A Primer on the Tree of Life--Part 4 (Darwin's "tree of life" comes crashing down...as predicted)

Discovery Institute ^ | May 11, 2009 | Casey Luskin

[GodGunsGuts]

A Primer on the Tree of Life (Part 4)

Note: This is Part 4 in a 5-part series titled "A Primer on the Tree of Life." Read Part 1 here, Part 2 here, and Part 3 here.

Homology in Crisis
As Mayr suggests, there are other examples where genetic similarity appears in unexpected places. Biologically functional similarity that is thought to be the result of inheritance from a common ancestor is called “homology.”

The concept of “homology” has been thrown into a crisis via observations, like those of Mayr, that the same genes control the growth of non-homologous body parts. Pax-6 is just one example. Another is the fact that the same gene controls the development of limbs in widely diverse types organisms that have wholly different types of limbs. The methodology used to infer homology was also challenged when it was discovered that different developmental pathways control the growth of body parts otherwise thought to be homologous. As the textbook Explore Evolution observes:

In sharks, for example, the gut develops from cells in the roof of the embryonic cavity. In lampreys, the gut develops from cells on the floor of the cavity. And in frogs, the gut develops from cells from both the roof and the floor of the embryonic cavity. This discovery—that homologous structures can be produced by different developmental pathways—contradicts what we would expect to find if all vertebrates share a common ancestor. … To summarize, biologists have made two discoveries that challenge the argument from anatomical homology. The first is that the development of homologous structures can be governed by different genes and can follow different developmental pathways. The second discovery, conversely, is that sometimes the same gene plays a role in producing different adult structures. Both of these discoveries seem to contradict neo-Darwinian expectations.¹⁵

Perhaps this evidence is just the result of “hidden potentials of the genotype,” or perhaps it contradicts neo-Darwinian expectations because neo-Darwinism is wrong.

Reference Cited:
[15.] Stephen C. Meyer, Scott Minnich, Jonathan Moneymaker, Paul A. Nelson, and Ralph Seelke, Explore Evolution: The Arguments For and Against Neo-Darwinism, pgs. 44-45 (Hill House, 2007).”

Posted by Casey Luskin on May 11, 2009 7:46

[GodGunsGuts]

Be sure to read entire series...excellent!!!

[Ha Ha Thats Very Logical]

This discovery—that homologous structures can be produced by different developmental pathways—contradicts what we would expect to find if all vertebrates share a common ancestor.

Well that's wrong right there. People have talked about convergent evolution for a long time--the most common example is how birds' wings and bats' wings aren't constructed the same way.

Have you yet found the place a creationist "predicted" the end of the tree of life? Have you yet figured out that the reasons it's being challenged actually make it less compatible with creationism, not more?

[FormerRep]

Your quoted passage is meaningless. The differentiation of basal cells into specialized cells does not require that they be sourced from the same loci during the envagination process. Why not look up some basic embryology like the work done by my friends at Vanderbilt.

Those articles are again cherry picking what they hope would cast doubt without ever looking at the merits of their own arguments. This is why the creation science websites and it’s articles are so summarilly dismissed.

[GodGunsGuts]

That goes all the way back to the Bible that every biblical creation scientist believes is God’s historical account of creation. If you read Genesis, you will see that God tells us that each living kind was created fully formed and fully functional. This is why creation scientists have long predicted that Darwin’s single branching tree would come crashing down. And you are quite mistaken, the very same data that challenges Darwin’s ToL is actually quite supportive of the creationist ‘forest’ or ‘orchard of life.’

[GodGunsGuts]

Of course it does not require it. The point is that it is the opposite of what neo-Darwinism expected re: the argument from anatomical homology.

PS You should read the whole series...it is excellent (not to mention devastating).

[<1/1,000,000th%]

Earth sciences and law.

Interestng combination.

[count-your-change]

The “convergent evolution” is a Darwinist deus ex machina,
to explain how the different operations of bird's and bat's wings accomplish the same task, flying.

Rather like a wood chipper and a termite show “convergent evolution” because each “chews” wood.

[Ha Ha Thats Very Logical]

the very same data that challenges Darwin’s ToL is actually quite supportive of the creationist ‘forest’ or ‘orchard of life.’

Care to walk us through that? The articles you've been posting on the subject have been about how the problem with the Tree is that the branches don't seem to be that distinct anymore--in other words, that it's harder than ever to say what a "kind" is.

[Ha Ha Thats Very Logical]

Rather like a wood chipper and a termite show “convergent evolution” because each “chews” wood.

Not like that at all. There's so much wrong with that analogy, I wouldn't know where to start correcting it.

No, I take that back. I'd start by pointing out that wood chippers don't reproduce, so they don't undergo evolution, convergent or otherwise (except metaphorically).

[count-your-change]

And birds and bats and termites ALL have a common ancestor?

If one accepts that premise then any creature that flies should be included in the “convergent evolution” group.

Butterflies, dragonflies, gnats, et al. Each uses the resistance of air to movement to fly so that some similarities of design would be expected to exist just like the jaws of a termite cut wood while the blades of a chipper cut wood.

The analogy is just as good as “convergent evolution”.