We humans tend to perceive ourselves as being in a league above other organisms with respects to our intelligence and wit. Yet a significant part of the human population lives in a reality that’s largely disconnected from science, including the science of evolution.
Within scientific circles, it’s widely accepted that all organisms, ranging from humans to pandas to E. coli bacteria, are a product of evolution. Only a very tiny percentage of scientists take issue with the notion that we’re built the way we are because evolution made us that way. Outside of such circles, however, opinions are more mixed, particularly in corners of the world where religion holds a dominant position. In such areas, one will invariably come across people who of the belief that one or more almighty Gods created all of life in its present form and that the Earth is just a few thousand years old.
Such notions conflict with scientifically established facts regarding the origin and development of life.
It’s important to point out that evolution isn’t some obscure, inexplicable thing, which is the impression that one may get from hearing how it’s described by people who are opposed to its existence. Rather, it simply refers to a process of change. Typically, the term is used to describe the changes that have occurred in the ecosystem of the Earth over eons of time. There is no goal or ultimate purpose to evolution, and there’s nothing transcendental about how it happens. It’s a natural process that can be clearly defined and demonstrated.
Furthermore, it’s important to recognize that the terms evolution and natural selection don’t mean the same thing. Natural selection is a mechanism/way by which evolutionary change occurs. It’s not the only mechanism, but it’s a very important one. It’s also the theory or principle that forms the foundation of Darwinian medicine and is at the center of discussions about speciation and the origin of man; hence, it’ll be the primary focus of this article.
The scientific underpinnings of evolutionary theory
People who are opposed to Darwinian notions regarding the workings of nature commonly cling to the belief that the scientific foundation upon which the theory of evolution rests is weak, small, and fragile, often dismissing evolution as “just a theory”. By doing so, they fail to acknowledge that the word theory is used differently in scientific and non-scientific arenas, as described below.
A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested, in accordance with the scientific method, using a predefined protocol of observation and experiment. Established scientific theories have withstood rigorous scrutiny and embody scientific knowledge.
The definition of a scientific theory (often contracted to “theory” for the sake of brevity) as used in the disciplines of science is significantly different from the common vernacular usage of the word “theory”. In everyday speech, “theory” can imply that something is an unsubstantiated and speculative guess, the opposite of its meaning in science. (1)
The theory of evolution via natural selection is an established scientific theory, it’s not an untested or rejected theory, and it’s certainly not a wild idea or guess. The scientific foundation upon which it rests is extremely solid, large, and dense. The evidence for evolution is beyond overwhelming! (2, 3, 4, 5, 6, 7)
Evolutionary science is a ubiquitous part of the world of science. It’s a natural component of scientific papers that deal with topics that have to do with the living world, including papers that cover nutrition and medical-related matters (A few examples: 8, 9, 10, 11, 12, 13). Scientists don’t question whether populations evolve or not, they just operate under the belief that they do. Not because they are reckless, but because they know that the science on evolution is air-tight. It’s an established fact that evolution occurs.
The idea that life changes over time as a result of evolutionary processes is supported by several lines of scientific evidence (2, 3, 4, 5, 6, 7). These days, we no longer have to rely merely on the insights that can be gained from looking at fossils, examining plants and animals in a rudimentary manner, or observing nature, which is largely what Darwin and his contemporaries did. We have the option of utilizing a whole array of advanced tools, instruments, and research methods in our pursuits of truths.
The key thing to recognize is that the investigations that have been carried out via the use of these novel tools and procedures haven’t cast doubt on Darwin’s initial supposition regarding the fundamental nature of evolution. On the contrary, they have strengthened the Darwinian position. They’ve brought about new discoveries, refined certain key concept, and improved our understanding of how evolution occurs; however, they haven’t altered the fundamentals of the evolutionary theory.
The basic concepts and ideas that Darwin laid out in his seminal publications have very much stood the test of time. This is clearly highlighted by modern genetics research, which among other things has revealed, not surprisingly, that organisms neatly fall into line on the tree of life/evolution when their genomes are examined, as explained in the video below.
Evolution is happening all around us
One of the main reasons why some people question the idea that life is constantly evolving is undoubtedly that morphological evolution tends to be a slow process. Our bodies obviously don’t change over night. Neither do the physiological structures of other animals. It typically takes many generations for major changes in the gene pool of a population of multicellular organisms to occur.
What’s important to point out though is that evolution can be rapid. Bacteria, for example, evolve at a much more rapid pace than large organisms such as us. This is clearly seen in the case of antibiotic resistance. If you expose a group of bacteria to an antibiotic compound, any bacteria that either carry or come into possession of genetic variants via mutation or horizontal gene transfer that make them resistant to the antibiotic in question will be at an advantage in the struggle for existence. Bacteria that are susceptible to the antibiotic on the other hand will be at a disadvantage.
This is a classic example of natural selection. Basically, the infusion of the antibiotic compound into the population of bacteria initiates a selection event. We don’t have to look far and wide to find real-life examples of this type of evolutionary process. All we have to do is have a look back and see how the gradual incorporation of new antibiotics into clinical medial practice has shaped the evolution of bacteria, in particular the evolution of so-called superbugs.
As we move into the animal kingdom, the rate at which evolutionary change occurs slows down, in large part because generation times are markedly longer. Unlike bacteria, we’re not able to make copies of ourselves “in the blink of an eye”. With that being said, evolution can occur fairly rapidly even in humans, given that the selection pressure is strong. The evolution of lactase persistence is an excellent example of that. In just a few thousand years (a short time period in evolutionary respects), the trait that confers an ability to break down the milk sugar lactose post-infancy went from being extremely rare to becoming extremely common in certain parts of the world.
Such situations of “rapid” evolution have obviously also been documented in other species, as shown in the figure below, which describes one of the most prominent and conspicuous cases of evolution via natural selection that has ever been documented:
More cases of rapid animal evolution are described here:
4 questions for the skeptics
It’s somewhat surprising that some people question the notion that the ecosystem of the Earth has evolved – and continues evolve – via natural selection, given that one can quickly deduce that natural selection is “in effect” simply from studying the workings of nature.
The next time you come across someone who doubts the merits of the theory of evolution via natural selection, you may want to ask him or her the following four questions:
- Do you agree that there is variation in nature? I.e., some American black bears are bigger and stronger than other bears.
- Do you agree that organisms pass on genes to their offspring and that some variable characteristics/traits are (at least partially) heritable? I.e., the children of tall people tend to become taller than the children of short people.
- Do you agree that not all organisms are equally successful at surviving and reproducing? I.e., some pandas get more offspring than others.
- Do you agree that an organism’s ability to attract a mate, survive, and reproduce is affected by the organism’s height, strength, skin color, and/or other variable traits that have a heritable basis? I.e., a leopard’s ability to get a hold of food and ultimately bring children into life is partly determined by how fast it’s able to run, which in turn is partly determined by the genes it inherited from its parents.
If his or her answer to all of these questions is yes, then he/she is actually on board with the fact that living things evolve via natural selection. In other words, he/she recognizes that Darwin’s primary assertion is correct.
The most logical explanation, by far, for why living organisms look, function, and behave the way they do is that they were “designed” by natural selection. When evolutionary science is brought into the equation, the different pieces that make up life as we know it naturally come together and fall into order. With that being said, it’s important to point out that supernatural and evolutionary beliefs aren’t necessarily mutually exclusive. Many of the beliefs and tenets that are integral to religions such as Christianity, Islam, and Buddhism do indeed conflict with Darwin’s teachings; however, it’s certainly possible to believe in supernatural phenomena, gods, or divine forces while at the same time acknowledge that organisms descend from a common ancestor and were crafted by evolution.