution has occurred.
In the same way as Newton hit the bullseye while Einstein improved the accuracy, Darwin too hit the bullseye. Modern scientists like Stephen Jay Gould and Richard Dawkins have reported refinements to the theory of evolution and have contributed significant original ideas like punctuated equilibrium and the “selfish gene” idea.
In Darwin’s time, the main difficulty that stood in the way of a more complete acceptance of natural selection as a mechanism of evolutionary change was that nobody knew how traits were inherited. In the 20th century, the field of genetics has shown us how organisms transmit their genetic endowment and how that endowment changes over time (the concept of genetics reaches from Mendel to molecular sciences researched by Haldane, Mayr and Dobzhansky among others).
This brings up an interesting point about science, and one that we can only articulate by using the term evolution in a figurative, non-biological sense: Science is about evolution not revolution. We’ll explain what we mean.
Fields like string theory may very well lead to a revolution in our scientific understanding, but more than likely they too will be evolutionary, building upon rather than overturning existing notions. There are plenty of gaps to be filled in, but importantly there’s no evidence to be thrown out. Our understanding of biology, physics, chemistry, astronomy, etc., is always open to revision so as to be more accurate, but science really is about the evolution of ideas rather than a revolution. And nowhere is that more true than when it comes to evolution itself.
Picture credit: American Scientist
As sincere and well-meaning as creationists and proponents of intelligent design are, they do a disservice to science by cherry-picking concepts that suit their agenda, and this does no one any favors. Science takes no such shortcuts.
Good science is critical to our lives. The next time you open a can of soup, drive your car, or open a refrigerator, you are trusting good science. With the evolution of antibiotic-resistance strains of bacteria, the debate between science and pseudo-science is more than theoretical. In this regard, pseudo-rationality can get you killed.
Science has and always will be about removing agendas and looking at the evidence with an unbiased, critical mindset.
Evolution’s not a scary word. It’s an exciting concept, a wonderful glimpse into the mechanism by which life has thrived on Earth for billions of years.
For more information about evolution as fact and theory check out Stephen Jay Gould.
“Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.”