The history of the qwerty keyboard - almost certainly the one you are using to access this article, and the one I'm using to write it with - is great example of a design which becomes fixed for reasons which have nothing to do with why it is the way it is in the first place. But you will never be able to work out why that keyboard has its basic layout by examining your computer or smart phone, no matter how detailed your examination is or how completely you understand it.
Understanding why this is so helps understand how groups of species, whether families, phyla, orders, or kingdoms - whatever level - get saddled with certain unchangeable basic body plans. The history of the typewriter can he read in this Wikipedia article and of the qwerty keyboard in this one.
Briefly, typewriters were designed for producing a small number of written copies quickly, unlike printing which used type to produce a large number of copies and which needed the type to be set in blocks ready to go into a printing press. You might think that there would be some obvious logic in the way the keys are arranged on the keyboard and yet this appears to be almost random. However, there is, or rather was a logic, though not an obvious one.
Typewriters work by moving the paper past a fixed position where the metal type, mounted on a hammer, and operated by levers fixed to keys, can strike an inked ribbon, which also moves past the print position. The problem is that each piece of typeface has to move into position, hit the ribbon with enough force to transfer the ink to the paper, and clear the way for the next piece of typeface. Typing at 60 words a minute, with an average of five characters per word, a typewriter must cope with five hits per second. This creates a potential for jamming which increases as the typing speed of the user increases and especially if the user happens to hit two keys together.
One solution would have been to lock the other keys as soon as one was pressed but, apart from the hugely complicated engineering this would have needed, it would have slowed typing down to such an extent that any advantage in using a type-writer in the first place would have been mostly lost.
In the early days of course, there was complete freedom to experiment with different layouts because few, if any people actually used it regularly. Other designs included ones with the vowels and the 'y' arranged on a top row. By a process of trial and error, and possibly based on a study of the frequency of letter pairs in English, Sholes changed the keyboard layout many times to arrive eventually at something close to the qwerty layout, at which point it was sold to E.Remington & Son. Their engineers made a few more adjustments to arrive at more or less the present layout.
One interesting vestige of the original alphabetic layout is the sequence in the centre row of the letter keys - DFGHJKL - which, with just the vowels missing, is a section of the standard Latin alphabet, giving a fossil-like clue about the original layout.
|Typing Pool, 1956|
Courses were organised and certificates of proficiency issued, and asked for by employers. Fast, accurate typing speeds were at a premium, though, because they were normally acquired by women, they never commanded high wages. And suddenly there were job opportunities for women in secretarial work which, until then, had been a male occupation. But that's a different story...
Other manufacturers soon came into the typewriter market, selling typewriters, not with new, more efficient keyboard layouts, (or if they tried they failed) but ones which people with pre-existing skills could use. No boss in his right mind was going to buy his secretaries typewriters they couldn't use and which they were going to have to learn afresh. Competition was all concerned with price, portability, durability, type-face, etc, but one thing which no manufacturer could seriously risk tampering with was the basic keyboard layout. Additional keys like fractions, currency symbols, etc, could be added, but not the basic qwerty arrangement.
The evolution of the keyboard had reached the point at which the cost of changing the layout would outweigh any benefits. The qwerty keyboard had become effectively fixed in our culture and each new generation was taught to use it, but no other.
Even with the migration to electric typewriters, where daisy-wheel and golf-ball heads made jamming a thing of the past, the layout could not be changed, not for any technical reasons but because it would have meant an unacceptable, even if temporary, loss of efficiency.
And so we have arrived at computers, in many ways the descendants of typewriters, with a keyboard originally designed to avoid the typeface hammers jamming - something no observer could have worked out in the absence of any knowledge of the history of the typewriter. There is no trace left of the movable carriage, the ink ribbon, the typeface, the operating levers, or even the paper and yet the layout of the qwerty keyboard can only be explained in terms of the engineering problems those things caused and how they were overcome, not optimally, but sufficiently.
The qwerty keyboard is even used in Japan where, not only does the letter layout bear no relationship to letter frequency or sequence in any Japanese alphabet, but the letters are not even a normal part of the Japanese written scripts. Instead, software is needed to transliterate combinations of keystrokes into Kanji, Hiragana and Katakana characters. How on earth could the proverbial spaceman observing a Japanese secretary at work, work out why he/she is using that keyboard with that layout? The clues are nowhere to be found either inside or outside the computer he/she is using.
But, from our knowledge of the origins - of the evolution - of the qwerty keyboard, the increased efficiency it gave us in our ability to communicate, and how this came to be fixed in our culture, the layout is perfectly understandable, as is the difficulty with changing it.
|Turtle surfacing to breathe|
Once a feature gives a significant advantage and allows a species to evolve in a new direction, it quickly becomes fixed and forces the species in that direction with no option to go into reverse. To all intents and purposes, it is impossible for a species to de-evolve because the short-term loss of efficiency (in this case survivability) far outweighs the potential long-term gain. Serious loss of efficiency almost guarantees instant removal from the gene-pool. It's the equivalent of a keyboard manufacturer coming up with a brilliant new layout and hawking it around today's offices and IT departments. He would simply be told "we use qwerty keyboards, thanks."
The major divisions into kingdoms, phyla, classes, orders, etc, all reflect major and irreversible directions taken by evolution in ways almost exactly analogous to the way our culture evolved with the qwerty keyboard, and, as with the qwerty keyboard used on Japanese computers, it becomes impossible to reverse engineer the layout from first principles. Unless the evolutionary history is known from other sources and the conditions in which it evolved are understood it may be impossible to work out how a taxon arrived at its current 'design'. Even little clues like the vestigial DFGHJKL sequence can only give a hint of the origins and to someone who only knew Japanese, that might not even register as a clue.
And this of course is where the 'intelligent design' proponents (aka creationists) come in. They will look at structures analogous to the qwerty keyboard on your laptop and tell you that there is no logical way this 'irreducibly complex' layout could have evolved because there is no movable carriage, no levers or inked ribbon, no metal typeface mounted on hammers operated by levers and no logical way the layout could have evolved from a precursor because there is no precursor to be found.
But then, we know differently, don't we. We know that evolution will often cover it's tracks because it feels no obligation to record every little step or to preserve redundant structures and only occasionally leaves us fossils like the DFGHJKL sequence, although the history of the genome as recorded in DNA, often has a fairly good record still because the genome is where the real change has occurred.
When arranged in order of degrees of difference the resulting 'tree' reconstructs the evolution of species, families, orders, classes, phyla and kingdoms, and then almost all of biology suddenly makes sense in terms of decent with modification from a common ancestor which lived a very long time ago, just as the layout of the qwerty computer keyboard makes sense when we know the history, and no sense at all when looked at as the work of an intelligent designer.
Now, I know the creationists who have read this far, and I suspect there will be few, will now be jumping up and down excitedly and claiming I've 'proved' intelligent design because the qwerty keyboard had to be intelligently designed in the first place. But the point is not how it got to be in it's present form but how, now it has become fixed in our culture, it is almost impossible to change it, and how, because it is impossible to change it, we still have it despite the fact that we have moved way beyond the technology which needed that layout in the first place and for which no evidence is to be found in the keyboard or computer it's attached to. This move moreover was facilitated by the existence of the typewriter and typing skills in the first place. It is an example of the 'scaffold' method of construction where the scaffolding itself becomes redundant, just as happened with your 'irreducibly complex designs'.
Besides, the trial and error method Sholes used, measuring each variation against a standard for fitness (i.e. less jams and faster speed) and then building on that for the next 'generation' is a basic evolutionary algorithm. Given time, variation, replication and selection, nature will inevitably simulate this process, using only the test of fitness to survive.