Darwin Wins One
by MikeGeneOn Telic Thoughts, we like to focus on aspects of life and evolution that help us see evolution as something that may be more interesting than conventional neo-Darwinian explanations would have us expect. But it looks like good old-fashioned, Darwinian gradualism may have played the crucial role in whale evolution:
the gradual shrinkage of the whales' hind limbs over 15 million years was the result of slowly accumulated genetic changes that influenced the size of the limbs and that these changes happened sometime late in development, during the fetal period.
Relying on anatomical data, the researchers argue that Sonic hedgehog (a crucial gene in limb development) was inactivated late in whale evolution.
On the other hand, another report on the same study tells us that taking Sonic hedgehog offline early on seems to have been the key event in dolphin evolution. 
May 23rd, 2006 at 12:03 pm
MikeGene,
Does this prove anything except that Neo-Darwinism will adapt to any research finding?
Gradualism - "just what we expected".
Rapid gene inactivation - "just what we expected".
We really need a new paradigm or we will just end up with Neo-Neo-Neo-Darwinism.
Comment by chunkdz — May 23, 2006 @ 12:03 pm
May 23rd, 2006 at 1:18 pm
Does this prove anything except that Neo-Darwinism will adapt to any research finding?
Not in this case. It was already known that we could get large morphological changes from either a large number of accumulated small changes, or from a small number of mutations to certain key genes. So both observations were already consistent with the theory.
Now, there are some observations that would have been inconsistent with the theory…for example, if the dolphin homeobox genes were more fish-like than mammal-like.
If that had happened, then, yes, neo-Darwinism would be modified to take the new information into account. We might even wind up deciding that dolphins had been genetically engineered somehow, and add in some useful bits of Intelligent Design theory. (Of course we wouldn't throw out neo-Darwinism completely, because we already know it works in some situations.)
We really need a new paradigm or we will just end up with Neo-Neo-Neo-Darwinism.
We don't have to add another "Neo-" every time we make a slight adjustment to a theory. If there's a paradigm shift, we'll probably just call the new theory "Modern Biology" to distinguish it from "Classical Biology".
Comment by chaosengineer — May 23, 2006 @ 1:18 pm
May 23rd, 2006 at 1:25 pm
Mike, certainly interesting research, and research that I believe, in fairness, should be viewed as consistent with the idea that the whale may have developed from an earlier limbed mammal. However, it is not clear what kind of win this is for traditional evolutionary theory. What we have, if I am reading the article correctly, is the loss/degradation of form/function over time. While interesting (just like the blind mole or the fused beetle wings), this seems to be rather irrelevant to the origin of the function in the first place. Evolution is supposed to be the creative engine behind the origin of genetic information, new body types and new functions, not just an observation of biological entropy. We know that complex systems can degrade over time, but whence all the biological innovation in the first place?
Perhaps there is another way to view the data that that might be more supportive of traditional evolutionary theory?
Comment by Eric Anderson — May 23, 2006 @ 1:25 pm
May 23rd, 2006 at 2:39 pm
It was already known that we could get large morphological changes from either a large number of accumulated small changes, or from a small number of mutations to certain key genes. So both observations were already consistent with the theory."”chaosengineer
Fisher's Microscope and Haldane's Ellipse
D. Waxman* and J. J. Welch"
vol. 166, no. 4 the american naturalist october 2005
http://www.lifesci.sussex.ac.u...
"The classic arguments in favor of micromutationalism"”
the doctrine that mutations of very small phenotypic effect
are the most likely to contribute to adaptation"”are given
by Fisher (1930). To support this position, Fisher offered
an analogy, comparing the effect of a mutation to the
"mechanical adaptation of an instrument, such as a microscope."
He claimed that "it is sufficiently obvious that
any large derangement will have a very small probability
of improving the adjustment," while in the case of the
smallest possible alterations, "the chance of improvement
should be almost exactly half" (Fisher 1930, pp. 37"“38).
In addition to his verbal analogy, Fisher introduced a
mathematical model of natural selection acting on multiple
quantitative traits."
Notice that Fisher's "verbal analogy" is a "design argument." It's the old "spanner in the works" argument, which creationists raised to the theory of natural selection. (For Americans a spanner is a wrench. The idea is that throwing a wrench into any finely-tuned mechanism is not likely to improve its performance.) Obviously, Fisher (like Darwin before him) was not peremptorily dismissive of "creationists" arguments. (Neo-Darwinists can turn a good old-fashioned "creationist" argument to advantage. But did the turn turn out to be a theoretical "advantage")
Especially interesting to me is Fisher's argument that as the coefficient of selection ->0 the probability that any mutation is beneficial ->1/2! The fallacy of Fisher's argument for "micromutationalism" is that there was no a priori reason to believe that life forms operate according to the same principles that human designs, mechanisms, do. Unless one, like Fisher (and Darwin) apparently, assumes a priori that those "design principles" are somehow informative about biological evolution. Which both Fisher and Darwin did assume. A plain falsification of "theory," both "evolutionary" and "design"! (I'm esp interested where exactly neither gets it quite right.)
It's true that Neo-Darwinian theorists understood that the principle of "strong causality" (as it is called in evolutionary computation) does not strictly apply. They knew that the magnitudes of causes do not match (with some probability) the magnitudes of effects. Typical of a complicated controlled process. But they did not really include that known fact in their theory"”for the obvious reason that it complicates the analysis of evolution (and design).
The whole history of the subject of "gradualism" is interesting.
Natura no facit saltum. (?)
Comment by Rock — May 23, 2006 @ 2:39 pm
May 23rd, 2006 at 2:48 pm
A plain falsification of "theory," both "evolutionary" and "design"!
I should say that Fisher's (Darwin's) and many people even today, make "naive" design arguments. I'm going to say "naive" rather than my usual mantra that these are "arguments from the ignorance of design."
Does it sound more friendly to say "naive" rather than "ignorant"
Comment by Rock — May 23, 2006 @ 2:48 pm
May 23rd, 2006 at 6:37 pm
chaosengineer wrote
Actually, such a find would not be deemed inconsistent. ND is remarkably nonplussed when genetic homology turns up in some unexpected places.
But hox expression is awfully different from gradual successive micromutations, yet both are proposed as mechanisms for creating novel morphology. ND being observational, rather than predictive, it can only take note of the loss of information. It makes no prediction about the generation of information.
The gap between large morphological changes and novel morphological changes is what ND's problem is.
Sorry, I wasn't serious. I was being facetious in order to make a point. That point is that ND has become a frankenstein made of the data that research has wrought. Some fits the theory, some doesn't. It doesn't seem to matter.
Comment by chunkdz — May 23, 2006 @ 6:37 pm
May 25th, 2006 at 7:49 pm
Actually, although Fisher illustrated his argument by reference to a well-understood familiar item that happens to be designed, it is fundamentally a mathematical argument rather than a design argument. Indeed, Fisher's reasoning should be familiar to anybody who has studied calculus. Basically, Fisher is pointing out that given a mathematical function y that is dependent upon some parameter x, then at a sufficiently high magnification the relationship between x and y can be accurately approximated over a small region by a straight line. Assuming that line has a nonzero slope (i.e. we are not already at a local optimum), then a small change in one direction will increase y, while a small change in the other direction will decrease y (hence the probability 1/2).
There is a problem with Fisher's argument, however, in that it assumes that arbitrarily small changes in x can be made. But we now know that genes are digital, not analog. Stuart Kauffman has pointed out that this introduces limitations in the complexity of the interdependencies among its parts that an organism can have and still be capable of evolving. In other words, the relationship between x and y cannot be so jagged that Fisher's assumption does not hold (i.e. the smallest possible genetic changes must usually produce small changes in fitness).
Comment by trrll — May 25, 2006 @ 7:49 pm
May 26th, 2006 at 4:18 pm
I have a question: If evolution is Mendelian then what's the point of Darwin? Who needs him?
Really, I'm asking, what really is the point of Darwin?
Who needs him?
Comment by Rock — May 26, 2006 @ 4:18 pm
May 27th, 2006 at 9:55 am
Darwin gave us natural selection as the mechanistic creative designer.
Comment by Mung — May 27, 2006 @ 9:55 am
May 27th, 2006 at 10:31 am
MECHA - ORGA ???
Emile Durkheim - Mechanical and Organic Solidarity?
Alfred North Whitehead - Mechanic and Organic Philosophy
R.O.C.K. - "the Watcher, the Stranger, the Witness, the Critic…the God-shaken, in whom the truth is inborn." - T.S. Eliot (1934)
Did Thomas Stearnes purposely forget 'the Designer'?
Darwin created, Darwin designed, Darwin constructed, Darwin travelled, Darwin experimented. Darwin is now on the 10 Pound note (which is a much stronger currency than the greenback, on which the line is written "In God We Trust," Psalm 56: 4)! Darwin left the Church of England for the church of Naturalism.
Whom does Rock, the ID critic/stranger trust IN? Or is there no other designer on earth than an ENGIneer? (Reminds me of the Rascals and Cyrill Sneer!) Darwin's turn of faith ending him up in Down was rather queer? So far inside Darwin's pants they became his tailor!
Darwin is unecessary in the discipline I'm engaged in, Rock, yet the majority of my fellow scholar-passengers seem to think otherwise. The hierarchy of sciences (applied, practical or theoretical) appears to underestimate your contribution to knowledge as much as it does to mine. Anthropology calls and the biologists will someday bow to the interdisciplinarity of the contemporary academy. But not now.
Comment by g arago — May 27, 2006 @ 10:31 am