Rearguard action

File:BU Bio.jpgHow could amphibians become reptiles, or egg-laying mammals become marsupials, or small shrew-like creatures become ruminants and carnivores? Evolution is the simple answer, and the mechanisms are being worked out. But not all the mechanisms are absolutely clear, and this is a way to attack “neo-Darwinism”.

Here is a New York Times article from 2007. Darwin proposed “natural selection” as a way for species to change between generations: the best adapted creatures survived and procreated, the less adapted creatures did not. Since Darwin, understanding has grown about how genes may mutate producing physical changes.

Concerns about the sources of evolutionary innovation and discoveries about how DNA evolves have led some to propose that mutations, not selection, drive much of evolution, or at least the main episodes of innovation, like the origin of major animal groups, including vertebrates.

https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Branchiostoma_lanceolatum.jpg/303px-Branchiostoma_lanceolatum.jpgHow much can we generalise from particular observations? The NYT article expresses some of the questions scientists debate. I would read it and move on. But in November, Evolution News discovered this article and fell on it with delight, finding inklings of heresy on Darwinian evolution.

Um. The general idea holds, and more observations are made, and there is disagreement on how to interpret those observations. This is not “heresy”, a deviation from Revealed truth, but new knowledge, filling in the gaps.

Evolution News has two attacks on Darwinism which it backs up from the article. The first is Uniformitarianism: does evolution work, now, in the same way it did in the Cambrian? The NYT says how there is a network of genes which builds the gut in starfish. Most can be altered and the embryo compensates, but there are five which cannot be modified: change one, and no embryo forms. There is no reason to suppose these five did not evolve normally, but once they have evolved they lock evolution on a certain path.

SandstarThere is a sudden change in the Cambrian from animals which absorb food through the skin to animals which form a tube through which food passes from mouth to anus. Thereafter, all descendants are tubes. Change back ceases to be an evolutionary option. Evolution News pushes this too far, claiming animals in the past developed in a manner entirely unlike anything in our present-day experience.

The second is abrupt changes in body plans. Evolution News misses out the information from the NYT that a complex eye may evolve from a simple eyespot in a few hundred thousand years. Twenty million years to evolve a spinal cord seems less unlikely. Thereafter, chordates- mammals, reptiles, amphibians, fish- cannot lose it.

After a study involving Wikipedia over two hours, I have established that Evolution News manages to crow that evolutionary biologists cannot explain how animal body plans arose unless they reject what scientific experiments have taught us about how organisms develop only by missing out relevant information and conflating distinct matters. “Not all the work has been done” says the scientist. “We disagree about certain issues.” “Ha! Evolution is Wrong!” shouts Evolution News, capering joyously.

6 thoughts on “Rearguard action

  1. Hmmmm! Thanks for this thoughtful analysis. Most interesting. It is a pity that both sides in the debate seem to feel the need to better the other. The distinction whether something positively mutates, for example, or whether it selects away, may be rather fine, at times not at all clear cut. Rather like the sound of music, and the spaces of silence between the notes.

    Wonderful, thoughtful writing. Bless you! :-))

    Like

    • I am not sure there are sides in a debate, here. One group walls themselves up shouting “we’re right and everyone else is wrong” while others just ignore them. The problem for me is that the creationists claim to be Christian, which demeans Christianity.

      Like

      • Are we demeaned by what other people think about what we believe? Or does our state of allowing accept when there are things we cannot change? It is the same debate to be had about peace, war, honesty…. XX :-))

        Like

        • I care, because I find Christianity beautiful, and Creationism makes it look squalid and ridiculous. I care, so I write: with social media, I am part of many discussions, and so have measurable influence. No, I won’t get The Dishonesty Institute to shut down, but I might make one person move, slightly.

          I see Creationist sites and feel disgust and anger, because I can never quite believe how bad they are- and then, in between, I accept. The time to care is when I am doing something, or building up to doing something; other times, caring is just a burden.

          Like

  2. There are no sides to the debate; evolution is a proven fact. It has been observed both in nature and under laboratory conditions. It is about time some people got used to that.

    It’s just like an article I read recently in Huff Post declaring that the majority of US citizens do not believe in evolution while the minority do. I don’t believe in evolution – there is evidence enough to prove it as a fact. As such, that does not require any faith to believe in it. If I were to say “I believe in evolution.” I may as well say “I believe in the road outside my street.”

    I think many creationists completely misunderstand the Darwinian model of evolution. True, there does not seem to often be an option to change back, which it seems many creationists see evolution as an ever-upward spiral, when it is not. That in fact is closer to Lamarckism, which is the popular belief in Russia (and completely wrong). ‘Devolution’ can in fact happen and has indeed done so. The very fact that we no longer have the long arms and tails which enabled our ancestors to climb trees can be seen as such a change.

    This however is by no means a retrograde step. It is merely change, which is precisely how the Darwinian model works; by species adapting to their environments. Those best suited to any given environment will survive, whilst others will die. Yet this ‘survival of the fittest’ does not mean the better suited species is somehow superior to that which is not, it is just different. This was very apparent to Patrick Matthew of Gowrie, a tree hybridiser from the Carse of Gowrie (between Perth and Dundee), who observing such changes among tree species, wrote of them in a paper “On Naval Timber and Arboriculture” in 1829, and thus became the first person to explain natural selection, almost 30 years before Darwin set foot on The Beagle.

    Like

    • Darwin did work the theory out more completely than Matthew. From the quotes there, it appears Matthew found natural selection Providential: would that creationists now agreed.

      Humans also have the remnants of the third eyelid, which is translucent: you see it in the inner corner of your eye, but it can no longer move across. It was no longer particularly useful for survival. But we cannot develop in the womb without a gut or spinal cord.

      Christianity would be a great deal less repulsive without the antics of the creationists and ex-gays. Any controversy and up they jump, shouting that Evolution Cannot Work. I need an explanation of Uniformitarians from anywhere but a creationist site. Oh: here it is.

      The dishonesty of this particular Creationist article is to say that if evolutionary processes are not uniform, then we cannot know how they worked. But we have the general idea: genetic mutation. Protozoa had to evolve acceptable ways of mutating.

      Like

All comments welcome.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.