An Evolution Primer for Creationists Skeptoid #10 November 30, 2006 Podcast transcript | Listen | Subscribe

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Some creationists may be concerned that some of their standard arguments against evolution sound dismissive or patronizing. This is probably true: in any debate, it's common to frame your opponent's arguments in a weak light. Sometimes this is done deliberately to make evolution sound ridiculous, and sometimes it's done accidentally through ignorance of what evolution is and how it works. Since misinformation and ignorance are poor platforms on which to build any conversation, I present the following Evolution 101 Primer for the benefit of creationists who want a correct basic understanding of their foe. I think the best way to do this is to dispel the three most common evolution myths.

Myth #1: Men evolved from apes.

This is the oldest and wrongest misconception about evolution. Nobody has ever suggested that one species changes into another species. Some criticisms of evolution show illustrations that fraudulently purport to show what evolutionists claim: that a salmon changed into a turtle, which changed into an alligator, which changed into a hippo, which changed into a lion, and then into a monkey, and then into a human being. Of course such a theory would seem ludicrous. But it's pure fantasy and has nothing in common with real evolution.

The diversification of species is like a forest of trees, sprouting from the proverbial primordial soup. Many trees die out. Some don't grow very tall. Some have grown a lot over the eons and are still growing today. Trees branch out, and branches branch out themselves, but branches never come back together or combine from two different trees. The path of a species' evolution is shaped like the branch of a tree, not a donut, not a figure 8, not a ladder. To embrace evolution, you need not — must not — think that a salmon turns into a zebra, or that an ape turns into a man. It's simply not genetically possible.

We've all seen the other famous illustration, where a monkey morphs into an ape, that morphs into a caveman, that morphs into homo sapiens. If you climb back down the tree branch, you will indeed find earlier versions of man where he was smaller, hairier, and dumber, but it won't be a modern ape. To find a modern ape, you'd need to go even further down the tree, millions and millions of years, find an entirely different branch, and then follow that branch through different genetic variants, past numerous other dead-end branches, past other branches leading to other modern species, and then you'll find the modern ape. Never the twain shall meet.

Myth #2: Evolution is like a tornado in a junkyard forming a perfect 747.

This is a popular manifestation of the argument that evolution depends on randomness, and so it would be impossible for complex structures to evolve. Well, this is half right, but completely wrong in its totality. Random mutations are one driver of evolution, but this argument completely omits evolution's key component: natural selection.

Obviously, in reality, if a tornado went through a junkyard, you'd end up with worse junk, not a perfect 747. No evolutionary biologist, or any sane person, has ever claimed that you would. It's ridiculous. The tornado is meant to represent the random element of evolution, but genes don't mutate catastrophically all at once, like a tornado. Here is a more accurate way to use this same analogy.

Imagine millions of junkyards, representing any given population. Now imagine a group of welders, who walk carefully through each junkyard, twisting this, bending that, attaching two pieces of junk here, cutting something apart there. They do it randomly and make only a limited number of small changes. Sometimes they don't change anything. This is a far more accurate representation of how genes mutate within an organism. It's not a single cataclysmic tornado.

Now comes the natural selection. Let's test every piece of junk in every junkyard. Does anything work better? Does anything work worse? With millions of changes in millions of junkyards, it's inevitable that there will be some improvements somewhere. Part of natural selection is the eventual removal from the population of any organisms that are less well adapted, so to simulate this, we're going to eliminate all the junkyards where the junk was worse after the welders made their mutations. This leaves only junkyards that are stable, or that are improved. To simulate the next generation of the species, we replicate all of our current improved gene pool of junkyards, and again send in the welders. They make a few random changes in each, or no changes at all.

Each time this entire process happens, the population of junkyards improves. But this doesn't happen just a few times. It happens millions or billions of times. The changes made by the welders are countless. The vast majority of changes are either useless or make things even junkier. Since natural selection automatically filters out the poorly adapted junkyards and rewards those rare improved junkyards with additional procreation, our population of junkyards gets better and better. Things start to take shape in the junkyards. Useful things. Stronger things. Things with abilities that nobody could have predicted. Any given piece of junk that improves is replicated in many junkyards, and reappears in millions of slightly altered forms each time. Pick the best version from each generation, and you can literally watch the same piece of junk evolve into a better, stronger, more useful, and better adapted machine with more capabilities. This is evolution.

Myth #3: Evolution is just a theory.

First of all, if you believe that most biologists consider evolution to be "just a theory", you're behind the times. Almost all biologists call it a fact, and not because they feel any particular need to respond to creationists.

Second, when creationists try to put evolution down by dismissing it as "just a theory", they're actually acknowledging its scientific validity. To understand why, it's necessary to understand exactly what a theory is. When creationists use the term to disparage evolution, they really should be using the word hypothesis. A hypothesis is a provisional idea, a suggested explanation that requires validation. Evolution is well beyond that stage, though; even the staunchest anti-evolution creationists assign evolution the much higher status of theory.

In order to qualify as a theory, evolution had to meet the following criteria:

• A theory must originate from, and be well supported by, experimental evidence. It must be supported by many strands of evidence, and not just a single foundation.
• A theory must be specific enough to be falsifiable by testing. If it cannot be tested or refuted, it can't qualify as a theory.
• A theory must make specific, testable predictions about things not yet observed.
• A theory must allow for changes based on the discovery of new evidence. It must be dynamic, tentative, and correctable.

Notice that last one: tentative, correctable, and allowing for future changes. Creationists often point out that the theory of evolution is incomplete, like any theory, as if this disproves it. To be a theory, evolution must be incomplete by definition, and (no pun intended), constantly evolving.

The strict scientific definition of a fact is both simpler and hazier. A fact is a verifiable observation, and evolution is verified so many times throughout the entire science of biology that most biologists call it a fact. However many scientists contend that every fact has some element of theory to it, so in this sense, it doesn't really make any difference whether evolution is called a fact or a theory. Since biologists are always learning more and adding to our knowledge of evolution, it's probably best to leave it as a theory.

I hope some creationists find value in these explanations. As always, your comments are welcome on the web site.

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