https://en.wikipedia.org/wiki/Irreducible_complexity#cite_note-84
Its interesting that Wiki provides as argument for macro change the fact that a research published in the peer-reviewed journal Nature showed that computer simulations of evolution demonstrated that it is possible for complex features to evolve naturally..This paper describes a computer simulation and thus contains no actual biology. So rather than provide evidence in the natural world, they resort to computer simulations.
following is the paper :
The evolutionary origin of complex features
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.
In the discussion section, we read: "Some readers might suggest that we 'stacked the deck' by studying the evolution of a complex feature that will be built on simpler features that were also useful. However, that is precisely what evolutionary theory requires..."
Well, no. The Lenski simulation requires that complex systems exhibiting complex functions can always be built up from simpler systems exhibiting simpler function . Macro change needs to explain many de novo features, like the arise of wings, legs, body organs etc, starting from biological systems which did not have such features at all.
"The simulation by Lenski et al. assumes that all functioning biological systems are evolutionary kludges of subsystems that presently have function or previously had function. But there's no evidence that real-life irreducibly complex biological machines, for instance, can be decomposed in this way. If there were, the Lenski et al. computer simulation would be unnecessary. Without it, their demonstration is an exercise in irrelevance.
Following are the main critique points :
1.Stacking the Deck: It was pre-ordained that the complex function can be created from the less complex functions (they hand-coded a solution before even running the simulation)--but there is no such guarantee in biology that subsystems can be so easily combined to produce anything useful! The complexity gap between the smaller functions (NAND, etc.) and the target functions (EQU) is not very big. In fact, they were able to create EQU using only 5 of the more primitive logic operation subsystems. This means that as far as logic is concerned, only 5 of the basic logic functions used in the programs are needed to evolve EQU. They created a simulation which they knew could evolve the target function through the subsystems. (This is why I have titled this critique "Evolution by Intelligent Design.")
2.Too Much Selective Advantage: Selective advantage was given to literally every single addition of logic functions in the organisms which evolved EQU. Additionally, every mutation which added code, always added functional line(s) of code, while in nature mutations are never guaranteed to have any meaning or functionality in the environment. This makes the evolution of EQU essentially inevitable, and it does not test irreducible complexity. In a true irreducibly complex system, there will be no selective advantage along an evolutionary pathway. In real world, there is no guarantee that the subsystems you need will necessarily give you a selective advantage along your evolutionary pathway.
3.Illustrating that Irreducible Complexity is Unevolvable: When the aforementioned "selective advantage" was taken away, and fitness only increased when the target function EQU appeared, EQU NEVER EVOLVED in their simulations! This is very significant because it shows that they modeled true irreducible complexity, and that when they did, irreducible complexity could not evolve!
Modeling Irreducible Complexity
The paper made one profound finding when it accurately modeled true irreducible complexity (first full paragraph, pg. 143). Michael Behe has defined irreducible complexity as:
"An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway." (A Response to Critics of Darwin’s Black Box, by Michael Behe, PCID, Volume 1.1, January February March, 2002; iscid.org/)
When Lenski et al. created a simulation with high irreducible complexity, i.e. there was no selective advantage until the target function arose, EQU never evolved! Consider this quote from the Lenski paper:
"At the other extreme, 50 populations evolved in an environment where only EQU was rewarded, and no simpler function yielded energy. We expected that EQU would evolve much less often because selection would not preserve the simpler functions that provide foundations to build more complex features. Indeed, none of these populations evolved EQU, a highly significant difference from the fraction that did so in the reward-all environment (P ~= 4.3 x 10-9, Fisher's exact test)."
In other words, when there is no selective advantage until you get the final function, the final function doesn't evolve. In this case, their simulation probably DID model biological reality because irreducible complexity claims that there is no advantage until you get the final function. In fact in such a scenario, it found that the evolution of such a structure was impossible. In other words, they just proved that irreducible complexity is unevolvable.
The Lenski paper can only be seen as a scientific response to the claims of ID proponents, published in a high profile journal such as Nature. Despite the fact that the authors of the Lenski paper would likely deny this fact, there are many clues which show that the article is intended as a rebuttal to the claims of ID proponents. Not only does this validate the work of ID proponents as posing a legitimate challenge to Darwin's theory, but it also indicates that the claims of ID proponents are eminently testable, falsifiable (though as discussed above, not yet falsified), and therefore also scientific in nature.
The article even attempts to address irreducible complexity without using the term. "Thus, although more than two dozen mutations were used to build EQU, undoing any one of them destroyed this function." They are stating that EQU was irreducibly complex, but yet it evolved. Thus, Exhibit C is as follows: the article directly purports to test the evolution of irreducible complexity but yet never uses the phrase. (Note: It is arguable that their stated conclusions about the evolution of irreducible complexity do not match the findings of their simulations. When EQU evolved, the study did not truly model irreducible complexity because it employed a "reward-all" environment where some function could be gained by adding parts which could also contribute to the final function. When the article properly modeled irreducible complexity, where only EQU was rewarded, EQU never evolved!)
While the author Carl Zimmer quotes co-author Christopher Adami to sing an over-inflated victory song, one important point should not be lost: this study implicitly proves that the claims of ID proponents, such the claim that some biological features are irreducible complexity, are eminently testable via the methods of science. Apparently Nature saw the claim of irreducible complexity as such a threat to evolution that it saw fit to publish a study which attempted to model the evolution of irreducible complexity.
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