but anyway, this is way off course, and you have still yet to either try to defend irreducible complexity, or concede it to be BS.
And let's not confuse the issue... "irreducible complexity" is a
political phrase used by the likes of Behe to further a religious argument against evolutionary theory. It is not a scientific concept.
Of course, with a little research and understanding, the whole idea of irreducible complexity is crap. Essentially Behe and his ilk are saying that some biological structures and systems exist in a complicated, multi-part state that cannot exist if a single component of it breaks down or is rendered inert.
Now, Behe is a biochemist rather than an evolutionary scientist or a geneticist so you might think that we could forgive him for being a little thick on the building blocks of life (after all, biochemists spend most of their lives memorizing and deciphering the components of complex biological systems and how they interact with each other rather than how they came to be and what their genetic ancestry is), but Behe is unforgiveable in the sense that he spent a good deal of time in his post-doc actually working on DNA itself for the NIH. Tsk tsk.
Biological enzymatic systems are derived from proteins, which exist of course because DNA tells the cell how to make them. DNA is not a perfect system by any stretch of the imagination (here's another flaw with ID, mind you) and thus protein synthesis is not only prone to mistakes, but DNA itself gets altered significantly over time due to mutation, some of which occur in more areas than others. Had the Behe crowd paid attention in their first-year undergraduate biology courses, they'd know that. However, it seems they like to jump right to what is than what it came from. *sigh*
No system is irreducibly complex - at least, not in its evolutionary lineage. They all started from a set of proteins that took on new and eventually lost their old functions due to mutation. As it happens, selection pressures can cause whole regions of DNA to change rapidly, thus affecting all the genes (and the proteins producing them) in concert. Early systems had several functions. Over time, they have specialized from many functions with interchangeable parts to fewer and fewer functions with highly specialized components. Once that specialization occurs, and systems become dependent on certain single-protein components, and entire system can be disrupted by the loss of one. It's not uncommon. But if we look at ancestral species, we find their systems are much more flexible though less efficient.
I have an example. The gene "hedgehog" is present in pretty much every living thing in kingdom Animalia. And it has dozens of purposes in many different species, though in every single one it is involvement in axis definition in the early embryo during development. In simple animals (sponges, nematodes, etc) hedgehog defines axes. In fish, hedghog defines axes and regulates parts of eye development. In humans we still haven't figured out every that hedgehod protein
s do, because the gene has been duplicated and mutated into several different forms, all with different jobs. In each case, the ancestry of the gene leads back to one single gene with the same sequence, but over time it has diverged and kept its original role while also becoming involved in other systems. The protein has taken on new roles in addition to its old one. Does that make a system with a hedgehog variant involved along with 30 other proteins "irreducibly complex" if its required for life? No... it means that the system has become so specialized that without components that have changed over time to fit a particular functional niche, it will not work today. It by no means says that it's therefore impossible for it to have evolved, because we can trace the evolutionary lineage of hedgehog proteins and see where and when they diverged.
The same is true of many other proteins. Honeybees use a protein called "major royal jelly protein" to stimulate the production of queens. Turns out those genes are actually derivatives of another genetic system, "yellow" which is present in fruit flies and regulates abdomen colouration.
Irreducible complexity is a classic example of trying to pick at evolutionary theory by picking apart the details, but unfortunately for Behe and his brethren other people DO understand the details and can scientifically and factually demonstrate them... which leaves him and his ID crowd, as usual, standing in the corner shouting blithering nonsense with egg on their faces.
I've long since quit actually reading the nonsense that he spews in public because it has no scientific merit whatsoever.
That, and I have a burning hatred for biochemistry.
