Biology 101: Evolution

In reply to my last post, I had this question:

“I don’t have any problem with christianity and evolution from the POV of what the first three chapters of genesis say, but…. doesn’t evolution necessitate that God actively chose to create us through a competitive process whereby the strong live and conquer, and the weak die and are destroyed – isn’t that fundamentally contrary to Christian ethics and the God we meet in the Bible? Why would God choose to create in that way?” – TheologyJohn

That’s quite a poser! But before I can start to answer that, let’s have a look at evolution. It’s an interesting process, because it works on lots of levels – from the whole organism right down to the DNA itself. Evolution itself is more about the overall process of change in characteristics inherited from the parent(s), and is driven by various things (pressures that kind of define what is successful in the environment the living thing is in) to go in a certain direction. So water puts pressure on living things to either a) be happy with just floating around (if you’re veery tiny, like bacteria), b) swim around to get air/food/anywhere, or c) “breathe” under water.

But biology is beautifully complicated and detailed, and the important things in this are the smallest of all – DNA and genes.

DNA is a molecule that all living things have (and viruses too – but the scientists aren’t quite sure as to whether they are alive or just… undead), and is made up of two strands that hold together and twist around like this:

The backbone of each strand is made up of sugar and phosphate molecules (if you want more detail, you’ll have to look it up) and sticking out from the backbone are DNA bases. They pair up by things called hydrogen bonds, which work a bit like molecular magnets.

There are four bases that our DNA has: Adenine (A), thymine (T), guanine (G) and cytosine (C). As the pretty picture shows, adenine and thymine stick together, and cytosine and guanine stick together. The A will only stick to a T, and vice versa, and the same goes for C and G because of the number of hydrogen bonds that they can make (A&T make two, C&G make three).

Genes are regions of double-stranded (i.e. like the picture) DNA that encode proteins. Proteins are made up of lots of units called amino acids, and each amino acid is coded by three DNA bases. So the amino acid methionine is coded for by an A-T-G sequence. Basically, enzymes unzip the DNA so that one strand is exposed, and copy the DNA into a form that can be recognised by the enzyme that reads the copy and sticks amino acids together to make proteins.

It’s a pretty cool system. You know how much computers can do? They just run on binary code – two “letters”, 0 and 1. But living things run on a code with four letters, and this means that you can get things that swim, fly, glow in the dark, and make tea (a very important skill, I feel)! There’s so many combinations of the four bases that there are more triplet codes than amino acids, so each amino acid is coded for by three or four codes. Add to this the number of amino acids that our cells can use, and you have big numbers of biological potential!

Back to evolution. As I’ve mentioned, evolution works through change. Our DNA doesn’t stay the same all the time – there’s lots of stuff around that can damage it, and our own cells can make mistakes when copying and repairing it. So soon enough the base sequence of the DNA will change. Thankfully, we’ve got some awesome proteins in our cells that can fix almost all dodgy DNA. But every so often, a change doesn’t get fixed before it’s copied to make new DNA, and is part of the new DNA forever. This is a mutation. Sadly, mutations don’t mean that we can get new super-human powers or turn into human lizards or whatever. Sorry, superhero fans. But they can affect the proteins that are made from them. Having a different amino acid in a protein can change its shape, or whether or not it can do the job it’s meant to do, or not affect anything – remember I said that every amino acid has a few codes? It’s a good failsafe against problematic mutations.

So these mutations change proteins, which can change what the proteins do. They could change how a protein looks, giving a different colour of hair; or how it functions, giving some form of intolerance. Basically, proteins do pretty much everything.

The important thing in survival genetics is passing on your DNA to the next generation. Don’t ask me why, it’s just the way it is. DNA can’t think, it doesn’t want anything, but for some reason the main purpose of living things is to pass their genetic information on (or so I’m told). So living things reproduce a lot!

Back to the big picture. In an environment (let’s say my back garden) there are lots of things going on. The air will be a certain temperature, it will be sunny in different places, and there could well be things that eat you (especially the neighbour’s cat). You’ll have to search for food. You’ll have to sleep somewhere. All of these things put pressure on things living in the environment – called selection pressure because they select for different characteristics. Being under the apple tree selects for things that can live in the shade. Being slimy and hungry for the home-grown peas selects for things that can hide from my slug-killing mum. And so on. In the case of the slugs, the pressures on them will select for mutations that mean that somehow they can survive the slug holocaust that happens after a rainy spell.

That’s only half of the story, though. Natural selection – pressure from the environment and competition to survive with other living things – only accounts for the survival part of the story. Reproduction is also really important. With living things that don’t have sex, reproduction is pretty easy. Most of the time, it’s just growing and dividing like bacteria, so new characteristics that come from mutations are passed down the generations fairly simply. Characteristics that don’t work get killed off with the bacteria that fail at life because of them. But for living things that do have sex, it gets more complicated. After all, someone else has to want to reproduce with you. So besides the fairly logical “survival of the fittest” there’s the “survival of the hottest”.  This means that you can get some random things developing, like long tails, or bright feathers, or weird courting rituals, just because the opposite sex like it. The theory goes that these things must show something about the individual that is good for survival, like “I’m so awesome that I can put energy into PRETTY COLOURS!!!” Of course you’d want the Awesome Gene for your offspring because it makes them better at surviving, which means your genes will live on. Granted, you do have to share gene-space with your mate’s genes in your offspring, but combining can be a good thing. It can get rid of dodgy genes, and create more diversity.

So there’s natural and sexual selection, which are both part of evolution. It is a bit brutal, because it’s all about death and dog-eat-dog survival.

Why would God choose to create like this?

To be honest, I don’t know for sure. Death is a fundamental part of evolution, and if God created by evolution, we have an inconsistency with the Genesis account where death didn’t happen until after Adam and Eve (the first humans, according to the Bible) made a big booboo by eating that fruit. So we’ve got a problem there. Personally, I’m ok for this to be a grey area. I know that God created the world and that the Bible is true. I also know that evolution is a pretty sound theory – it underpins pretty much all of our understanding of living things, and it works. The details between the theology and science are tricky, because we simply weren’t there so we can’t know for sure, but what could (I stress could; I’m no expert) have happened is that death was there, but it’s spiritual death that Adam and Eve introduced.

However, to create a process that not only makes new versions of things, but continually does so, while adapting to all changes and pressures around, is pretty clever. I think it’s incredibly creative.

There’s a paper by R.J. Berry and published free online by the Faraday Institute that talks about evolution, and it’s well worth a look: (http://www.st-edmunds.cam.ac.uk/faraday/resources/faraday%20papers/Faraday%20Paper%2012%20Berry_EN.pdf). Seriously, go and read it, it’s only four pages long. On p.3 it mentions that even Darwin had a problem with the brutal nature of evolution. Unfortunately, there’s not much to reconcile the ideas of brutal evolution and a loving, compassionate God in the paper. BUT it does say that there is a value to pain and suffering – pain is a good protective mechanism, and tells us when something is wrong, and suffering helps to mature us (Proverbs 23:13; Romans 5:3; Hebrews 5:8). Also, it is through Jesus’ suffering and death that we have a way of escaping suffering in hell, and what Jesus did on the cross affects the natural world as well as our human world – we have hope of everything being renewed in heaven.

It pains me not to give a conclusive answer, but I hope that’s helped!


I relied heavily on my first year genetics notes for this, so thanks to the lecturers! And credit to the Faraday Institute for the insights from their paper as well. Go and look them up, they’ve published some fascinating papers on science and religion (Christianity in particular) that are very faithful to both the science and religious thought.

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4 comments
  1. Thanks very much Kathryn – was fasinated by this post, has definitely given me food for thought 🙂 – and sorry for giving you such a hard question to answer!

    P.S. You are *such* a geek. 😛

  2. No worries. It’s good for me to go back and look at the old lecture notes! And I could have said a whole lot more about DNA and genetics – I had several modules on it.

  3. Jeremy Blakey said:

    Hi Kathryn. Just seen this good post. Just to add that the fall ushered in human death; it cannot be demonstrated from scripture directly that there was no animal death before the fall.

    • Hubbardy said:

      Thanks, Jeremy. And that’s a very good point!

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