DNA, evolution and challenges for all

December 24th, 2015 in clues. Tags: , , , , , ,

Food for Thought

DNA

It is easy for human beings to become set in our thinking, quite satisfied that we know the truth about some matter, and therefore quite unwilling to change, or even consider other ideas. We can become quite “tribal” about our viewpoints, and defend even small differences quite vigorously. It can be as minor as Apple vs Microsoft or our football team vs theirs, but it can also be something more important like left vs right in politics or atheist vs theist.

Sometimes some new information comes along to challenge our viewpoint more strongly, and give a thoughtful person food for thought. Our understanding of DNA is an example of this. (I intend to look at a few examples of food for thought over the next few posts.)

What DNA is and how it works (very briefly!)

I have been researching family history for several years now, and have recently had my DNA tested to identify possible genetic matches – people who are related to me, perhaps as distant as 5th cousins – to try to make some breakthroughs in a difficult search. I’ve never studied biology, but I’m learning some interesting facts.

DNA

DNA is a complex organic molecule shaped somewhat like a spiralling ladder which stores enormous amounts of information (almost 3 billion “base pairs”). DNA controls how our body grows, by providing code to make the different protein molecules which make up different parts of the body. There is DNA in every cell in our bodies, apart from red blood cells, and “cornified” (i.e. “dead”) hair, nails and skin cells.

Our 23 chromosomes are long strands of DNA, each comprising many genes. The 23rd chromosome determines gender. The mother will always pass on an X chromosome, but the father may pass on either and or a Y – XX makes a female and XY makes a male. Cells also contain mitochondrial DNA, which is found in a different part of the cell. It is passed on by the mother to all children, but males do not pass their mitochondrial DNA to their children.

When a child is conceived, they receive half their DNA from each parent, a process with enough randomness to ensure that siblings don’t have the same DNA unless they are identical twins.

Mutations and random variations occur to varying degrees in the different parts of DNA.

DNA genealogy

Almost all of human DNA is exactly the same, but a small amount varies. Each of us inherits long segments of DNA from each parent, shorter segments from each grandparent, etc. So the length of segments two people have in common is an indication of possible relationship – long identical segments indicate the two people share a common ancestor only a few generations back, but short identical segments indicate any common ancestor is likely many centuries or even millennia back.

Autosomal (chromosomes 1-22), X, Y and mitochondrial DNA testing can also indicate in which part of the world a person’s ancestors lived, by comparing that person’s DNA with characteristic DNA from different areas.

DNA testing can, of course, be used it identify disputed paternity, and allow adoptees to identify biological parents.

Human ancestry

The same principles can be used to identify ancient ancestry, and thus identify lines of human evolution and migration. For example, extraction of DNA from ancient skeletons has shown that:

  • All humans appear to be descended from a single female (sometimes called mitochondrial Eve) who lived something like 100,000 to 200,000 years ago, probably in Africa. She was probably not the only woman alive at the time (we have more genetic diversity than that), but the only one who has descendants living today.
  • Likewise, all humans are descended from a single male, who may have lived somewhere in the same period, also in Africa (although estimates for this date seem to change with every new study).
  • It is considered unlikely that these two common ancestors lived at the same time and place – although who knows? The best estimate for the dates for these two ancestors now overlap, which wasn’t the case until recently.
  • It appears that there was a small amount of interbreeding between humans (homo sapiens) and Neanderthals, perhaps about 50,000 years ago in Asia Minor, so most humans alive today probably have some Neanderthal DNA. Nevertheless, Neanderthals are considered a separate species.
  • Humans have much DNA in common with other animals and even plants – for example 20% with some plants, 40-50% with some insects, 60-90% with most animals, and almost 99% with great apes.

Difficulties for christians?

Understanding DNA has enabled breakthroughs in medical science, forensics and genealogy/paternity, so the science of DNA is well tested. It is hard to see how it can be wrong, though the calculation of some dates is sometimes problematic because the rates of mutations and change are not necessarily always constant.

This provides some interesting insights.

Evolution

If DNA similarities can demonstrate connections between our relatives, the same principles hold true for more distant relatives among animals. Thus DNA becomes a significant support for evolutionary science and the concept of common descent. Francis Collins says: “I would say we are as solid in claiming the truth of evolution as we are in claiming the truth of the germ theory.”

Obviously this is difficult for some christians, but it can be “food for thought” information that opens up new understandings. Just as the discoveries of Copernicus and others led to us seeing the earth-centred cosmology of the Old Testament as pictorial, so I believe we can allow the discoveries of DNA to amend interpretations of Biblical statements on species and the process and timing of creation.

Theology

But one thing leads to another. Accepting the DNA evidence for evolution in turn leads to other questions. How should christians understand Adam and Eve, original sin and the Fall? When did “human” life begin, and how do we differ from the great apes?

Christians have been grappling with these questions for a while, and there are varying answers. Many accept that Adam and Eve has to be seen as a myth – a story that God has used to teach a truth about the universe’s origins, if not the process of creation. Some think the doctrines of the Fall and original sin have to be modified similarly.

Perhaps most importantly, the difference between humans and other animals cannot be so much physical as spiritual.

Uncomfortable food for thought

Some christians are uncomfortable with this. They say the truths of God’s word cannot be subject to human interpretation. This whole question can lead some christians to give up their belief, while others hang on even more tightly to the form of belief they are familiar with.

But human interpretation is required for us to even have a Bible to read.

  • We don’t have an original text of either testament, and we only know the text because scholars have painstakingly compared the different documents available to us today and made decisions as best they can on which of variant texts is most likely to have been the original.
  • We can only understand the Old Testament, for example, because scholars have learned the Hebrew language and how to translate it from the original setting to ours. Some of their understanding comes from archaeology, anthropology, linguistics and history.

Therefore, I believe, we should see the Bible and nature as two different revelations of God, both meriting scientific, linguistic and cultural study, and both requiring interpretation and understanding which may be subject to change.

I believe there is no reason to refuse to accept these new understandings, and likewise no reason to give up belief in Jesus because of new understandings of the Old Testament – christian belief is based on the New Testament.

Arguments for God

But DNA isn’t only a challenge to christians – it also challenges non-believers.

Making DNA in the first place

The process by which DNA is used to replicate different cells is very complex

Proteins are complex molecules which make up about a third of most cells, and perform many important functions. Each protein is comprised of somewhere between a hundred and several thousand ‘amino acids’, each of which may be composed of about a dozen or more of mainly carbon, hydrogen, oxygen and nitrogen atoms. There are 20 different amino acids, half of which humans can make themselves, and half of which are obtained from food. The sequence of amino acids in a protein determine what function it will perform.

When a cell prepares to divide, the DNA splits into two strands, each of which is used to build a second strand and thus a second cell. Only part of the whole DNA sequence is relevant for each type of cell, and that sequence of information determines the characteristics of that cell, say hair colour if it is a hair cell. Enzymes (one type of protein) read the information in a DNA molecule and copy it into messenger ribonucleic acid, or mRNA. The code carried by the mRNA is used to construct the sequence of amino acids in the required protein molecule. Each group of three bases in the DNA sequence specifies a particular amino acid.

For life to begin in the first place (abiogenesis), this complex process had to evolve, something that is extremely difficult to believe happened by chance. Science has not yet established how it happened, despite a lot of attention being given to this research. Many christians believe this is an indication of when God intervened in the natural process to create life.

However christian biologists, such as those at Biologos, caution against this conclusion. It seems better to say that God created the universe in such a way that this evolution of life from non-life could occur “naturally”.

Nevertheless, the complexity of DNA and the difficulty of explaining how life with such complexity arose is a challenge to non-believers. It is truly amazing that life began at all.

The information contained in DNA

DNA stores an enormous amount of information, so much that it has been calculated that all the information in the world could be stored on a truckload of DNA. Information theory is the science and mathematics of information. It has been well developed and utilised in modern computing, and has been shown to be valid in considering DNA.

It can be argued that DNA is a code, a language, that encodes information, just like computer code, and that such information code has never occurred naturally, but always requires design. Therefore, it is argued, DNA points to a designer.

Non-believers disagree of course. They say that DNA isn’t a code, it is nothing like computer code, it is a molecule.

I must say I find the arguments on both sides a little self-serving – exactly what you’d expect each side to say. I don’t really know how to evaluate them. And I note that christian and science website Biologos counsels against assuming too much about genetic code and its origins.

But granted the amazing information properties of DNA, I think we can conclude that DNA presents a challenge to naturalism, and leave at that.

Conclusion

DNA is fundamental to all life. Any worldview needs to be able to account for it. Traditional christianity struggles with the evidence for human origins contained in DNA. Naturalism also struggles to explain how a mechanistic universe was “finely tuned” enough to allow life, and then to produce life of such complexity.

I think a more modern approach to christian theism explains the science of DNA best of all.

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Other references:

Photo Credit: ynse via Compfight cc

9 Comments

  1. Hi Eric,

    You said,
    “We can become quite “tribal” about our viewpoints, and defend even small differences quite vigorously.”
    And I think that’s often true, but for a reason. Here for instance, in this article, everything started great. It’s very well written. But, at the very end, you inserted some commentary on how both “sides” have difficulties, or struggles, with the meaning of DNA, or more broadly about fine tuning. This is simply untrue; neither in the more specific case, or broader view. And this is what can cause people to be more “tribal” about their beliefs, because it’s quite annoying to be “told” what we think: i.e to read some misinterpreted opinion regarding our own views. I, for one, find your approach to be, quite frankly, yet another example of your passive aggressive techniques to debating ideas YOU struggle with. Food for thought…

    Belated Merry Christmas by the way!

  2. Hi Hugo, merry Christmas to you too!

    Thanks for the compliments contained within your comment. I appreciate them. But I am slightly amazed and not so happy about your comment of “passive aggressive techniques”, and I guess not even really sure I understand what you mean.

    I write a blog, a weblog, which one website describes as a “diary-type commentary”. Like other blogs, it expresses my opinions about the things I am interested in. I try to base my ideas on established facts, but the selection of facts is based on my interests and perspectives.

    No-one is compelled to read my blog, though I am gratified when people do. But when they come here, I presume they (which includes you) understand what they are getting – the opinions of a christian who tries to be thoughtful. I can’t see how that can be passive aggressive.

    If you think I have described your views wrongly, then you are free to assume I wasn’t talking about you, or to correct me. But you haven’t done that. Instead you have offered your opinions on my views and psychology.

    So I am sorry I have annoyed you, but if you focus on my motivations rather than telling me what you think, you will be doing exactly what you accuse me of and leaving me still unaware of where you think I got it wrong.

    Perhaps we should re-wind?

  3. Hello,

    But I am slightly amazed and not so happy about your comment of “passive aggressive techniques”, and I guess not even really sure I understand what you mean. […] the opinions of a christian who tries to be thoughtful. I can’t see how that can be passive aggressive.

    Well, if you don’t understand, of course you cannot see it for what it is… The main thing you seem to forget here is that it’s not like I just randomly write on your blog for the first time and make that comment. This is the continuation of observations done over almost 2 years now; here on you blog and from at least 2 others where I saw your comments before reaching out here.

    The comment of passive-aggressive relates to your constant attempt at being nice, at wanting friendly and peaceful discourse, which is great, while simultaneously writing things like this: “ So I am sorry I have annoyed you.” No you are not; I don’t believe that for 1 second. That’s the very definition of what being passive-aggressive is.

    But then, there is also the bigger picture, where you look at your beliefs and see where they fit with the real world. When doing so, you also look at some worldviews you don’t believe in, such as naturalism, and show how you think they don’t fit. That’s when you claim open mindedness and tolerance for other views, only to misrepresent them and show them as just another opinion.

    For instance, in the current article, you said:” I must say I find the arguments on both sides a little self-serving – exactly what you’d expect each side to say. […] Traditional christianity struggles with the evidence for human origins contained in DNA. Naturalism also struggles to explain how a mechanistic universe was “finely tuned” enough to allow life, and then to produce life of such complexity.” But this is simply false. There is no struggle on the naturalism side because there is no such attempt at making grand metaphysical conclusions, which is religion’s business. There is also no struggle in this particular case because biology explains natural processes so well that there is no doubt, at all, that life evolved and diversify naturally. The study of biology has revealed the natural mechanisms by which life diversified on Earth, from simple beginnings to complex human beings. There are still lots of learning to do but nothing will ever make us doubt that life arose naturally. The complexity we see is 100% accounted for, by natural means, even if we don’t know all the details.

    The passive-aggressive aspect here is thus that you pretend that it’s opinions vs opinions, some sort of ‘well we don’t really know; both sides have points, so we each believe what we want to believe, isn’t it?’ But no, it is not the case. There are things that we know, collectively, and from which some conclusions follow, and from which we know some conclusions do ‘not’ follow.

    As for what you got wrong, specifically, I will give just 2 examples:

    (1) “ DNA stores an enormous amount of information, so much that it has been calculated that all the information in the world could be stored on a truckload of DNA.
    Not sure what ‘truckload’ means exactly but this is obviously false. Yes, DNA stores a lot of information but there is not just a lot of information in the world. With 3 million base pair, DNA can be stored entirely on a good old computer CD. I hope I don’t need to explain why a truckload of CDs would not be nearly enough to store ALL the information in the world. This might seem like a small detail but I think it matters a lot; because misunderstanding details like that makes it much likely to miss the big picture, especially when the error relates directly to the notion of how ‘extraordinary’ something is.

    (2) “ It can be argued that DNA is a code, a language, that encodes information, just like computer code, and that such information code has never occurred naturally, but always requires design. Therefore, it is argued, DNA points to a designer.
    Non-believers disagree of course. They say that DNA isn’t a code, it is nothing like computer code, it is a molecule.

    It’s not just a disagreement, and it has nothing to do with non-believers, this is a factual question. I would not go as far as saying that DNA is ‘nothing’ like a code (it can certainly ‘look like’ a code) but it is really just chemical reactions happening on their own, without nothing actually reading the code. The physical shape of the molecules processes during protein folding is what cause different results. Actual codes don’t work like that; you can re-create similar meaning words by using completely different letters, but you could not do that with proteins created via DNA nor with processes started/stopped by regulatory genes.

    you will be doing exactly what you accuse me of

    Yep, because I do it all the time myself, knowingly 🙂

  4. Hi Hugo, thanks for that explanation. I think that sets the scene well for a bit of a review of where we are at.

    First, I’m sorry, but I think your comments about passive aggressive are pretty much meaningless and mistaken. (1) You say you do it, so why criticise me? (2) In sum, it seems you think I behave too nicely to be saying things you disagree with. But I am genuinely a “nice” person who occasionally says dumb or unhelpful things, and I really do want to be as nice and friendly as I can. (3) You are wrong. I really am sorry if I have annoyed anyone. I try to be thoughtful, accurate, challenging and encouraging, but don’t always succeed. So I am going to put that topic aside and ignore it from now on. I appreciate what you have said, and I think it convinces me to take that course.

    Second, since you have outlined a few of your thoughts, I will outline a few of mine. The internet is full of arguments and argumentative people, including atheists, christians and those in between. I am not interested. Controversy is a good way to get hits on a blog, but I’m not interested. I walk away from argument rather than participate, because I think it is unproductive and contrary to my beliefs. As a christian I am commanded to love everyone, with “love” meaning work for the best for them rather than for myself. Again, I don’t always succeed, but that’s my aim.

    So I try to make my website interesting, informative and challenging without being argumentative, and specifically disallowing “insulting, rude, aggressive, aggravating, repetitive, silly or irrelevant, off-topic comments”. So far I’ve only had to ban one person and filter out a few nasty comments. I want to appeal to people who want to know what I have found or are interested in the same topics.

    But obviously I get other readers and other comments, and I address them in as friendly a manner as I can. You seem to be in that category. You disagree with me, you take exception to what I write and have even expressed that response in strong ways at times. Yet you continue to read and comment, and at times it seems that you only do it for the sake of an argument. That goes with the territory of having a blog, and I have said truthfully that you are always welcome to comment.

    But to me it seems a bit pointless. We know each others’ views and arguing about them hasn’t achieved much so far, especially if it leads to comments like passive aggressive, and some previous comments that led me to put you on moderation. My suggestion is that you continue to make comments as long as you are interested, but keep them briefer, focus more on stating your own view rather than arguing about mine, and don’t expect a long discussion. This isn’t an abstract idea, for it is exactly the response I have made on my favourite atheist blog.

    Now a brief comment on your critique of this post …

    “There is no struggle on the naturalism side because there is no such attempt at making grand metaphysical conclusions, which is religion’s business.”
    That is exactly what I mean. Naturalism cannot explain it and doesn’t try. If naturalists are happy with having no explanation, then that’s up to them. But I wouldn’t be happy with that for I think lack of explanation throws doubt on a worldview.

    Re DNA: I’ll certainly look into the information on a truck idea. Re code, your view reasonably sums up the naturalist view. But I was trying to briefly sum up both views.

    Best wishes.

  5. Hi Eric,

    Thanks in turn for the explanation, but I am not about just argumenting. I am actually pointing out flaws in the content where I see them, and wondering whether your opinion is based on false information, or despite the information.

    So let’s stick to the content:

    Naturalism cannot explain it and doesn’t try. If naturalists are happy with having no explanation, then that’s up to them. But I wouldn’t be happy with that for I think lack of explanation throws doubt on a worldview.

    You are essentially saying that it’s better to believe something, even without good reasons, rather than not believing because we don’t have any good reason to believe something. And even worse, you say that a worldview that does not explain something, which nobody knows about, is worse than a worldview that gives an explanation for no good reason. This is completely irrational, and afaik you are not that irrational, so what am I getting wrong?

    Re DNA: I’ll certainly look into the information on a truck idea.

    What is there to look? Human DNA has roughly 3 billion base pairs; a regular CD has ~700 MB of information, which means ~5 billion bits (700*1024*1024*8). I made a typo by saying ‘million’ instead of ‘billion’ by the way, but the difference does not even matter here…

    Re code, your view reasonably sums up the naturalist view. But I was trying to briefly sum up both views.

    But it’s not about a “view”… it’s a fact.

  6. Hi Hugo,

    “I am actually pointing out flaws in the content”

    That’s an admirable aim. Unfortunately …… You said my comment about DNA was “obviously false”. But if you check out this reference or several others like it, you’ll see it was right, and recently the amount of DNA required has got even smaller.

    Do you see why I think you don’t do much factual research before most of what you write?

    “You are essentially saying that it’s better to believe something, even without good reasons”

    Hugo if you honestly think that, why would I bother even answering? What you say here is nonsense. Perhaps you can think a little more about this and tell me the wrong assumption you made?

    I’ll leave it at that for now.

  7. Hi,

    1) “You said my comment about DNA was “obviously false”. But if you check out this reference or several others like it, you’ll see it was right, and recently the amount of DNA required has got even smaller.

    Yes, I was wrong on the count; completely. At the same time, I did say ‘not sure what a truckload means’ so that was also a question as to what this is supposed to imply exactly? So, again, my mistake on the exact number of DNA strands required to store all the information in the world; and I should instead ask you to clarify: what does it mean?

    To be clearer, the problem I saw in your article is that it implies that because DNA stores an enormous amount of information, it points to a designer, along with other reasons. But that 1 reason may not be as compelling when we realize the true amount of information stored on 1 molecule.

    2) I said “You are essentially saying that it’s better to believe something, even without good reasons” and you replied: “What you say here is nonsense.

    But I was asking you to clarify this:
    If naturalists are happy with having no explanation, then that’s up to them. But I wouldn’t be happy with that for I think lack of explanation throws doubt on a worldview.

    What does that mean then, if not ‘any explanation is better than no explanation’?

  8. Hugo, the detail about the amount of information DNA can store is minor, but your propensity to make confident statements beyond the information available, and sometimes against it (illustrated in this minor matter), is difficult for me to deal with. And I think you have done something similar with the second and more important matter of your assessment of what I am “essentially saying”.

    I don’t want to be cute, patronising, nasty, or anything else, but I see little point in continually correcting these mistakes, and then we get into an argument. So, as an exercise, why don’t you review what I said and then set out the various possible explanations you can see of what I said, and then we’ll see where that takes us?

    Thanks.

  9. Sure, taking a step back, looking at the post, and simplifying the points of contention here, it all boils down to this:

    But granted the amazing information properties of DNA, I think we can conclude that DNA presents a challenge to naturalism, and leave at that.
    […]
    Naturalism also struggles to explain how a mechanistic universe was “finely tuned” enough to allow life, and then to produce life of such complexity.

    There are 2 simple problems with this:
    1) Biology explains a lot; enough to know how DNA came to be the way it is. It’s not a mystery anymore, and thus not lacking natural scientific explanations; there is no struggle.
    2) But when there are sgruggles, whenever there are actual gaps, such as how the first self-replicating molecules came to be, it’s because we collectively don’t have an answer. The rational position is to acknowledge that.

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