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Front Loading?! Say it isn’t so!

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Scientists have now found that the Hox genes necessary for tetrapod development is present in a primitive fish (a paddlefish). Here’s part of what they write:

“Tetrapods have a second phase of Hox gene expression that happens later in development. During this second phase, hands and feet develop. Although this second phase is not known in zebrafish, the scientists found that it is present in paddlefish, which reveals that a pattern of gene activity long thought to be unique to vertebrates with hands and feet is in fact much more primitive.

This is the first molecular support for the theory that the genes to help make fingers and toes have been around for a long time—well before the 375-million-year-old Tiktaalik roseae, the newly found species discovered in 2004 by Shubin and colleagues. Tiktaalik provided a missing evolutionary link between fish and tetrapods and was among the first creatures that walked out of water onto land.” (Taken from PhysOrg.com. Here’s the link.)

Poor old Tiktaalik roseae! It’s fifteen minutes of fame is over. So much for “a missing evolutionary link”.

Thank you all for your responses to my question. It seems that front end loading means different things to different people with the main difference being the taxonomic level at which it is believed to have occurred. So depending on what you believe about that, common descent could refer to the descent of all living things from a single (or three, or five?) original organism(s) or it could refer to the descent of all members of, say, a particular family (say, Canidae) from an original ancestral pair. The latter idea seems to be favoured by YECers working on baraminology. I must say that I find it very hard to believe that front loading into a single ancestral organism could account for the characteristics of all members of a kingdom. It just strikes me that such an organism would have had to have so many suppressor genes that its genome would have been very much larger than the combined genomes of all its descendant kinds. (Imagine a passenger vehicle with all the characteristics of every kind of passenger vehicle! It wouldn't be able to go anywhere.) But that's just an argument from incredulity and ignorance. Janice
Dinosaur proto-feathers falsified: http://www.pubs.royalsoc.ac.uk/media/proceedings_b/RSPB20070352.pdf Fossil shows birds evolved before dinosaurs http://www.abc.net.au/science/news/stories/s142745.htm Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16217748&dopt=Citation MatthewTan
"I ask because I have the impression that there are people who comment here who accept intelligent design but still believe in common descent" You are correct. mike1962
Front loading is an inchoate hypothesis of what might actually exist in genomes. I would say that stem cells bring out this notion that genetic information can be both present, and not expressed---a notion that ties into front loading. Whole-genome analysis across populations and taxonomic groups is needed before one can elevate front-loading to a principle from an hypothesis. We'll just have to wait and see. PaV
G Robinson: The poodle is still a savage killer at heart! A Far Side cartoon I found years ago had a funny take on "dog evolution" potentialities. "POODLES of the SERENGETI!" was the caption, and in the frame showed dozens of savage French poodles devouring a wildebeest and chasing off hyenas and other scavengers. Really a hoot. And yet it could happen. Anyway, I thought it was funny... Sorta a funny take on a Discover Magazine front page I saw one time to the effect that "Man's Best Friend: they've been evolving for 12,000 years". To which it looks more like NO--they've been BRED for 12,000 years. Breeding involves purposeful selection for traits like elongation (weiner dogs!) or agressiveness (German Shepherd), etc, etc. The point in this thread being that front-end loading is certain creatures (so far, maybe more to come) have a genetic base that allows for future transformation? And what is your answer going to be when the committed Darwinists say "welcome on board, regardless of the details, and by the way, these genes are like an alphanumeric keyboard or a Rubics Cube. The characters and positions themselves number 36 for the keyboard and 6 sides of 9 for each side of the cube, but the COMBINATIONS are virtually limitless. Every character EVER written in every scientific journal, every blog, every website like UD, and every hard copy paper used merely 37 characters, give or take a few exotic needs for mathematical equations. That's it. So is Front End Loading then more like adult or embryonic stem cells, which show pluripotent potentiality of combinations that are preset--or a loose arrangement of genes that can do anything if required? S Wakefield Tolbert
I ask because I have the impression that there are people who comment here who accept intelligent design but still believe in common descent.
I would suggest that this is the majority view of IDers on this site. At least the majority considers common descent as a serious possibility. I, for one, have become quite convinced of common descent, yet I am definitely an IDer. As far as the front-loading hypothesis goes, well, I think you will find a range of views. The most extreme view (knowing Davison, you would expect no less) is Dr. Davison's "Prescribed Evolutionary Hypothesis." He suggests that one, or at most three (one for each domain) organisms were designed. They were designed to produce the tree of life that we know, just as an acorn knows how to produce an oak. Others take a softer view of front-loading, seeing front-loading any time the evidence points to anticipatory biological constructs. Random variation and natural selection cannot envision the usefulness of, say, a limb. Why then would the hox genes necessary to make limbs preceed the development of limbs. Seems amazingly fortuitous to me. This would be a prime example of loose front-loading. Evidence for anticipation, is evidence for intelligent design. I remember watching a Startreck TNG episode where they ended up on some planet that had flying robots that shot at them. When the robots learned their patterns and began to anticipate their next shot, they took the "anticipation" as proof of intelligence. Naturalistic evolution cannot withstand it. bFast
An example I like to think of is that wolves already had the info for my choc. lab. It had genes for being a friendly, loving, retrieving, water-loving family pet. And wolves already had poodle genes, etc. geoffrobinson
Janice: "I ask because I have the impression that there are people who comment here who accept intelligent design but still believe in common descent." Front loading, roughly, is the idea that all the information needed for life forms is already contained in the genome, and that over time, given certain environmental conditions and changes to the genome through recombination and such, new morphologies appear. So it is consistent with common descent. I agree that as we understand the genome of animals better, and as we understand genetic networking better, that a fuller, clearer understanding of the feasibility of Darwinian evolution, versus such ideas as "front loading", will emerge. PaV
Thanks, but that's not specific enough. Janice
Frontloading is roughly the concept of putting info needed for later upfront in the genome. geoffrobinson
What is meant by 'front loading'? Does it refer to some design event involving a single organism or multiple organisms? I ask because I have the impression that there are people who comment here who accept intelligent design but still believe in common descent. So I guess I'm asking whether these folk believe in common descent from a single, intelligently designed organism or from multiple, differently designed organisms. I also ask because I've been reading around on hox genes and while my understanding of what they do is limited it does strike me that they could be working in a way roughly analagous to, maybe, the first stages of the production line of factories that produce conceptually similar products of varying final complexity or sophistication. For instance, there are certain rules to be followed if you want to create a vehicle that can carry one or more passengers from one point to another. At a minimum you need a directionally oriented framework of some sort and you also need seat(s), wheel(s), headlight(s), brake(s) and a steering mechanism. To make a bicycle takes fewer steps than to make a bus or a plane. As far as I can see, simpler organisms have fewer hox genes than do human beings but human beings, despite their complexity, still need eyes, limbs, mouthparts and so on. Maybe, once the way hox genes work is fully elucidated, we will be able to derive a set of biochemical rules for building at least the basic body plan of a living organism. Maybe it will turn out to be a set of 'if x then y' feedback rules. Maybe it will even turn out to be capable of being reduced to mathematics. Once we know the rules then we might discover why phase 2 expression of hox genes is necessary in the paddlefish but not in the much smaller zebrafish and why some forms of segmentation gives humans arms and legs and fingers and toes but gives fish fins. Who knows? How hox genes are expressed could turn out to be yet another manifestation of irreducible complexity. Janice
'"Here's something we thought was invented from scratch, but it was there in a deep ancestor of tetrapods," says Sean Carroll, a developmental biologist at the University of Wisconsin, Madison.' Quote taken from: http://www.newscientist.com/article/mg19426053.600-ancient-gene-kit-came-in-handy-for-limbs.html PaV
The evidence in support of the primitive feathers lacked serious investigation...
Imagine that.
bFast: What I'm a little concerned about, though, is that it looks like the guys who found Tiktaalik in the first place are the very ones who have done this study. In their minds, at least, they might find this as confirming that Tiktaalik is a true intermediate form. This can't be ruled out exactly since the paddlefish and Tiktaalik seem to overlap in the fossil record, with the paddlefish---presumably, since it is a 'primitive fish'---antedating Tiktaalik. From the information they've given us, however, it seems to me that the capacity for limbs was already genetically present in the 'primitive' paddlefish, and, so, anticipates anything that NS could have fashioned. To speak of the environment "triggering" the expression of something that is already genetically present strikes me as what, more or less, one would expect from "front loading". But the authors seem to talk about this, and never skip a beat. But, of course, there were those epicycles in Ptolemaic theory.... :) PaV
Off topic, needs a topic. 'Seem that dinosaur feathers is a myth: http://www.physorg.com/news99114780.html bFast
VERY cool find PaV. The front-loading gurus at TelicThoughts.com need to bash this one about. At first glance it certainly seems to be another big piece of the puzzle that calls for forethought on the part of the genetic engineer. As we know, RM+NS is not capable of forethought. bFast
[...] New genetic data overturn long-held theory of limb development Long before animals with limbs (tetrapods) came onto the scene about 365 million years ago, fish already possessed the genes associated with helping to grow hands and feet (autopods) report University of Chicago researchers in the May 24, 2007, issue of Nature. Sarcastic mockery at UD This finding overturns a long-held, but much-debated, theory that limb acquisition was a novel evolutionary event, requiring the descendents of lobed-fin fish to dramatically alter their genes to adapt their bodies to their new environments of streams and swamps. [...] Darwiniana » Fish with tetrapod genes
Interesting article, but I'd wait for more research on the topic before jumping on it. I hope it does promote research and discussion on the topic. Either way, true or false, it seems like it is something that will be addressed soon. bork
I am very skeptical about this find. Both the Tiktaalik and the paddlefish appear in the fossil record around the same time, between 300 and 400 mya. That is approximately 50 million years before dinosaurs. The paddlefish of the past looks almost identical to the one in the present, and tiktaalik is extinct. So, my question is: Where is the transitional? I'd love to see the similar hox genes expressed in the paddlefish , just to see what happens. Your thoughts? Mario A. Lopez
Sounds like the NREH (Non-Random Evolutionary Hypothesis by Dr.Lee Spetner) to me. Atom
Here's another wonderful quote: "Although this pattern of genes clearly helps to make hands and feet today in tetrapods, that may not be their original intent, Shubin said. "Here’s a fish that doesn’t have an autopod but is still using those genes in a second phase to help pattern out a fin that doesn’t have fingers, never did, and is very far removed from tetrapods." The capability of building limbs with fingers and toes existed for a long period of time, but it took a set of environmental triggers to make use of that capability. According to Shubin, in the Late Devonian, animals like Tiktaalik and its descendants acquired limbs with fingers using this primitive design, largely because their ecosystem—the small streams that they lived in—was new." So, the "tools" (Hox genes) were there, and it was just awaiting the right environment triggers. This sure doesn't sound like "random mutations" and Natural Selection. PaV

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