Misconceptions about evolution I

This is part one of a two-part blog post aimed at addressing misconceptions about evolution. This part addresses claims that evolution doesn't exist. For the second part (addressing misunderstandings in how evolution works), click here.

Before I jump into a loaded topic, let me preface with a few notes. Firstly, this post is not an attack on religion/spirituality. The theory of evolution does not preclude belief in the supernatural because faith and science are separate and non-exclusive entities (e.g. deism). Science is a process of discovering new facts about the world and forming conclusions from them, while faith is a set of beliefs concerning what we can’t empirically measure. Just as this post is not an attack on religion, it is also not a defense of atheism.

Second, this post is not an attempt to lecture anyone. I don’t expect someone who doesn’t believe in evolution to read this and suddenly accept it. Rather, this post is meant to clarify misconceptions on evolution that are often cited in arguments against it. I would hope that any reader of this blog who encounters someone who doesn’t believe in evolution would use this post’s contents as a means to inform, not insult. Open-minded discussion, I think, is the key to any sort of reconciliation between people who don’t see eye to eye. 

While this post will explain what evolution isn’t, let me briefly explain what evolution is. Evolution is a change in allele frequencies in a population from one generation to the next. Alleles are gene variants; for example, the genes for eye color will have alleles for blue eyes, brown eyes, etc. Evolution means that the gene pool of Generation 2 isn’t identical to Generation 1. These changes can come from:

• natural selection (e.g. due to a drought, an island’s plants only produce small seeds and large-billed finches die because they have nothing to eat. Because they didn’t reproduce, the alleles for large bill size are not passed on. Next year, the average finch bill size is smaller),
• mutation (e.g. an error in DNA replication leads to a slightly-different protein being produced every time the cell divides),
• genetic drift (e.g. rats hidden on a cargo ship come onto an island with no rats. While the parent population on the mainland may have had a wide range of coat colors, only the migrant rats’ coat color alleles will get passed on. If no one has a white allele, no baby is going to be white), and 
• gene flow (e.g. male elephants from outside the herd immigrate and mate with the females).

Most of the time, an error in DNA replication (mutation) does nothing because it’s in an area of the DNA that never gets coded anyway (i.e. “junk DNA”). When the error is in an area that is coded, the organism often dies (or rather, is never born) because the new protein produced from that DNA usually doesn’t do what the organism needs for survival. Rarely, the mutation actually makes the protein better, or a big segment of DNA is accidentally copied so now there are two identical proteins being produced, so any mutations one copy gets can accumulate because there’s still another functioning copy (i.e. paralogs). On enormous time scales, these mutations can accumulate and completely change how an organism looks internally and externally. However, for every successful species we see today, there are billions of species that didn’t make it. This means that they hit an evolutionary dead-end; the mutations that got passed on and accumulated either led to a body plan or behavior that just couldn’t compete with a different species, or the environment changed (e.g. an asteroid strike) and the morphology that worked before just didn’t work any longer.

So, let’s get started on the misconceptions!

1. “Evolution is a ‘theory,’ which means it hasn’t been accepted by scientists.”
While theory in the colloquial sense refers to something we’re not sure about, a scientific theory refers to an explanation of a natural phenomenon that is strongly supported by experimental evidence. See the theory of gravity or the theory of electromagnetism.

2. “Scientists often disagree with one another, which indicates we shouldn’t trust evolution.”
Science works because it can be tested, and that testing can come from incredibly varied viewpoints. A hypothesis cannot be accepted unless it can be refuted, so scientific discoveries are always very carefully worded; you never ‘prove’ anything in science, you only disprove all known alternatives at the time. But the beauty of science is that ideas can be refuted. If the sun rose from the west tomorrow, we’d have some serious rethinking to do regarding our accepted explanation for how the Earth rotates. Or if an Italian guy pointed a telescope at Jupiter and discovered moons orbiting it, we’d have to reconsider our belief that everything in the Solar System orbits the Earth… or did that already happen??

In all seriousness, while researchers may argue over the details of evolution (e.g. whether sympatric speciation is possible), evolution itself has been long ago accepted as the best explanation for life’s diversity. As the community gains more information, it may refine evolutionary theory, but this does not mean that the theory is flawed.

3. “The complexity of today’s species could not have happened by chance.”
Biologists agree! That’s because the complexity didn’t happen by chance. Today’s species are an accumulation of changes that happened over billions of years. An analogy that opponents of evolution use is that you have a slot machine with 50 slots. Each slot has a letter, and there are 27 options for each slot (all the letters of the alphabet, and a space). You pull the machine’s lever, and all the slots start spinning. You would have to pull the lever 3.7 x 10^71 times before you’d get the sentence “I am a dancing banana man and I love peanut butter.” But evolution doesn’t operate like that; it’s an incremental process. Say, instead, the fourth time you pulled the lever, you got an ‘I’ in the first slot and you got to keep it. A few pulls later, you get the space in the second slot and get to keep it. In this way, you’d eventually build that full glorious sentence.

A real-life example to consider is bacterial resistance to antibiotics. If you took Antibiotics A, B, C, D, and E and ran them all through a bacterial culture, it’d be extremely unlikely that any cell would survive that onslaught. If you expose the bacteria to a small dose of Antibiotic A, though, a lot of cells would die but a few would likely survive due to having a mutation that protects them against that antibiotic. Those cells, suddenly facing no competition from other bacteria, would multiply like crazy. Repeat this process one by one with the other antibiotics… and at the end, you’ll probably have superbugs resistant to all five antibiotics.

4. “If evolution is real, why are there still chimpanzees around?”
Humans did not evolve from chimpanzees; humans and chimpanzees diverged from a common ancestor 5-8 million years ago. With the exception of species that humans have artificially selected for (e.g. dogs coming from wolves), no species today coexists with its ancestor.

5. “Evolution violates the second law of thermodynamics.”
Another way of saying this would be that the entropy of a closed system cannot decrease, and that if the Earth is a closed system, increasing complexity (e.g. a human has a more developed respiratory and circulatory system than a fish) thanks to evolution can’t occur. However, the Earth is not a closed system because it receives energy from the sun. Also, the second law of thermodynamics refers to energy in a system, which is unrelated to morphological complexity.

This list is not exhaustive. I found ideas for which misconceptions to address from the following sources: 

• Wikipedia: "List of common misconceptions - evolution"
• UC Berkeley's "Understanding evolution"
• Talk Origins: "Five Major Misconceptions about Evolution"

This is part one of a two-part blog post. To read about misconceptions on the details of how evolution works, click here.