Lignin: A Fun ID Puzzle

Faith & Science Conversation
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So I have read all of Doug Axe’s (ID proponent) scientific work over the last 6 months, and it has been a fun read. I think the most interesting article was this one about Lignin, a ubiquitous plant substance that is very difficult to digest despite being very energy rich:

http://www.bio-complexity.org/ojs/index.php/main/article/viewFile/BIO-C.2012.3/BIO-C.2012.3

Axe contends that (1) no efficient way exists to degrade lignin, (2) an efficient way to degrade lignin would totally disrupt the biosphere, and (3) given the 100s of millions of years evolution has had to evolve an efficient lignin degrading enzyme, this strong evidence that new functions are hard to evolve.

For those that do not want to read the original paper, here is a brief summary and talk…

Lignin provides a paradoxical case for the Darwinian method of evolution, but fits perfectly into a design oriented scientific paradigm. Thirty percent of non-fossil organic carbon on the planet is lignin, so in a Darwinian world, something should have developed the ability to consume lignin–but it hasn’t. Lignin binds together and protects plant cellulose, which is vital to all types of large plant life; “The peculiar properties of lignin therefore make perfect sense when seen as part of a coherent design for the entire ecosystem of our planet.”

Now, of course, I do not agree with this logic and think the scientific claims end up being wrong. But I thought I’d open up the conversation here. I think the science is really interesting, and it will be fun to discuss with everyone here.

What do you guys think?

@deliberateresult @glipsnort @Eddie @Jon_Garvey @Jonathan_Burke @Jay313

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Well first impressions on reading the paper is that he states that no micro organisms break down lignin, but then in the paper he says that fungi do, so I have a little problem with that.
As to why it is not a food source for a wide variety of organisms, perhaps it is because it has been well evolved to resist them, and further is always associated with cellulose, which is easier to break down, and thus there would be no driving force to use it as a food source since always associated with an abundant and more easily utilized alternative.
I look forward to hearing from our more learned forum commenters.

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It is my understanding that lignin is a structural carbohydrate that binds other nutrients. That is why shorter grass provides more nutrients to grazing animals than taller grass–because tall grass has more lignin (used to support a growing plant).

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My first thought is that if ID is true, why is it that they have to scrabble around for just a tiny handful of organisms which allegedly fit “perfectly int o a design oriented scientific paradigm”. If ID is true they should be absolutely spoiled for choice, and not restricted to organisms.

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So why aren’t humans designed to be ruminants? There would be a lot less starvation. We could make hay while the sun shines, and then eat the hay.

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I think this gets back to the fact that IDers don’t do science.

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ID says life is too perfect not to have been designed by a creator… but they have nothing to say about all the parts of the Universe that is poorly conceived.

Arguing that Evolution is false because it can’t produce some kinds of genetic features is quite the stretch! … much like me arguing that the Bible must be wrong if it can’t be clear about the moon orbiting the Earth, and the Earth orbiting the Sun!

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Joshua

The trouble with this kind of thread on BioLogos is that (as here) very little science ends up being discussed, but instead plenty of stuff about ID not being science, the usual Dawkinsesque claims that the universe is badly designed (ergo, George, evolutiuon is not directed by God), trope, meme, etc.

I confess I find that tedious, rather than fun, or even illuminating.

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Lignin is ubiquitous and is found in plants, trees etc. - deposits of low-rank coals are usually termed lignite, because it is believed they are the products of degradation of forests in swampy environments. The conversion into these coals is poorly understood, but it is worth noting that lignite and subbituminous coal deposits form about half of all coal on earth, so an awful lot of lignin has been degraded (or converted) into these fossil fuels.

The molecular structure of lignin is another fascinating example in nature - it is thought to form a helix and this (and other aspects) enables it to impart strength to trees, and other vegetation.

I will not add more information - I confess I cannot see how anyone can make a case for evolution, or ID, or any other such outlook, based on lignin. If we look at the molecular and cellular details of trees and plants, we observe additionally fascinating and intricate features that would evoke praise to the Creator - however these features, from what I understand, do little for ToE or ID (I would add that the arrangement observed would evoke thoughts of fantastic design, and I do not think any human can replicate or even copy many of the features, but this argument is mainly aesthetic and not ID).

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I see your point. That wasn’t my intention =/. I honestly found the science in this one interesting. Perhaps this post was misguided.

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There are good reasons why a number of those issues keep coming up. But there’s plenty of science in this thread, have at it by all means.

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Thanks for another invitation!

I think it would be even more fun if you invited dr. Axe as well

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Okay,

Let’s try and get this back on track. Axe’s argument emphasizes a few points. His key question is:

How can microorganisms have failed
to exploit lignin as an energy source while much less evolvable species
have, on innumerable occasions, acquired solutions to problems
that appear to be considerably harder?

In my view, this is a very valid and interesting scientific question. I applaud him for raising it. It pointed me in the direction of a lot of really great reading that usually only a plant scientist like @sbodbyl would read.

Somehow missing this literature, Axe’s conclusion is that there is no good reason within the evolutionary paradigm,.

Perhaps the oddest aspect of this is that Darwin’s theory is
unable to make sense of a situation that otherwise makes perfect
sense.

and then writes.

A mechanism that leaves low-hanging fruit unpicked can hardly
explain how so much high fruit has been picked.

In my view, this is an argument that relies on gaps in scientific knowledge, because it depends on there (1) not being an organism with specified characteristics, which we can never be sure of because we only know a tiny fraction of microbes, and (2) that there is not a good evolutionary explanation, which he does not attempt to make. But, rather than going down the ID or anti-ID polemics, there are two fundamental scientific questions at play.

  1. Is it really true that no organism uses lignin as an energy source?

  2. Is lignin degradation really low hanging fruit? Why would lignin degradation be so difficult? Or why would we see the current situation we see in nature?

For #1, before you point to white rot as the answer to the puzzle, Axe argues that white rot fungi do not use lignin as an energy source and there is one very limited experiment that supports him here. Despite the shaky foundation, he may be right.

I’ll encourage you that the answers are really interesting and easy to find with pubmed searchers (from the free abstracts if you can’t get past paywalls). Of course, if you can get the full articles, it is even more interesting.

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You can feel free invite him =).

He is more than welcome here, but I am doubtful he will want to participate. You can invite your ID friends too. We would love to hear their thoughtful responses. Maybe even @vjtorley will show up.

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@Jonathan_Burke

At the risk of extending the tedium just a little bit more - - for the sake of clarity - - I need to point out that my position is:

  1. God does guide Evolution (including or especially the difficult parts).
  2. But there is enough badly designed aspects of the Universe to put a limit on the assertions of
    Intelligent Design - - there is not enough evidence to prove Intelligent Design, but there is enough
    evidence to prove that Intelligent Design isn’t Intelligent all the way through Creaiton!

Ergo: An Old Earth scenario, requiring millions of years of mostly the operation of natural law.

The tedium comes from constantly trying to wedge Intelligent Design into a dominant position over natural lawfulness … when clearly it doesn’t have enough consistency for that role or status.

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Hmm. The old Deists believed that the wisdom of God was shown in that the goodness of God’s creation of “all things in heaven and earth, visible and invisible” (Nicene Creed) was achieved by the good laws he set up to achieve it. A very hands off God, in terms of classical Christianity, but the Creation at least was consistent with biblical monotheism in its goodness.

So when and where did the idea come in that the laws, except in unspecified instances where God corrected things by hand, were prone to creating “badly designed” things, implying that they weren’t quite so wise as all that, and in fact rather lawless?

I don’t like Deism, but I don’t like the new dualistic Creation even more. Apart from anything else, the division of labour between clever God and stupid nature is always entirely subjective.

“Evolutionary Creation holds that evolution is the means that God used to create living things, when natural law wasn’t hogging it.” Discuss.

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This is not a scientific issue per se. It’s a philosophical one of basic epistemology.

The authors write:

The paradox vanishes completely when we adopt a design perspective.

…and resurrect Dr. Pangloss. All problems seem to disappear when one invokes outside agency. The authors suggest, ‘design-wise’, that rapid breakdown of lignin would prevent the generation of some soils. OK. But why are those soils specifically required? Terrestrial life existed before those. More importantly, why did the designer require soils of that composition and why did the designer have to introduce those components via hardwoods which would later decay? Why lignin specifically and not some other chemical complex?

On the flip side, why not instead suggest that the designer actually intended this so that humans would have coal to heat their houses and support an industrial revolution? The issue with ‘design perspectives’ are the difficulties in producing concrete, specific explanations instead of Panglossian stories. Exactly how does one demonstrate design via negative arguments of what is absent or present today?

Here’s a positive argument to make: It seems that Axe et al. have set up the case that it should be biologically possible to design rapid lignin degradation mechanisms in living organisms, even if ‘Darwinian evolution’ has not yet done this. That sounds like something they would need to demonstrate in order to support their point. Take a set of enzymatic mechanisms as a particular starting condition and show how lignin degradation could be developed by a designer.

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I am not a biologist, but from what I have looked up on what lignin does, anything that could eat lignin would destroy all tall plants, and therefore put itself out of a food source. This would seem to put strong evolutionary pressure against anything developing that could eat lignin.

Modern wood contains 25% lignin and 45% cellulose, so there would be advantages for animals to develop the ability to digest cellulose. If lignin turns out to be undigestible, it would add bulk to the diet of cellulose eaters. Creatures that ate cellulose plus lignin would die of constipation, also putting evolutionary pressure against evolving the ability to digest lignin.

Every evolutionary change that provides an advantage of some sort seems to create a problem of some other sort, so evolutionary changes always come at a price. The price of digesting lignin seems to be too high so far.

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Which is fine. We have a lot of scientific posts for those so inclined, so throwing a bone to the rest of us is nice. I will stand by my observation that there is really no reason to develop a means to digest lignin so long as cellulose is abundant. It would be interesting to know whether the fungus that leaf cutting ants cultivate can digest lignin, but again it would be unnecessary since they have abundant cellulose available, and without a shortage, they would have no reason to develop that capacity.

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I don’t think those scenarios would block the evolutionary development of lignin digestion. There are microbial mechanisms that can manage lignin catabolism. They just cannot operate terribly fast.

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