I was hitchhiking in New Zealand a couple of years ago when I got into a conversation about evolution with my driver. I don’t remember the details of what was said, except that she told me, “I didn’t give birth to a baby monkey. I didn’t grow a monkey inside of me.”
Misconceptions about evolution are common. For me, many of them dissipated when I learned the definition of a scientific theory and why evolution is the cornerstone of modern biology. What an enormous and fascinating topic! I will go over only a few misconceptions (to avoid writing a novel) and briefly describe common descent, why evolution is not “just” a theory, how it exemplifies the very opposite of randomness in light of natural selection and that it is a simple yet elegant explanation for how organisms are affected by and interact with the natural world.
“My grandpa wasn’t a monkey!”
First let’s tackle the monkey misconception. We didn’t evolve from monkeys. Evidence shows that humans share a common ancestor with apes, namely gorillas and chimpanzees, but we didn’t evolve from them either. Common descent describes the relationship between us and our predecessors when a new species arises from an ancestral population.
You may remember that apes are most distinguishable by their lack of a tail. Lesser apes include gibbons and resemble monkeys more than great apes. Great apes are a family called Hominidae including chimps, orangoutangs, gorillas and humans, all of which are different species. Evidence also shows that all the observable life on earth, from worms to whales to viruses, arose from a common ancestral organism.
“Evolution is ‘just’ a theory.”
“Theory,” by the everyday definition, implies a speculation or a guess. However, it is VERY IMPORTANT to understand that in science, a “theory” means much, much more than a hunch. An educated guess perhaps? No. A hypothesis could be an educated guess, but a hypothesis is not the same as a theory. A theory is a confirmed hypothesis that is backed by evidence. A proven theory is a fact.
“Evolution is not a fact.”
The theory of evolution is a fact (a true statement about the world) in the same way that the theory of gravity (the relationship of force between bodies of mass) is a fact and germ theory (the attribution of infectious disease to microorganisms) is a fact. Most who deny evolution would not deny gravity or germs, but these explanations have been developed by the same methods as the theory of evolution. Calling it a theory is the highest possible achievement of science. A law in science is not “higher” than a theory and neither is a fact.
Evolution is the basis of modern biology and the best explanation we currently have for the staggering variety of life we see today and find evidence for in the fossil record. It is not a conspiracy cooked up by evil biologists for some malicious purpose.
“So you are saying the diversity of life happened by chance?”
EVOLUTION BY NATURAL SELECTION SUGGESTS THE OPPOSITE OF CHANCE. While mutations in DNA occur at random throughout the reproduction process, natural selection is the process that pinpoints and propagates mutated traits that end up being useful for survival. It’s simple: because the likelihood of the organism possessing advantageous traits to reproduce is greater, there is a greater chance of those traits being inherited by offspring. Evolution by natural selection results in organisms “sculpted” by natural selection to survive within their unique environments and in relationship to other organisms in the food chain.
Charles Darwin (1809-1882) and Alfred Russell Wallace (1823-1913) developed the idea of natural selection making the theory of evolution, which dates back to the Greeks, more viable and understandable. Again, natural selection is the idea that connects the complexity of life on earth with random mutations that occur during DNA replication. It is the driving force behind evolution that makes it the very OPPOSITE OF RANDOM, resulting in specific traits surviving over others and the ability for life to exist in an enormous range of locations, including thermal vents under the ocean, African savannas, isolated islands and rain forests.
“Irreducible complexity shows that evolution is impossible.”
The argument that some aspects of life, like the human eye, are “irreducibly complex” is outdated and long-refuted. Using the example of the eye, the argument goes that every part of the eye as a whole has to be present at once in order to function, so how could it have evolved? After all, there is no such thing as “half an eye.”
First of all, there is no one version of the eye, even among humans. There is variation; some are far-sighted, some are near-sighted, and some are blind. No eye is “perfect,” whatever that means. This suggests a process behind the eye’s development and scientists have found several primitive examples.
Some animals have, or had, only light sensors for “eyes.” Some fish have no eyes at all because their environment is total darkness. Some eyes are better at heat detection than light detection. Birds vision is much sharper than humans. Cats see at night as well as we do during the day because of a reflective sheen over their eyes (which is why they seem to glow). This variation shows that eyes come in many shapes and sizes, exist in “parts,” and have varying functions. Even a primitive eye would, according to natural selection, help an organism survive longer than it’s counterparts, giving it a reproductive advantage.
We have this idea of successive species becoming “better.” In evolution, this means “fitness to environment” and is based on frequency of reproduction of particular traits. It makes no sense to use good or bad in this case. It is logical that with time, human eyes can become better suited to the environment than they are now, which would mean it can become more complex than it is now.
To close, the theory of evolution is simple and elegant. This means that the mechanism is simple (mutations in DNA that are advantageous become more frequent in a population) and the result is elegant (complex, beautiful organisms of staggering variation). Am I saying that in this case simplicity gives rise to complexity? YES. I am aware that the Second Law of Thermodynamics states that in a closed system this should not occur. Guess what? Life in earth’s terrarium is not a closed system: we have the sun upon which most life depends.
For an example of how simplicity gives rise to complexity, check out the Mandelbrot Set. In fractals, a simple mathematical formula gives rise to a strikingly complex image. How cool is that?!
Also, you may want to do some reading:
Charles Darwin: The Origin of Species
Jerry Coyne: Why Evolution is True
Neil Shubin: Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body
Richard Dawkins: The God Delusion
Love the way you address each of the arguments, So clear.
ReplyDeleteI'm pleased that you think so. There are so many more arguments that I did not address here, but they are bound to come up in other posts. Thanks for reading :)
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