In re: photovoltaics: as far as I can see, this idea was probably rejected very early in the design process, because it doesn’t meet a fundamental design requirement: flexibility. Obviously, leaves (and skin) would be more difficult to engineer with a rigid, yet fragile surface. Photo cells are just like most any other man-made design, which, as noted above, are known for their inability to adapt to changing pressures of any kind. The increase in efficiency is the result of a greatly simplified, and hence less-robust, architecture.

Agreed about never regarding ignorance, even expert ignorance, of how to do it as proof that it is impossible.

“Those ‘scientists’ say your uncle was an EAR OF SUPER CORN! Hahaha! Are you gonna believe that?! Tell me then: why is there still super corn?!”

Yes, in theory, but the kicker is that you’d still need some way of carrying fluid streams (with nutrients, waste and operational gubbins) across the joint. Otherwise the structure at the far end will die and rot in short order. A few hose-like structures would do it at a bare minimum. (Think blood vessels or xylem/phloem.) But those’ll get irretrievably tangled as the wheel rotates, so it’s not an option.

I reckon you could probably manage it with dead wheels, particularly if you could find some way of replacing them as they rotted. There’s a quadruped species in a Phillip Pullman novel (mulefa) that do something like this with a symbiotic plant, which is far-fetched but not, to my mind, biologically implausible in the way that living wheels seem to be. I stress ‘seem’ – I’m very wary of saying things are implausible – still less impossible – biologically.

This is a key point to bear in mind, whether you’re talking evolution or elsewhere. “I’ve never heard a good model of how it could possibly work” is very far from rock-solid proof that it it can’t, even with an added, “despite having spent happy hours with biochemists and biologists musing about how you could do it.” But it is jolly unlikely.

[Of course the obvious option – which you do find all over the place – is to turn the entire organism in to a single wheel. There are plenty of small, round organisms, and many larger organisms can form themselves in to a roundish shape and roll if the need arises.]

Can’t a ball and socket achieve this? My skeleton is full of them. Works better with lube, but biological systems make much use of that as well.

Absolutely, if the examiners are aware of restriction endonucleases (bacterial enzymes that cut specific, usually palindromic, 6-base sequences in bacterial viruses) and are capable of DNA sequencing. Most of the vectors we use have a region called the “polylinker,” usually synthetic, that is chock-full of these restriction endonuclase sites, for insertion of the DNA to be expressed.

Rereading your comment, I see that my first take oversimplified your position somewhat. It’s true that a different sort of intelligence may design differently. It is also true that Darwinian evolution would find different solutions given an entirely different environment, e.g., a different planet. It may be that on another planet, photovoltaics are a solution Darwinism would find. But it may not. Since we have no real data about speculative alternative types of advanced minds or speculative extraterrestrial evolution, we can only speak of such things to the extent that we have theoretical models of how they would work, and can only speak of how we could or could not distinguish the artifacts if we have models of how to make such distinctions. So we’re back to building models based on the evolution and the minds that we have.

I think brittleness has a lot to do with it. Also, streamlining, which is related. Things that really were created for a certain purpose tend to have all elements clearly directed towards that end (though the human propensity for decoration is problematic here, and may reflect an emulation of nature with its seemingly bottomless complexity and elements of no apparent functionality).

Bakho points out that corn (maize for our foreign guests) is incapable of reproducing on its own. Several other crops are in similar situations. The varieties of bananas that we eat need human cultivation to spread (they lack seeds to begin with). I don’t expect any evidence of human tinkering with genetics to survive the first century after humans go poof, let alone survive to irritate future intelligent species.

Are you under the impression that anything you said contradicts what I said? If not, and assuming you are, as it appears, responding to me, I don’t see the purpose of your comment. If so, you are about three steps behind the argument. Of course, evolution tinkers and moves incrementally without internally-determined endpoints. That is so basic a premise of what I am saying that I did not think it needed to be stated explicitly. However, human minds also design things, using processes such as working towards explicit goals, deploying abstract models, and evaluating counterfactuals without actualizing them that are not available to biological evolution. Hence, the two processes are different, and I’m inquiring as to whether a) the differences can be determined from the artifacts, which is pretty much the main topic of this post and b) what useful things we may be able to tell from looking at what sort of problems each approach solves well.

Keith,

Whether the argument helps or hinders ID is an instrumental question and not really a legitimate consideration in evaluating scientific arguments. Nonetheless, if any possible type of design is consistent with either the Darwinian model or intentional design, then the evolutionist claim to establish Darwinism on the basis of the observed structure of the natural world is considerably weakened and very vulnerable to charges of unfalsifiability. Since we know from our own activity as humans that intelligent design exists, to establish that the structure of the natural world has another basis, one has to claim to be able to distinguish products of Darwinian processes from products of intentional design. As it happens, I do think such distinction is possible. Evolution does not give us cars, yet it is obviously possible for cars to exist. Yet humans have not invented an eye, even given a pre-existing model.

Consider what is probably the most basic problem of life: harvesting energy from the sun. Darwinism gave us photosynthesis. Billions of years of evolution with horizontal gene transfer, asexual reproduction, sexual reproduction, changes of stress from rapid environmental change, etc., have not significantly improved on this. The human mind invented photovoltaics, which were, I believe, even in the first generation more powerful than photosynthesis. If one looks at evolution as a computation process exploring a solution space – the premise of artificial life and such things – and looks at the mind similarly as a computational process, the computational resources given to this problem by evolution are vastly greater those given by the human mind, yet the mind, actually just a few people, though obviously drawing on previously-established cultural knowledge, vastly improved on the Darwinian solution. In fact, I see no basis for supposing that photovoltaics were a solution that Darwinism ever would have found; it doesn’t seem to have been approaching them. Because there is no incremental path? Perhaps, or perhaps because of other limitations of Darwinian processes. Freeman Dyson, in a recent NYRB, regards it as a mystery that evolution in no climate produced plants with black leaves to absorb sunlight more efficiently than green (a more modest, but also easier, enhancement than photovoltaics). But maybe there is no reason to assume that evolution will always find the best solution, or even as good a solution as the mind can devise; it often does, but its approach seems to us incomprehensively brilliant in some ways and stupid in others, which to me supports the notion that evolution traverses the solution space much differently than we do.

abb1, yes, I’m familiar with that. I liked David Sloan Wilson’s Darwin’s Cathedral, which is an argument along those lines.

In my opinion, the “incremental path” argument against evolved wheels is flawed and inadvertently provides ammunition to ID proponents. Basically, I think the flaw is in thinking that we can reliably tell when something could not come about via an incremental path. After all, that error is essentially the entire opposition to evolution.

I’ve always thought that the real problem of an evolved wheel is that it’s such a weird structure, from a biological viewpoint. The wheel has to turn independently of its axis, which would be very complicated to achieve for living tissue. Alternatively, a wheel could be formed and then the living tissue could retreat to the axis. But then you’d have to ask exactly what kind of selective pressure could exist that would prefer this structure over others?

It’s not so much that there’s no incremental process that could allow the evolution of the wheel, it’s that it’s just so unlikely relative to others that would achieve roughly the same result. We humans are confounded by this example because we see the simplicity of the wheel and erroneously think that it is a simple solution to a simple problem in evolutionary terms. But it’s probably not.

And thus here I find I disagree with those who are saying that there’s really no way to detect the difference between designed and evolved structures. I agree that there’s probably not any strong qualitative distinction between the two (in terms of the structures, of course). But there’s a whole bunch of quantitative differences you can easily see. Designed structures have little general redundancy and they are usually “brittle”. That is, they easily fail completely outside of their intended environment. The key in that last sentence is to realize just how narrow “intended environment” is for designed objects as compared to biological structures. It may seem that an ecological niche is “narrow”, but not in the same sense as the “niche” in which an airplane operates, for example.

Arguably, however, these distinctions rely upon how an intelligent creature prefers to design! One can imagine a much more biologically-oriented worldview that both prefers explicit designs that mimic evolved biological structures, and/or prefers to use evolutionary processes for design purposes. In those cases, it would obviously be much harder to differentiate design from intelligence-independent evolution.

All of which argues that this notion of “design” versus “evolved” may be a bit of a red herring, distracting us from the qualitative distinctions that are more descriptive, as science should be. Creationism and ID really are regressive science because they explicitly embrace teleology. It’s not so much that teleology is essentially unscientific, as it is the case that teleology is so often unhelpful or misleading for scientific purposes. Just so with creationism and ID.