Evolution by natural selection explains how life can adapt and be gradually modified by the trial and error process of natural selection. If you don’t know how this process works, watch this first. Or read any of my various evolution blogs here. Though try to steer clear of the “RE: whatever” blogs, as they are me arguing with creationists, and will be far less informative.
But if you do know the basics, then read on.
Anyhow, evolution explains how species adapt to their environment but also is a mechanism that can give rise to complex biological mechanisms. A guy named Micheal Behe, one of the few real, credentialed scientists in the anti-evolution movement, wrote a book called Darwin’s Black Box: The Biochemical Challenge to Evolution, designed not for scientists, but for a lay, religious audience. The book claimed (without evidence or any experimentation whatsoever) that complex, inter-dependent systems could not evolve by slow, gradual modification of precursor mechanisms because they could not be simplified without completely breaking down. This is just a scientific sounding version of the watchmaker argument in theology. A watch needs many gears to function, take any gear away and it stops working, therefore a creator must have put them all together so they could work. So too the supposedly secular “Intelligent Design” movement (which is tooootally different from the religious creationism movement, aside from using slightly modified versions of the same textbooks and being spearheaded by the exact same group of conservative christians and evangelists) insists that complex biological systems with inter-dependent parts indicate that someone (they’re not saying who ::wink wink::) must’ve put all the different bits together so it could work.
There is however a problem with this. A plant or a germ or a dog are not actually like a watch or anything man-made. When an architect builds a building he can create the frame first, put up scaffolding etc, planning for the next phase. But evolution cannot plan ahead. It must do only what can be accomplished by means of slow, gradual modifications of what came before.
So to use language as an analogy, evolution works this way:
Slight, gradual changes, each one fully functional. Or in this analogy the parallel to functionality is simply being a real word.
And this is what we find in biochemestry as well. Micheal Behe’s central example of “irreducible complexity” is the bacteria flagellum.
For those of you who don’t know, it is a sort of out board motor for many germs, it’s a whip-like structure that spins and propels germs and other cells through the microscopic world. It’s complex, made of dozens of parts:
Turns out we can take virtually all of it’s parts away and it remains functional, though it’s function changes or diminishes at each stage. Here are just the major intermediates, all of which are fully functional, and most or all of which exist in other cells or other parts of the cell:
In fact most of the examples of “irreducibly complex” mechanisms in his book were known at the time to be reducibly complex, and he didn’t see fit to mention it.
But you go to any creationist or “intelligent design” website and they are still using these fraudulent arguments years later. There are frauds in science to be sure, but they are denounced as frauds, not embraced and upheld and fought for. Because a scientist’s priority is finding the truth, whatever it may be – not proclaiming The Truth.
But here’s where it gets even more interesting (and lame, for the ID side). Evolution can and has been shown to produce irreducibly complex mechanisms. That’s right, irreducible complexity, the one and only biological argument against evolution coming from an actual biologist, is a common product of evolution! Haha.
For instance, going back to our language analogy:
Sod is irreducibly complex. It cannot be broken down to any of it’s precursors by removing parts.
Slight, gradual modifications, each one functional, but they modify the precursors so that it cannot be broken down, and is thus “irreducibly complex”. In this way it is often very hard to re-trace exactly how something has evolved, especially when we’re talking about cells which do not fossilize and leave no record or history for us to glean insights from. It would be like trying to track the history of a civilization that left no records or artifacts based on it’s current state. Very hard indeed, no? But in the case of intelligent design that really doesn’t matter though because the above has more than destroyed the challenge to evolution, showing irreducible complexity, even where it does exist (as it surely does somewhere, though the creationists can’t even find genuine examples of it) is irrelevant as evolution can easily produce it.
So yeah, when someone says x thing is “irreducibly complex” in a creationist argument or blog, give them the link to this blog.