The Epicurean Escape Hatch -- Richard Dawkins Responds to Stephen Meyer
In a comment at Why Evolution Is True, Richard Dawkins has deigned to descend from the atheist Mt. Olympus to comment on the Meyer et al. debate, and immediately stepped in a steaming pile of...organic matter. He was unimpressed by Steve Meyer's case:
Meyer was terrible, not because of his migraine but because of the content of his speech, which was written down BEFORE his migraine. When will these people understand that calculating how many gazillions of ways you can permute things at random is irrelevant. It's irrelevant, as Lawrence said, because natural selection is a NONRANDOM process. You'd think they'd realise that if it were THAT easy to disprove evolution no scientist would take evolution seriously. Do they really think we are so very stupid? Or are they cynically playing to the gallery, dazzling the naive audience with big numbers like 10^77, while knowing full well they are irrelevant?
Two issues here. The first concerns what Dawkins himself has argued about the role of natural selection at the origin of life, and the second concerns what selection can accomplish after life is up and running. In both cases, the "nonrandomness" of natural selection is entirely irrelevant. The small probabilities won't go away just because one waves natural selection at them.
1. And Dawkins knows this. He wrote about the problem, in fact, at length.
Indeed, the Richard Dawkins who wrote The Blind Watchmaker devoted an entire chapter, "Origins and Miracles," to the daunting probabilities entailed by an undirected search of sequence space. Moreover, Dawkins explained that natural selection couldn't solve the problem:
But cumulative selection cannot work unless there is some minimal machinery of replication and replicator power, and the only machinery of replication that we know seems too complicated to have come into existence by means of anything less than many generations of cumulative selection! Some people see this as a fundamental flaw in the whole theory of the blind watchmaker. (1987, pp. 199-200)
So what is Dawkins's solution to the unsolved problem of finding the functional sequences?
Luck. Seriously -- it's dumb luck. Make the universe a big enough place, with enough planets where life might have arisen -- never mind the biochemical details, which remain unknown -- and the small probabilities go away. You can win any lottery if you buy enough tickets.
Dawkins isn't the only evolutionist appealing to luck. More recently, Eugene Koonin calculated the probability of the undirected origin of the replication-translation system, using an RNA World scenario. Koonin concluded that "even in this toy model that assumes a deliberately inflated rate of RNA production, the probability that a coupled translation-replication emerges by chance...is P < 10^-1018."
No problem, says Koonin. The universe is a really big place, and wildly improbable things can happen in really big places:
The MWO [many worlds in one] version of the cosmological model of eternal inflation could suggest a way out of this conundrum because, in an infinite multiverse with a finite number of distinct macroscopic histories (each repeated an infinite number of times), emergence of even highly complex systems by chance is not just possible but inevitable. (2007, 9)
Well, sure -- one can solve any probabilistically daunting puzzle this way. Call it the Epicurean Escape Hatch. But there is precious little science, meaning knowledge, to be learned from these dumb luck scenarios. How did the replication-translation system come to be? Who knows? Spin the cosmic roulette wheel, and wait.
There is precious little science to be found, because the fundamental commitment of Dawkins and Koonin is not to empirical knowledge, but rather to naturalism. Dumb luck -- the Epicurean Escape Hatch -- is the naturalistic alternative to the unmistakable evidence of intelligent design revealed by even the smallest bacterial cell.
2. Nor does natural selection solve the problem of searching sequence space after life is present.
Here is a natural selection primer for anyone who has forgotten the basics of the theory. Selection operates only after a functional advantage occurs in some randomly arising variation. Until that happens, any search of sequence space necessarily will remain undirected -- meaning that the small probabilities cannot be escaped. No functional variation, no selection.
This unsolved problem has spawned an enormous literature within evolutionary biology, and represents one of the main reasons many biologists have quietly, or not so quietly, abandoned neo-Darwinian theory for more promising shores. Recently, Chatterjee et al. (2014) calculated the time required for the evolutionary process to search sequence space. Here's how they formulated the problem:
Throughout the history of life, evolution had to discover sequences of biological polymers that perform specific, complicated functions. The average length of bacterial genes is about 1000 nucleotides, that of human genes about 3000 nucleotides. The longest known bacterial gene contains more than 10^5 nucleotides, the longest human gene more than 10^6. A basic question is what is the time scale required by evolution to discover the sequences that perform desired functions.
Their model shows that, as the length L of the target sequence grows, the search time required grows exponentially, and quickly becomes intractable. As they conclude:
We show that adaptation on many fitness landscapes takes time that is exponential in L, even if there are broad selection gradients and many targets uniformly distributed in sequence space. These negative results lead us to search for specific mechanisms that allow evolution to work on polynomial time scales.
Whether their solution works, I leave as an exercise for the reader. But nota bene: natural selection is no help.
Dawkins wonders if Meyer thinks evolution is "easy to disprove." The answer is yes, but that doesn't explain why so many biologists nevertheless cast their lot with the theory.
I'll hazard a guess. Neo-Darwinian evolution is easy to disprove, but naturalism? That is, an a priori commitment to excluding evidence of intelligent design? That's a different story.
Chatterjee, Krishnendu et al. 2014. The Time Scale of Evolutionary Innovation. PLOS Computational Biology 10: e1003818.
Dawkins, Richard. 1987. The Blind Watchmaker. NY: W.W. Norton.
Koonin, Eugene. 2007. The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life. Biology Direct 2:15.