"Evolution of Complexity. Molecular Aspects of Preassembly" review

Bard summary:

The paper "Evolution of Complexity. Molecular Aspects of Preassembly" by Fredric M. Menger and Syed A. A. Rizvi proposes a new model for the evolution of complex traits. The authors argue that, in addition to natural selection, there is another important mechanism that drives evolution: preassembly. Preassembly refers to the process by which genes and gene segments are assembled into functional units before they are needed. This process can occur over long periods of time, even before the trait itself is beneficial. Once the trait becomes beneficial, it can be further refined and improved through natural selection.

The authors support their model with evidence from a variety of sources. For example, they point to the fact that many complex traits, such as echolocation in bats and flowering plants, appear to have evolved very quickly. This suggests that natural selection alone cannot explain their evolution. The authors also point to the fact that many complex traits are encoded by non-coding genes. Non-coding genes do not directly code for proteins, but they can play important roles in controlling gene expression. The authors argue that non-coding genes are likely to be involved in preassembly.

The model of preassembly proposed by Menger and Rizvi has several implications for our understanding of evolution. First, it suggests that evolution is not always a slow and gradual process. In some cases, complex traits can evolve very quickly through a process of preassembly. Second, it suggests that natural selection is not the only important mechanism that drives evolution. Preassembly can create the raw materials that natural selection can then act on. Third, it suggests that non-coding genes play an important role in evolution. Non-coding genes are likely to be involved in preassembly, and they may play a role in the evolution of complex traits.

The model of preassembly proposed by Menger and Rizvi is a new and exciting development in our understanding of evolution. It provides a possible explanation for how complex traits can evolve quickly and why non-coding genes are important. The model is still in its early stages, but it has the potential to revolutionize our understanding of how life evolves.

Here are some additional thoughts on the paper:

1. The authors make a strong case for the importance of preassembly in evolution. They provide evidence from a variety of sources to support their argument.

2. The model of preassembly is still in its early stages, but it has the potential to revolutionize our understanding of how life evolves.

3. The model of preassembly could help us to better understand the evolution of complex traits, such as human intelligence.

4. The model of preassembly could also help us to develop new ways to treat genetic diseases.

Article snippets:

Evolution of Complexity. Molecular Aspects of Preassembly

10.3390/molecules26216618

An extension of neo-Darwinism, termed preassembly, states that genetic material required for many complex traits, such as echolocation, was present long before emergence of the traits.

Assembly of genes and gene segments had occurred over protracted time-periods within large libraries of non-coding genes.

Epigenetic factors ultimately promoted transfers from noncoding to coding genes, leading to abrupt formation of the trait via de novo genes.

This preassembly model explains many observations that to this present day still puzzle biologists: formation of super-complexity in the absence of multiple fossil precursors, as with bat echolocation and flowering plants; major genetic and physical alterations occurring in just a few thousand years, as with housecat evolution; lack of precursors preceding lush periods of species expansion, as in the Cambrian explosion; and evolution of costly traits that exceed their need during evolutionary times, as with human intelligence.

What follows in this paper is a mechanism that is not meant to supplant neo-Darwinism; instead, preassembly aims to supplement current ideas when complexity issues leave them struggling.

Echolocation systems in bats (Chiroptera) are complex “organs of perfection” enabling bats to locate and devour tiny, evasive insects in night-time flight

Only a portion of the >1000 bat species possess this skill. Toothed whales also make use of “biological sonar” but, since the two animals are not in any way related, their traits must have evolved by convergent evolution

The oldest known bat fossil dates back to the Eocene period about 52 million years ago

Clearly recognizable as a bat, this fossil put to rest a long-standing debate over which came first, flight or echolocation. The ancient bat was able to fly but made no use of echolocation, a fact evident from ear bones that were not enlarged as they are in modern bats that use echolocation.

Evolution of echolocation, per se, remains largely a mystery

Evolution of echolocation, per se, remains largely a mystery.

These words express neo-Darwinism’s main thesis. Clearly, the theory demands the presence of innumerable intermediates as one organism transforms into another. Yet, there exists no fossil evidence of creatures in the process of developing echolocation in a smooth continuous sequence.

Thus, there exists no fossil evidence of creatures with rudimentary echolocation in the process of becoming, step-by-step, the sophisticated systems found in bats

Be that as it may, no gradual improvements in echolocation development, from simple to complex and consistent with neo-Darwinism, have been found in Nature, past or present.

morphological diversity of modern bat skulls have probably been the closest evolutionists have come to addressing the mystery of bat lineages

After scanning this information, the reader is challenged to ponder how echolocation evolved in “infinitesimal steps” according to neo-Darwinian doctrine.

the reader is challenged to ponder how echolocation evolved in “infinitesimal steps” according to neo-Darwinian doctrine.

Prestin is a type of biological motor functioning at microsecond rates, orders of magnitude faster than any other cellular motor protein, at the outer hair cells of the inner ear. Information processing in the auditory cortex of the echolocator’s brains is also highly specialized in a manner not found in non-echolocating animals.

The total number of genes that a bat needs to create echolocation, and to guide its operation, is unknown

hundreds of genes are no doubt involved with echolocation, leaving evolutionists with the unanswered question, “How did they arise?

Thus, hundreds of genes are no doubt involved with echolocation, leaving evolutionists with the unanswered question, “How did they arise?”

clarification is needed regarding the time-sequence by which each component within the intricate structure made its individual appearance

no one can supply this essential information at the present time,

Discussion

let us now contrive a neo-Darwinian story describing how echolocation came into being.

let us now contrive a neo-Darwinian story describing how echolocation came into being.

Note that it was necessary for the story to propose a primitive echolocation capability from its very beginning. Otherwise, natural selection would obviously be unable to have promoted the occurrence of the trait

Apart from the difficulty of constructing a primitive, yet, functioning echolocation anatomy, other problems with the neo-Darwinian story are encountered.

In particular, how did echolocation, albeit a primitive form of it, originally appear among a population of bats totally lacking the trait?

A single new mutation, corresponding to one new protein, cannot easily be imagined as sufficient to create even a rudimentary echolocation ability.

A large but unknown number of concurrent mutations is likely needed to achieve even the simplest echolocation system.

A large but unknown number of concurrent mutations is likely needed to achieve even the simplest echolocation system

But mutations are rare and mainly harmful, so that an extended time-period must ensue before an entire family of mutations is ultimately acquired.

But mutations are rare and mainly harmful, so that an extended time-period must ensue before an entire family of mutations is ultimately acquired.

Yet, in a large population, the bat that receives the first echolocation mutation is statistically unlikely to be the bat that receives the second mutation or, for that matter, any of the others.

Consequently, the large number of echolocation genes would be distributed among an equal number of bats, none of whose genes would, by themselves, provide a functioning echolocation, however primitive

Echolocation would appear only if each gene disseminated into the population where it could mix efficiently and operate in concert with other related echolocation genes

In other words, the echolocation trait would take hold only if individual echolocation genes (whose initial stages are of no import to the bat) could nonetheless survive sufficiently long over a protracted time-period required by an excruciatingly slow series of “neutral” mutations.

To restate the problem faced by the neo-Darwinian scenario: Prior to the individual genes gathering into an intact “echolocation cluster,” the initial genes are for all intents and purposes assumed to be useless

To restate the problem faced by the neo-Darwinian scenario: Prior to the individual genes gathering into an intact “echolocation cluster,” the initial genes are for all intents and purposes assumed to be useless

But if the newly formed genes failed to manifest any benefit, then there was no obvious bio-criteria by which natural selection could favorably screen them

But if the newly formed genes failed to manifest any benefit, then there was no obvious bio-criteria by which natural selection could favorably screen them

The neo-Darwinian “one-tiny-mutation-at-a-time” mechanism leaves one perplexed as to how early echolocation mutations (genes that could not impart echolocation by themselves) would have been spread across the population by natural selection.

Bear in mind a basic tenet of neo-Darwinism: the mechanism is not predictive of future capabilities. Natural selection would not have fostered genes whose utility manifested itself only eons after the genes’ actual appearances.

Bear in mind a basic tenet of neo-Darwinism: the mechanism is not predictive of future capabilities

Natural selection would not have fostered genes whose utility manifested itself only eons after the genes’ actual appearances.

In other words, secondary factors “dragged” echolocation along with them. It is difficult to comment on this rationale because, for one reason, possible secondary functions in echolocation evolution have not been established.

Let it simply be stated here that attributing an unknown pathway to the success of another unrelated pathway, also unknown, seems nonproductive

Let it simply be stated here that attributing an unknown pathway to the success of another unrelated pathway, also unknown, seems nonproductive

neo-Darwinian mechanism states that bat echolocation evolution continued unabated until hundreds of mutations, each of them beneficial to the cause, were gathered in at least one individual

A neo-Darwinian mechanism states that bat echolocation evolution continued unabated until hundreds of mutations, each of them beneficial to the cause, were gathered in at least one individual.

This brings up another drawback to the construct—time—as illustrated by two questions

How long must a proposed intermediate wait until it is modified (beneficially, of course) by rare, random, and usually harmful mutational forces?

(1) How long must a proposed intermediate wait until it is modified (beneficially, of course) by rare, random, and usually harmful mutational forces? Note that this question does not ask for general mutation rates but, instead, the probability of an extended series of specifically needed mutations occurring in exactly the correct sequence.

this question does not ask for general mutation rates but, instead, the probability of an extended series of specifically needed mutations occurring in exactly the correct sequence.

How long will it take for natural selection to expand the presence of new mutations throughout a population, especially if the mutation is only mildly beneficial within slowly reproducing and migrating animals?

Since a minimum of several hundred mutations are associated with echolocation, the time requirements for these all these mutation/mixing events would have been immense.

Since a minimum of several hundred mutations are associated with echolocation, the time requirements for these all these mutation/mixing events would have been immense.

A crude sense of the time requirements can be obtained from the Genetics publication of Durrett and Schmidt who calculated the waiting time for a pair of pre-specified mutations

The results, which are strongly dependent upon a series of reasonable assumptions (concerning nucleotide mutation rate, population, neutrality of mutations etc.), show that the second specific mutation appears after a wait of 9 million years!

The point of this is not to provide exact numbers, as much as to show that an evolution advancing in “infinitesimal steps” is horrendously slow, especially during early stages when mutations are “neutral”, i.e., they provide no survival advantage

Evolutionists are well aware of the statistical problems just mentioned

neo-Darwinism must assume a myriad of tiny accessible steps, each of them being increasingly profitable to the organism [13]. But the lack of discrete intermediates in echolocation, demanded by this mechanism, discredits such a proposal.

Examples of evolutionary changes at odds with the conventional neo-Darwinism have been published previously

Echolocation and the four additional evolutionary riddles are far too widespread, diverse, and profound to be casually dismissed as “anomalies” or “rare exceptions”

A more broadly based evolutionary theory, one that includes a faster and less “piecemeal” structure-development, is called for.

Such alterations, however, fall under the category of “microevolution” and involve simple one gene/one enzyme modifications

Alternative models are needed especially with the complex systems, such as those just cited, where neo-Darwinism is deficient in explaining large numbers of interconnected modifications for which relevant intermediates are absent.