Over my time as a dilettante observer of the science blogging community, I have noticed a certain frisson of controversy over the idea of random genetic drift. Sewall Wright, who with Ronald Fisher and J. B. S. Haldane (Bill Bryson’s observations on Haldane’s research into diving and decompression are entertaining) established the science of population genetics, is credited with coining the phrase in 1929. Thanks to Professor Joe Felsenstein for pointing out his seminal paper. Continue reading
The Lenski et al 2003 paper, The evolutionary origin of complex features, is really worth reading. Here’s the abstract:
A long-standing challenge to evolutionary theory has been whether it can explain the origin of complex organismal features. We examined this issue using digital organisms—computer programs that self-replicate, mutate, compete and evolve. Populations of digital organisms often evolved the ability to perform complex logic functions requiring the coordinated execution of many genomic instructions. Complex functions evolved by building on simpler functions that had evolved earlier, provided that these were also selectively favoured. However, no particular intermediate stage was essential for evolving complex functions. The first genotypes able to perform complex functions differed from their non-performing parents by only one or two mutations, but differed from the ancestor by many mutations that were also crucial to the new functions. In some cases, mutations that were deleterious when they appeared served as stepping-stones in the evolution of complex features. These findings show how complex functions can originate by random mutation and natural selection.
The thing about a computer instantiation of evolution like AVIDA is that you can check back every lineage and examine the fitness of all precursors. Not only that, but you can choose your own environment, and how much selecting it does. There are some really key findings:
…This brings us back to the UC Berkeley “Understanding Evolution” website. It abuses science in its utterly unfounded claim that “natural selection can produce amazing adaptations.”
In fact natural selection, even at its best, does not “produce” anything. Natural selection does not and cannot influence the construction of any adaptations, amazing or not. If a mutation occurs which improves differential reproduction, then it propagates into future generations. Natural selection is simply the name given to that process. It selects for survival that which already exists. Natural selection has no role in the mutation event. It does not induce mutations, helpful or otherwise, to occur. According to evolutionary theory every single mutation, leading to every single species, is a random event with respect to need.
He has forgotten what “adaptation” means. Of course he is correct that “Natural selection is simply the name given to [differential reproduction]”. And that (as far as we know), “every single mutation …is a random event with respect to need”.
And “adaptation” is the name we give to variants that are preferentially reproduced. So while he would be correct to say that “natural selection” is NOT the name we give to “mutation” (duh); it IS the name we give to the very process that SELECTS those mutations that promote reproduction. i.e. the process that produces adaptation.
Cornelius should spend more time at the Understanding Evolution website.
In the ‘Moderation’ thread, William J Murray tried to make a case for ideological bias among evolutionary scientists by referencing a 2006 Gil Dodgen post, in which numerous authors emphasise the lack of teleology within the evolutionary process. I thought this might merit its own OP.
I alluded in YEC part 2 that I didn’t believe the Phanerozoic fossil record (supposedly 500 million years ago) could stay intact since an erosion rate of 2.5 microns per year would erase a lot of it. There is a related complication.
[Thanks to Alan Fox for asking questions about YEC and Elizabeth Liddle for her generosity in hosting this discussion]
YEC part 1 gave some theological and philosophical context to the case for YEC, and part 2 will hopefully focus solely on empirical and scientific considerations. Part 2 challenges the mainstream view that the fossil record is hundreds of millions of years old.
Some of you are raring to go with responses to the Uncommon Descent post Dr. Ewert Answers. Adapa dropped the following into a thread in which I hope to engage Ewert in discussion of my own question, not Andy’s. Have fun.
Over at UD Ewert hand-waved away this question by Andy:
I’d like to start a thread about the proposition that features of the universe indicate that a designer designed and created it for a purpose.
We have had many such discussions on this blog previously, but I propose that in this thread we abide by a new rule: we will conduct the discussion solely in the form of English called E-prime:
E-Prime (short for English-Prime, sometimes denoted É or E′), a prescriptive version of the English language, excludes all forms of the verb to be. E-Prime does not allow the conjugations of to be—be, am, is, are, was, were, been, being—the archaic forms of to be (e.g. art, wast, wert), or the contractions of to be—’m, ‘s, ‘re (e.g. I’m, he’s, she’s, they’re).
Added June 17, 2015: Jump in with whatever comments you like, folks. Dr. Ewert has responded nebulously at Uncommon Descent. I’d have worked with him to get his meaning straight. I’m not going to spend my time on deconstruction. However, I will take quick shots at some easy targets, mainly to show appreciation to Lizzie for featuring this post as long as she has. Here, again, is what I put to Dr. Ewert:
Your “search” process decides when to stop and produce an outcome in the “search space.” A model may do this, but biological evolution does not. How do you measure active information on the biological process itself? Do you not reify a model?
Dr. Ewert seemingly forgets that to measure active information on a biological process is to produce a specific quantity, e.g., 109 bits.
One approach is to take the search space not to be the individual organisms, but rather the entire population of organisms currently alive on earth. Or one could go further, and take it to be the history of organisms during the whole of biological evolution. One could also take it to be possible spacetime histories. The target can then be taken to be spacetimes, histories, or populations that contain an individual organism type such as birds.
These “search spaces” roll off the tongue. But no one knows, or ever will know, what they actually contain. Even if we did know, no one would know the probabilities required for calculation of the active information for a given target. And even if we did know the probability of a given “target” for a given “search,” we would not be able to justify designating a particular probability distribution on the search space as the “natural” baseline. By the way, Dr. Ewert should not be alluding to infinite sets, as his current model of search applies only to finite sets.