On evolution

Posted at 09:00 on 18 September 2017

Most of what I've said on this blog has been about the age of the earth and dating methods, and I haven't had much to say about evolution itself. This is partly because I'm not a biologist, but also because I've never been entirely sure exactly what position I should take on the matter.

I can fully understand why many Christians struggle with evolution. It's very much become a hot potato in the culture wars, with New Atheists and mockers pitting it against the Bible, and Christians taking the bait and becoming creationists in response. It does also pose some theological questions, such as what to make of Adam and Eve and the Fall. Some Christians (myself included) believe that the two can be reconciled; others believe that they can not, and that we must therefore reject evolution.

I'm not going to tell you that you have to accept evolution, or to what extent. That's for you to decide. But if you decide to reject it, whether in whole or in part, you still need to make sure your facts are straight about it. It's also important to be able to articulate exactly which aspects of the theory you are rejecting and why.

Make sure you are critiquing what the theory of evolution actually says.

You will only make yourself look clueless and ignorant, and quite possibly dishonest, if you attempt to debunk a cartoon caricature of evolution that no real scientist actually teaches. Portraying it as being about cats turning into dogs, or asking why there are still apes if humans evolved from apes, or likening it to dropping a bunch of Scrabble tiles on a table and coming up with Shakespeare, will all prove nothing more nor less than that you haven't a clue what you are talking about. The theory of evolution does not work like that.

Make sure that you understand what is actually meant by "evolution" in the first place. The formal scientific definition of evolution (taken here from Wikipedia) is very precise and refers to a specific process: change in the heritable characteristics of biological populations over successive generations. Make sure in particular that you understand the concept of common ancestry, because that is what you have to debunk — not shape-shifting, ridiculous hybridisation, or birds crawling out of dinosaur skins as if they were the Slitheen from Doctor Who. BioLogos has a couple of videos (here and here) explaining how evolution works and clearing up a lot of these misconceptions.

A lot of confusion comes about because young-earth creationists use the word “evolution” in a much broader sense than the scientific definition, conflating the process itself with its overall results (molecules to man), the timescale involved, dating methods, and a whole raft of philosophical or theological considerations that they perceive to be associated with it. More informally, they often use the words “evolution” and “evolutionist” as a passive-aggressive umbrella term for anything and everything in science that they don’t agree with. You may hear, for example, about “evolutionist” models of how the earth’s magnetic field works, even though how the earth’s magnetic field works has nothing whatsoever to do with biological evolution. Sometimes they even use the words “evolution” and “atheism” interchangeably.

To be fair, there is a tendency on the "evolution" side of the debate to de-emphasise the broad sweep of history in the definition of evolution (the frequently used definition of "change in allele frequencies over time" is an example of this), while evolution is also sometimes cited as justification for various atheistic or humanistic philosophies. But to react by turning it into a derogatory term for vast swathes of unrelated science and philosophy just causes confusion and muddies the waters. If you’re doing this, stop it. Just stop.

Then there is this expression "neo-Darwinism." I have no idea what that even means.

Be careful not to misrepresent the evidence.

Before you confidently say that "there is no evidence for evolution," or "there are no transitional fossils," please remember that your audience all has smartphones, and they can type "evidence for evolution" or "transitional fossils" into Google as you talk. Every hit that they get for these searches will be a hit to your credibility.

The fact remains that evolution is not "just a theory"; it is an evidence-based, scientific theory. You may wish to argue that the evidence has been misunderstood, and that other interpretations are possible, but to pretend that it doesn't even exist when quite clearly it does will just make you look like you're sticking your head in the sand.

Are there any good scientific arguments against evolution?

You're not going to falsify evolution, in the mainstream scientific sense of the word, in its entirety. The basic processes — descent with modification, mutations, natural selection, and even speciation — are readily observed both in the laboratory and in the wild. Furthermore, the fossil record shows indisputable evidence that these processes have been going on for billions of years, while genetic evidence such as endogenous retroviruses at the very least give humans and animals the appearance of being related. Either this is another example of "appearance of age," or else it represents real history. You decide.

The Intelligent Design community looks for limits on what evolution can explain. To this end, they have come up with a number of concepts such as irreducible complexity, which claims that certain structures such as the bacterial flagellum could not have come about through an evolutionary process. Not being a biologist, I can't critique irreducible complexity in much detail, but I get the impression that they're jumping the gun by declaring it to be a done deal. I would have thought that irreducible complexity would be extremely hard to prove, because it's not sufficient to show that one specific evolutionary pathway is impossible; you have to show that no alternative evolutionary pathways are possible either.

It's often claimed that evolution contradicts the Second Law of Thermodynamics, or that mutations can not produce new information. Unfortunately, these arguments are based on a fundamental misunderstanding of the concepts of entropy and information. Entropy is often illustrated in the popular press by comparing it to teenagers not tidying up their bedrooms, but this is a gross over-simplification that doesn't accurately reflect what entropy actually is, how it works, or what it does and does not apply to. Simplifications such as this can be useful in illustrating broad general principles to the layman, but you should never try to argue a point against them because the complexities and nuances of the subject that they gloss over will almost certainly render your argument wrong. Some properties of entropy and information are actually quite counter-intuitive: for example, it turns out that Shannon information and entropy are one and the same thing. Consequently, the Second Law of Thermodynamics means that mutations should produce new information.

There may be some other approach yet to be discovered, of course. I personally believe that at the very least, evolution must have required some "coaxing" to get us to where we are today, and I don't believe that it was an unguided, random process. But even if Intelligent Design does get proven, that won't necessarily falsify common ancestry, and it certainly won't take us back to six thousand years.

In the end of the day, what you make of evolution is up to you. But whatever conclusion you come to in the end, it is important to be honest about it. Like everything else, make sure that you know what you are talking about, and that your facts are straight.