Interdependence in biology

Interdependence in biology

http://www.rae.org/pdf/interdep.pdf

A gasoline engine "comes to life" only when many different independent conditions are met at the same time. Take away the spark plug, and it will not run at all. Leave out the pistons, and it will not run. Without oil or gasoline, it will not run. The list of interdependent conditions goes on and on. Even if all other conditions are met, it must be given an initial crank in order to start. Likewise, living creatures have inter-dependent characteristics which determine their very existence. Photosynthesis does not work without the conversion of energy into enzymatic and dark reaction cicle activity.

Compared to photosynthesis, a gasoline engine is extremely primitive. In order for photosynthesis to arise spontaneously, the sum of the parts of enzymes, genes, proteins , and protein complexes  would have to come together intact in order to function, and the chemical reactions which would produce glucose would have to be started all at once.


http://reasonandscience.heavenforum.org/t1468-irreducible-complexity#2133

What type of biological system could not be formed by “numerous successive, slight modifications?” Well, for starters, a system that is irreducibly complex.

By irreducibly complex I mean a single system composed of several well-matched interacting parts that contribute to the basic function, wherein the removal of any one of the [core] parts causes the system to effectively cease functioning.


But today, there are many such cases observed in nature.

High information content machine-like irreducibly complex and interdependent structures, of which photosynthesis, the eye, the human body, nitrogenase, the ribosome, the cell, rubisco, photosystem II, the oxygen evolving complex etc. are prime examples, are commonly found in nature.
Since Evolution is unable to provide a advantage of adaptation in each evolutionary step, 1) Darwinism’s prediction is falsified; 2) Design’s prediction is confirmed.

Irreducible Complexity and Interdependence in Biological Systems: Challenges to Evolutionary Theory

Irreducible complexity and interdependence are related concepts, but they have distinct meanings and implications, especially in the context of biological systems and network theory. Let's examine each concept:

Irreducible complexity:

1. Definition: A system is considered irreducibly complex if it consists of several interacting parts, all of which are necessary for the system to function.
2. Origin: This concept was popularized by biochemist Michael Behe, particularly in discussions about evolution and intelligent design.
3. Key aspect: The removal of any single component renders the entire system non-functional.
4. Example: Behe used the bacterial flagellum as an example, arguing that all its parts are necessary for it to function, and it couldn't have evolved gradually.
5. Controversy: This concept is widely criticized in the scientific community, as many seemingly irreducibly complex systems have been shown to have evolutionary pathways.

Interdependence:

1. Definition: Interdependence refers to the mutual reliance between two or more components, systems, or networks.
2. Scope: This concept is broader and applies to many fields, including biology, ecology, economics, and network science.
3. Key aspect: Components in an interdependent system influence each other, but the system may still function (perhaps sub-optimally) if some components are removed or altered.
4. Degrees: Interdependence can vary in strength and nature, from loose coupling to tight integration.
5. Example: In the paper discussed, the gene regulatory network and metabolic network are described as interdependent systems in cells.

Key differences:

1. Functionality: Irreducible complexity implies complete loss of function if any part is removed, while interdependent systems may continue functioning, albeit differently, if some parts are altered.
2. Flexibility: Interdependent systems often have more flexibility and can adapt to changes, while irreducibly complex systems are theoretically inflexible.
3. Scientific acceptance: Interdependence is a widely accepted concept in various scientific fields, while irreducible complexity is generally not accepted in mainstream biology.
4. Scope of application: Interdependence is a broader concept applicable to many types of systems, while irreducible complexity is mainly used in arguments about biological structures.

The evolution of highly interdependent systems poses a challenge to evolutionary theory. If two systems are completely dependent on each other to function, it does raise the question of how they could have evolved separately.
Many evolutionary biologists argue that interdependence typically evolves gradually. Systems don't start out fully interdependent, but rather become increasingly intertwined over time. But for example, genes and their regulatory networks are deeply interdependent, and it's hard to conceive of one existing without the other in any meaningful way. Genes without regulation would be constantly active, wasting resources, while regulatory elements without genes to control would be functionless. This situation presents a classic "chicken and egg" problem in molecular evolution. How could such interdependent systems have evolved if neither has function without the other? Studies on minimal genomes suggest that even the simplest self-replicating cells require a complex set of interacting genes and regulatory elements.

The claim that genes and regulatory networks co-evolved, rather than evolving separately and then becoming interdependent, is indeed a hypothesis made. However, it's important to critically examine this claim and recognize that it may be oversimplified or potentially a "just-so story."  There's no direct fossil or molecular evidence that conclusively proves this co-evolution scenario. It's largely based on inference and extrapolation from current biological systems.
The interdependence between genes and regulatory networks is extremely complex. It's difficult to imagine how such systems could have arisen simultaneously without precursor components

David, F., Klosik. (2017). The interdependent network of gene regulation and metabolism is robust where it needs to be. 
https://www.nature.com/articles/s41467-017-00587-4

The two main interdependent systems described are:

1. Gene regulatory network
2. Metabolic network

The paper focuses on studying these two major biochemical networks of living cells as an interdependent system, rather than as separate networks as they have often been approached before.  Specifically, the article states:
"Despite being highly interdependent, the major biochemical networks of the living cell—the networks of interacting genes and of metabolic reactions, respectively—have been approached mostly as separate systems so far."
The authors argue that these two networks are highly interconnected and dependent on each other:

- The gene regulatory network influences the metabolic network through enzyme catalysis of biochemical reactions.
- The metabolic network influences the gene regulatory network through the activation or deactivation of transcription factors by certain metabolic compounds.

Commentary: The high degree of interdependence between the gene regulatory network and the metabolic network makes it very improbable that these systems evolved separately for several reasons: The two networks are deeply intertwined in their functions. Gene regulation produces enzymes necessary for metabolism, while metabolites influence gene expression. This tight coupling suggests co-creation rather than independent development. In isolation, neither network would serve a meaningful purpose. A gene regulatory network without metabolism to influence would be directionless, while a metabolic network without gene regulation would be static and unable to adapt to environmental changes.
The described system relies heavily on feedback mechanisms between the two networks. These feedback loops are critical for cellular homeostasis and adaptation. It's difficult to envision how such feedback systems could arise if the networks evolved separately. The interdependence allows for fine-tuned control and resource allocation within cells. This level of optimization suggests a co-created system rather than two independently optimized systems that happened to work well together. There would be little selective advantage for either system to evolve independently to such complexity without the functional benefits provided by their interaction. Many core metabolic pathways and gene regulatory mechanisms are highly conserved across diverse life forms, suggesting ancient origins and co-creation. It's challenging to conceive of functional intermediate evolutionary states that would bridge the gap between separate systems and the highly integrated network we observe. The specific interactions between metabolites and transcription factors, and between genes and enzymes, imply a level of complexity that is more consistent with co-creation than with independent evolutionary development. Given these considerations, it's more plausible that these networks were co-created,  rather than evolving as separate entities that later became integrated. The functional unity of the system strongly suggests creation by an intelligent agent with foresight, and purposeful functions of the integrated system in sight.