Head-Desk Embryological Stupidity

As a High-School Biology student in New Zealand, I am not required to know anything about embryology. And so, for the most part, I don’t. In the circumstances it seems that I am far from the only one.

Brian Thomas’ latest article on the Institute for Creation Research’s Daily (pseudo)Science Updates page is called Evolutionary Paradox: Embryos Resist Tinkering. From my experience over the last few months, Mr Thomas has two main ‘arguments’ on the subject of embryology: The first is that DNA is somehow not enough to explain the processes involved – for example in The Theory of Supernatural Embryology?, More Fruit Fly Larvae and the earlier Amber and Embryos – and that all mutations in the instructions for embryo development are lethal or close to – such as in Genetic Stop Sign Halts Evolutionary Explanations. This latest post belongs with the latter. Snails are related this time, rather than being entirely Drosophila related as is more usual, hence the following picture:

Apple snail eggs Continue reading

Genetic Stop Sign Halts Evolutionary Explanations (DpSU)

Soo… If you genetically modify the good ol’ fruit fly, Drosophila melanogaster, to remove a presumed-redundant genetic ‘stop signal’ at one of the many places in the fly’s genome where there are double ups, you don’t get a very happy fly. Also, this disproves evolution. hmm…

You may have noticed that Mr Thomas has two default templates for his news articles. In the first – such as the baby tyrannosaur news item I covered at the end of this post, or the Io post – he takes a legitimate news piece and/or scientific study, and uses that as a launch pad to talk about something only vaguely related, usually something he claims ‘evolutionists’ cannot yet explain. Alternatively, in a post like this, he takes the study and reinterprets it to back up creationist ideas.

In this article, Thomas also talks about “a study published in 1980, [where] core fruit fly genes were altered, one by one, and the resulting plethora of dead flies proved that there was no “wiggle room” to add the mutations that evolution would require.” The 1980 study can be freely downloaded here, while the new one will require a subscription to Nature (which I don’t have, btw). When referring to the study Thomas links to an article here on the subject, if you want to read along.

The 1980 study deals specifically with mutations that affect “segment number and polarity in Drosophilia“. I would contend that tinkering with such genes is like randomly playing with the foundations of a house that’s already been built. Especially since all the mutations involve the removing of segments. As a general rule, major changes in the body plan of animals are rare, for the reason that other things have been built on top of this and rely on it to work, otherwise they become harmful. You can’t give a cat six legs – at the very least you’ll stuff up it’s finely evolved balance. It shouldn’t be unexpected that such mutations would be largely detrimental – evolution doesn’t progress in such large stages all at once.

As for the new study, this doesn’t really support Mr Thomas’ conclusions either. As I mentioned (to quote from the article on the study) “the majority of genes have more than one stop-signal” which looks at first to be redundant and useless. That we can show that there is a strong reason for this doesn’t mean that the organism cannot evolve. Basically, Thomas does not succeed in backing up his conclusions:

First, in addition to the raw code for proteins carried in the gene, this particular stop sequence is also required for any fruit fly to survive. In other words, the genes plus the regulatory DNA comprise an all-or-nothing system that defies evolutionary ideas of the fruit fly being the product of a gradual accretion of its parts.

Moreira said that both full stop signs are required for “effective regulation of the levels of the resulting proteins.”2 The correct numbers of proteins must be expressed during embryonic development.

Second, this result adds to an ever-growing list of regulatory DNA sequences that do not code for proteins but are nevertheless vital. It appears that a vast majority of any organism’s genome is highly regulated, tightly packed with information (often double-layered), and therefore unable to tolerate many mutations without breaking down.3

Citation 2 is from the alphagalileo.org article I linked to above, while 3 is from one of Thomas’ own articles, which is surprising as it seems to be related to Junk DNA, a common subject in the ID community at the moment, for some reason. There are therefore plenty of better places to cite for this important statement.

In summary, what Thomas is saying is that Fruit Fly genome is such that further modifications cannot be made by evolution as all mutations are detrimental. He is also extending this into the past, effectively claiming that the D. melanogaster genome is Irreducibly Complex. This is again a dangerously large example if IC – there could easily be a simpler form, considering what we know from the two studies. A lot of research has been done on D. melanogaster, and I don’t know if there has been other studies showing places where you can mutate the fly to get surviving offspring. I have a hunch though, that there have been documented cases of this.

So, Thomas is trying to show that “the removal of this one fly “stop sign” demonstrates that the whole fly must also have been purposefully engineered.” He doesn’t manage it. All we have is a study that shows it’s not possible to remove segments from the fly willy-nilly, while the other shows that a common feature of genes is infact useful, as you would expect. More evidence is needed to “prove that there [is] no “wiggle room” to add the mutations that evolution would require”. Until then…

Amber and Embryos – DpSU’s, May 30

There have been some rather amusing articles from Mr Thomas in the last few days…

To summarise the first, a CT scan of a 49 million year old spider trapped in amber (video) apparently challenges evolution, largely on the grounds that

  1. The spider’s relatives haven’t noticeably changed over the millennia, and
  2. The amber has rapidly oxidised and turned opaque since being found in 1854 – how can it have been 49 million years old?
  3. The Baltic Amber was caused by the Flood, as “a large deposit [of amber, such as in the Baltic,] implies massive damage to whole forests that was catastrophic enough to trap even “strong, quick animals.” This kind of broad-scale destruction is consistent with the global Flood or its residual catastrophes.”

The first is interesting – how much can you expect the surface of a spider to change over a few millennia, compared to another spider in the same genus? Considering, you understand, that you can’t see the colour and the specimen isn’t complete in all respects. I dunno myself, but I doubt it’s that much. As time passes, major changes in organism groups are decreasingly common, and spiders had been around for nearly 200 million years when the amber here was made. Thomas tried to make a similar argument not too long ago, when he claimed that horsetails hadn’t evolved much since the time of the dinosaurs (150 million years ago, in this case). Again, this isn’t unbelievable. What would be useful here is DNA for comparison, and despite what you might have seen on Jurrassic Park this is unfortunately not possible for either the horsetail or the spider specimen. This hardly “Confirms Creation”. It is also worth noting that the whole “Punctuated Evolution” saga is over the degree to which evolution occurs in bursts, nobody feels that evolution occurs “relentlessly”, even if more the most part mutations do.

As for the second, this is claimed to be a killing blow but in reality is glossed over somewhat. Thomas claims that “there are no known rock types that are able to totally block oxygen from passing through them”, which may well be true, but I wouldn’t be surprised if the amount (or lack of) oxygen is sufficient to slow the rate of oxidation by orders of magnitude. Considering that it still took 150 or so years to turn opaque while out in the air, how long would it take under anaerobic conditions? Probably quite a while, I think. Tellingly, a section of a paper that I am unable to access states that “The high content of organic matter in the sediments [which sediments I don’t know] favours the preservation of amber by preventing its oxidation and destruction. Otherwise, in aerobic conditions, during pre-transport exposure to the atmosphere or reworking processes, amber oxidation takes place quickly”. Interesting…

The Flood reference seems a little out of place, or at least poorly backed up. It may well be true that amber appears as a result of catastrophe, but I can’t see how this could be caused by “the global Flood or its residual catastrophes”, the nature of which are not specified by Thomas or the Bible as far as I am aware. Indeed, Thomas provides no challenge to the dating of the amber at 49 million years, nor the insects in other pieces of amber, which are indeed different to their present forms.

As for the second, “Embryonic Tissue Development Needs More than Just DNA“, therefore God. Something like that, anyway…

I can’t claim to be an expert in this (or anything else), so I’ll take it that Thomas has faithfully reported the study that he is using for a source, and is merely adding his own interpretation. What he is claiming the study shows that if you stimulate muscle contractions in roundworms with a needle, you can cause stem cells to differentiate into epithelial cells. Fair enough, but then Thomas goes on to claim that this means that not all embryonic development is caused by DNA, and even further as to say that:

…the fact that specific elements other than DNA—in this case, nearby cells and their contractile motions—are required for proper development removes evolution from contention as a possible origins hypothesis, since evolution supposedly operates by making changes to DNA.[ref to own article] So if something other than DNA is needed to develop and sustain life forms, then evolution is out.

So, what causes these contractions in nature? (I’m assuming they do occur in nature, though it doesn’t necessarily follow). It’s possible that it comes back to DNA. Even if not, Thomas is attacking a straw man of evolution, in which DNA is the only agent of heredity. It doesn’t have to be – Darwin sure didn’t know about DNA or genes, and anything that permits “descent with modification” can be incorporated into the system. After all, why wouldn’t it be? Imagine, for a moment, that we’re talking mammals instead of minute invertebrates, and that the cause of the muscle contractions is the precise chemical composition of the fluids in the womb. Most likely, the make-up of this fluid is determined by the mother’s genes – evolution can still occur. If it comes from the food she eats, that is still determined by genes. Hypothetically it could come from an approximate synthesis of the fluid the mother experienced in the womb herself, but even here evolution can still occur, although DNA is no longer involved to such a degree. Mistakes can still be made, and Natural Selection can still punish them. Thomas needs to show that the only possible explanation of the roundworm muscle contractions is divine – Evolution can still act on anything else, except possibly direct environmental influence, but if this was generally harmful to the organism, it can be evolved away from, or if not the species will simply die off. Will he do it? Lets see…

…He doesn’t. Instead he goes off on a tangent with a dangerously large example of irreducible complexity. I.C is usually invoked for the very small, such as bacterial flagella, not for things as large as roundworms and other multicellular creatures, as it makes it more plausible that the arch really would collapse if one stone was removed. This makes it even more likely that this, like most – if not all – other examples of I.C. raised over the years, simply isn’t irreducibly complex. I couldn’t tell you if that was the case, however, so I’ll assume that the situation is indeed I.C. It would seem likely, then, that instead of a simpler origin to the situation, it began (or at least went through a period of being) far more complex, inefficient and redundant. As time and evolution passed, it became simpler and simpler until it could do so no more, like a mountain eroded down to a single, beautiful rock. As a result, it fits the definition of ‘irreducibly complex’, but has still evolved. As you would expect, Thomas does not mention this, and merely finishes thusly:

So, what does it take to make epithelial tissue in roundworms, and possibly in other creatures? The answer is: precisely the right DNA, the right hemidesmosomes, the right kinds of nearby muscle cells, and the right strength and duration of muscle contractions. Without all these features already in place and fine-tuned to work together, there would be no epithelial tissue, and as a result, no surviving creature.

Skin development could not have evolved by a gradual addition of traits, because this would require a version of the animal that did not already have all the required traits. Such a transitional form would have died, and the animal would not exist today. And since it certainly exists, it must have been created.

*sigh* And to think I thought irreducible complexity was dead…