What a shoddy piece of work is man

It seems kind of cheap to win the ‘most commented’ slot on Nature News simply by writing an article about science and religion. You just know that will happen; there is nothing like it for provoking readers to offer their tuppence’ worth, and in particular for drawing reams of comment from the fundamentalist fringe. My latest Muse (pre-edited version below) is no exception. I am, however, entertained by the thoughtful remark of Bjørn Brembs, who says:

“As usual, your article is very reasoned, thoughtful and balanced. Reading some of the comments here, however, I fear you are making a common mistake, so accurately described by PZ Myers: "Where scientists are often handicapped is that they don't recognize the depth of the denial on the other side, and that their opponents really are happily butting their heads against the rock hard foundation of the science. We tend to assume the creationists can't really be that stupid, and figure they must have some legitimate complaint about some aspect of evolution with which we can sympathize. They don't. They really are that nuts."

Does it make sense to to try and reason thoughtfully with someone who prefers "magic man did it" over "I don't know" as an answer to scientific questions? Couldn't it be that this peculiar and revealing preference alone constitutes evidence enough that this person may not be amenable to reason at all?”

Bjørn is probably right in most cases, but I should say that I’d be a sad fool indeed if I wrote pieces like this under any belief that they would convert creationists. No, I do it because I think the issues are interesting, namely: how well has evolution done in designing our genome? (Not very.) To what extent does evolution optimize anything at all? (Not much.) And how come we work pretty well despite all this mess? (That’s the really big question.)

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Our genome won't win any design awards and doesn't speak well of the intelligence of its 'designer'.

Helena: They do say that man was created by God.

Domin: So much the worse for them.

This exchange in Karel Capek’s 1921 play R.U.R., which coined the word ‘robot’, is abundantly vindicated by our burgeoning understanding of human biology. Harry Domin, director general of the robot-making company R.U.R., jeers that ‘God had no idea about modern technology’, implying that the design of human-like bodies is now something we can do better ourselves.

Like most tales of making artificial people, R.U.R. contains a Faustian moral about hubris. But whether or not we could do better, it’s true that the human body is hardly a masterpiece of intelligent planning. Most famously, the eye’s retina is wired back to front so that the wiring has to pass back through the screen of light receptors, imposing a blind spot.

Now John Avise, an evolutionary geneticist at the University of California at Irvine, has catalogued the array of clumsy flaws and inefficiencies at the fundamental level of the genome. His paper , published in the Proceedings of the National Academy of Sciences USA [1], throws down the gauntlet to advocates of intelligent design, the pseudo-scientific face of religious creationism. What Intelligent Designer, Avise asks, would make such a botch?

Occasional botches are, meanwhile, precisely what we would expect from Darwinian evolution, which is blind to the big picture but merely tinkers short-sightedly to wring incremental adaptive advantage from the materials at hand. Just as in technology (and for analogous reasons), this produces ‘lock-in’ effects in which strategies that are sub-optimal from a global perspective persist because it is impractical to go back and improve them.

Intelligent design (ID) does not have to deny that evolution occurs, but it invokes an interventionist God who steps in to guide the process, constructing biological devices allegedly too ‘irreducibly complex’ to have been assembled by blind random mutation and natural selection, such as (ironically) the eye or the flagellar motor of bacteria [2].

As Avise points out, ID is problematic in purely theological terms. Were I inclined to believe in an omnipotent God, I should be far more impressed by one who had intuited that a world in which natural selection operates autonomously will lead to beings that function as well as humans (for all our flaws) than by one who was constantly having to step in and make adjustments. I’m not alone in that: Robert Boyle felt that it demeaned God to suppose he needed constantly to intervene in nature: ‘all things’, he said, ‘proceed, according to the artificer’s first design, and… do not require the peculiar interposing of the artificer, or any intelligent agent employed by him [3].

But ID must also confront the issue of theodicy: the evident fact that our world is imperfect. Human free will allegedly absolves God of responsibility for our ‘evil acts’ – but what about the innocent deaths caused by disease, natural disasters and so forth? Infelicities in the course of nature were already sufficiently evident in the eighteenth century for philosopher David Hume to imply that God might be considered a ‘stupid mechanic’. And in the early twentieth century, the physician Archibald Garrod pointed out how many human ailments are the result not of God’s wrath or the malice of demons but of ‘inborn errors’ in our biochemistry [4,5]

Many of these ‘errors’ can now be pinpointed to genetic mutations: at a recent count, there are around 75,000 disease-linked mutations [6]. But the ‘unintelligent design’ of our genomes, Avise says, goes well beyond such flaws, which might otherwise be dismissed as glitches in a mostly excellent contrivance.

The ubiquity of introns – sequences that must be expensively excised from transcribed genes before translation to proteins – seems to be a potentially harmful encumbrance. And numerous regulatory mechanisms are needed to patch up problems in gene activity, for example by silencing or destroying imperfectly transcribed mRNA (the templates for protein synthesis). Regulatory breakdowns may cause disease.

Why design a genome so poorly that it needs all this surveillance? Why are there so many wasteful repetitions of genes and gene-fragments, all of which have to be redundantly replicated in cell division? And why are we plagued by chromosome-hopping ‘mobile elements’ in our DNA that seem only to pose health risks?

These design flaws, Avise says, ‘extend the age-old theodicy challenge, traditionally motivated by obvious imperfections at the levels of human morphology and behavior, into the innermost molecular sanctum of our physical being.’

Avise wisely avers that this catalogue of errors should deter attempts to use religion to explain the minutiae of the natural world, and return it to its proper sphere as (one) source of counsel about how to live.

But his paper is equally valuable in demolishing the current secular tendency to reify and idealize nature through the notion that evolution is a non-teleological means of producing ‘perfect’ design. The Panglossian view that nature is refined by natural selection to some ‘optimal’ state exerts a dangerous tug in the field of biomimetics. But we should be surprised that some enzymes seem indeed to exhibit the maximum theoretical catalytic efficiency [7], rather than to imagine that this is nature’s default state. On the whole there are too many (dynamic) variables in evolutionary biology for ‘optimal’ to be a meaningful concept.

However – although heaven forbid that this should seem to let ID off the hook – it is worth pointing out that some of the genomic inefficiencies Avise lists are still imperfectly understood. We might be wise to hold back from writing them off as ‘flaws’, lest we make the same mistake evident in the labelling as ‘junk DNA’ genomic material that seems increasingly to play a biological role. There seems little prospect that the genome will ever emerge as a paragon of good engineering, but we shouldn’t too quickly derogate that which we do not yet understand.

References

1. Avise, J. C. Proc. Natl Acad. Sci. USA doi:10.1073/pnas.0914609107.

2. Behe, M. J. Darwin’s Black Box: The Biochemical Challenge to Evolution (Free Press, New York, 1996).

3. Boyle, R. ‘Free inquiry’, in The Works of the Honourable Robert Boyle Vol. 5, ed. T. Birch, p.163 (Georg Olms, Hildesheim, 1965-6).

4. Garrod, A. Inborn Errors of Metabolism (Oxford University Press, London, 1909).

5. Garrod, A. The Inborn Factors of Inherited Disease (Clarendon Press, Oxford, 1931).

6. Stenson, P. D. et al., Hum. Mutat. 21, 577581 (2003).

7. Albery, W. J. & Knowles, J. R. Biochemistry 15, 5631-5640 (1976).