In an earlier article we looked at numerous features exhibiting design in the origin and deposition of metals and metal ores, resulting in their accessibility for human utilization. Here we’ll explore some of the deeply imbedded connections between metals and life.

One of the most fundamental aspects of all life is the ability to derive energy from metabolic processes, notably dependent upon fractional amounts of metal atoms integrated within cellular biochemistry.

Life is based on energy gained by electron-transfer processes; these processes rely on oxidoreductase enzymes, which often contain transition metals in their structures….Oxygenic photosynthesis appeared between 3.2 and 2.5 billion years ago, as did methane oxidation, nitrogen fixation, nitrification and denitrification. These metabolisms rely on an expanded range of transition metals presumably made available by the build-up of molecular oxygen in soil crusts and marine microbial mats. The appropriation of copper in enzymes before the Great Oxidation Event is particularly important, as copper is key to nitrogen and methane cycling and was later incorporated into numerous aerobic metabolisms.¹

In reading such descriptive statements, it’s important not to naïvely assume that undirected natural forces have the prescience and ability, through luck or determination, to develop the complex biochemistry involved in producing enzymes, photosynthetic reactions, or other metabolic activities.

The Role of Metals

The crucial role of metals in enzymatic reactions is causally suspect from a naturalistic perspective but is consistent with characteristics of sophisticated engineering designs. In highly designed systems, each of multiple parts in the whole functional system is indispensable and must perform within strict tolerances. Researchers have affirmed that metals play just such an indispensable role in numerous biological processes.

• “In all metalloenzymes, removal of the metal component causes loss of activity.”²
• “Cu-containing oxidases mediate a wide range of important oxidation reactions in nature….”³
• “Molybdenum is a trace metal required by virtually every species….”⁴
• “Selenium also plays an important role as a nutrient, being a component of the amino acid selenocysteine (Sec), through which it is incorporated in enzymes requiring this metal as cofactor.”⁵

Biologically important enzymes often require the efficacious properties of metal atoms, which comprise less than a tenth of a percent of their total number of constituent atoms.

Some essential heavy metals including chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), and zinc (Zn) have vital biochemical and physiological roles in animals and plants at low concentrations. These trace metals are significant constituents of some critical enzymes involved in redox reactions, biosynthesis, transport, and other metabolic activities.⁶

Consider that a functional metalloenzyme consists of several thousand atoms, primarily hydrogen and carbon, along with oxygen, nitrogen, and sulfur.  But, for the complex biomolecule to function, it must also incorporate about a few metal ions, bonded appropriately within a matrix of organic amino acids. For example, the N₂0 reductase enzyme contains “four copper atoms forming a distorted tetrahedral geometry, with an inorganic sulfur ion (S^2-) as a bridging ligand.”⁷

The hemoglobin molecule contains about 10,000 atoms overall, but just four iron atoms that play an exquisitely essential role in the transfer of oxygen in our bloodstream.

Microbes, Metals, and Life

The interactions between metals and living organisms has also produced the beneficial effect of increasing the habitability of Earth for more advanced life.

Microbes affect dissolution, transformation and formation of minerals through metabolic activities. These interactions between minerals and microbes substantially determine the habitability of the Earth.⁸

For example, an inter-connection between metals and life supplied us with vast, accessible layers of iron ore. Photosynthetic bacteria in the early Earth’s oceans (3.5 billion to 1.8 billion years ago) produced oxygen that combined with dissolved oceanic iron.

Oxygen then reacted with the soluble iron to form insoluble iron oxide. Iron oxides fell to the ocean floors as minerals like magnetite and hematite. These sediments continued to accumulate in alternating bands on the ocean floors. They created the banded formations or BIF we now find.⁹

Studies reveal that, over the course of the existence of microbial life on the early Earth, microbes incorporated different metal cofactors for essential metabolic activities.

Mineral–microbe interactions play important roles in environmental change, biogeochemical cycling of elements and formation of ore deposits….Through these interactions, minerals and microbes co-evolve through Earth history.

Another Just-So Story 

The evolutionary mindset swallows all evidence and digests it into another just-so story of mindless chemical interactions fabricating novel adaptations to overcome environmental challenges. Although the authors say that “minerals and microbes co-evolve through Earth history,” the naturalistic inability to generate new, complex, functional metabolic pathways suggests, rather, that intelligent design plays the role of adapting microbial life to changing environmental conditions. 

Almost half of enzymes require metals, and metalloproteins tend to optimally utilize the physicochemical properties of a specific metal co-factor. Life must adapt to changes in metal bioavailability, including those during the transition from anoxic to oxic Earth or pathogens’ exposure to nutritional immunity. These changes can challenge the ability of metalloenzymes to maintain activity, presumptively driving their evolution.¹⁰

If enzymes utilizing specific essential metal co-factors have the ability to “adapt to changes in metal bioavailability,” then this adaptability speaks more powerfully of sophisticated engineering design than a random struggle to “make do” when scarcity threatens continued existence. 

Balancing Metals on a Knife-Edge

Further evidence for design comes from the complementary conditions for life’s requirements for a wide range of trace metals in the Earth’s crust, while avoiding life’s fatal vulnerability to excessive concentrations of most of these same metals.

Copper is the cofactor of important enzymes responsible for redox reactions, including…enzymes for iron metabolism, among many others. Because it is highly toxic in concentrations outside the physiological range, all microorganisms possess systems for controlling its homeostasis by regulating influx and efflux and producing copper-binding proteins that readily complex the free copper.¹¹

It’s axiomatic that developing “systems for controlling its homeostasis” is neither straightforward nor guaranteed by unguided natural processes, and yet “all microorganisms” possess these complex, functional systems. As a physicist, nothing in my study of the forces governing the interactions of atomic particles suggests that such specific, complex, functional biochemical processes would result from electric forces acting on charged particles (the essence of all chemical reactions). No amount of “need to survive” can change this conclusion.

A Precise Balancing Act

Of the ten or so metal elements essential for life, regulating their amounts in a living organism demands a precise balancing act.

• “Either a deficiency, or an excess of essential metals may result in various disease states arising in an organism.”¹²
• “Indeed, some of them [metals and minerals] are so important that we can’t live without them….We don’t manufacture essential minerals in the body. We get them from our diet. The minerals come from rocks, soil, and water, and they’re absorbed as the plants grow or by animals as the animals eat the plants.”¹³

For essential metals and minerals to be absorbed by plants points to the necessity of finely tuned amounts of these elements to exist in the topsoil of Earth’s crust. Too much or too little of these elements in the soil would have repercussions throughout the food chain, negatively affecting our health.

Dr. Bruce Bistrian, chief of clinical nutrition at Beth Israel Deaconess Medical Center, says,

Each one plays a role in hundreds of body functions. It may take just a very small quantity of a particular mineral, but having too much or too little can upset a delicate balance in the body.¹⁴

The complementary interaction between metals and life provides yet another example of our existence relying upon multiple levels of design — from stars to planet Earth and from cells to human life.

Notes

1. Metal availability and the expanding network of microbial metabolisms in the Archaean eon | Nature Geoscience. Moore, E., Jelen, B., Giovannelli, D. et al. Metal availability and the expanding network of microbial metabolisms in the Archaean eon. Nature Geosci 10, 629–636 (2017). https://doi.org/10.1038/ngeo3006.
2. Antonio Blanco, Gustavo Blanco, in Medical Biochemistry, 2017.
3. Scott D. McCann and Shannon S. Stahl, “Copper-Catalyzed Aerobic Oxidations of Organic Molecules,” Acc. Chem. Res. 2015, 48, 6, 1756–1766 (May 28, 2015). https://doi.org/10.1021/acs.accounts.5b00060.
4. Elisabetta Bini, Archaeal transformation of metals in the environment, FEMS Microbiology Ecology, Volume 73, Issue 1, July 2010, Pages 1–16, https://doi.org/10.1111/j.1574-6941.2010.00876.x
5. Elisabetta Bini, FEMS Microbiology Ecology, Volume 73, Issue 1, July 2010.
6. Haidar Z, Fatema K, Shoily SS, Sajib AA. Disease-associated metabolic pathways affected by heavy metals and metalloid. Toxicol Rep. 2023 Apr 24;10:554-570. doi: 10.1016/j.toxrep.2023.04.010.
7. Lin Y. W. Rational Design of Artificial Metalloproteins and Metalloenzymes with Metal Clusters. Molecules. 2019 Jul 29; 24(15): 2743. doi: 10.3390/molecules24152743.
8. A critical review of mineral–microbe interaction and co-evolution: mechanisms and applications – PMC (nih.gov)
9. https://www.csiro.au/en/news/all/articles/2024/march/banded-iron-formations
10. Sendra, K.M., Barwinska-Sendra, A., Mackenzie, E.S. et al. “An ancient metalloenzyme evolves through metal preference modulation.” Nat Ecol Evol 7, 732–744 (2023). https://doi.org/10.1038/s41559-023-02012-0.
11. Elisabetta Bini, FEMS Microbiology Ecology, Volume 73, Issue 1, July 2010.
12. Jomova K, Makova M, Alomar SY, Alwasel SH, Nepovimova E, Kuca K, Rhodes CJ, Valko M. Essential metals in health and disease. Chem Biol Interact. 2022 Nov 1;367:110173. 
    doi: 10.1016/j.cbi.2022.110173. Epub 2022 Sep 22. PMID: 36152810.
13. https://www.health.harvard.edu/staying-healthy/precious-metals-and-other-important-minerals-for-health.
14. https://www.health.harvard.edu/staying-healthy/precious-metals-and-other-important-minerals-for-health.