Does Evolution Explain Converging Ion Channels? Part 1
If evolutionary theory is true, scientists should not expect to see biological systems and features “repeated” in supposedly unrelated organisms—yet nature is replete with occurrences of such convergence. For example, recent studies of ion channels found similarities between mammalian brains and potatoes. These findings have dramatic implications. While they are surprising to anyone presuming naturalism, they are exactly what should be expected from a creation perspective.
Ion channels are fascinating structures composed of amino acids embedded within cell membranes. Among other functions, ion channels act as intracellular messengers and make muscle contractions possible. They form passages for ions (electrically charged atoms or groups of atoms) to travel in and out of cells. More importantly, due to ion channels’ role in energy production, life as we know it would not be possible without these complex structures. Recently, scientists have made some exciting discoveries about ion channels. These unexpected findings demonstrate that ion channels contain specificity that provides positive and convincing evidence for a divine Designer.
Cell Membranes 101
All eukaryotic cells are surrounded and protected by plasma membranes, which separate cells’ contents from their environment. Cell membranes are composed mainly of lipids (fats) that possess hydrophilic (water-loving) heads and hydrophobic (water-hating) tails.1 In water, layers of phospholipids come together with their heads pointed outward and their tails pointed inward. Single layers of phospholipids join together in water to form phospholipid bilayers.2 These bilayers protect the cell and attempt to control the traffic of molecules in and out of the cell.
Proteins contained throughout these bilayers perform various functions for the cell, including:
- functioning as receptors to communicate with the external environment;
- catalyzing chemical reactions inside and outside of cells;
- forming channels to shuttle molecules in, out, and across cell membranes; and
- even adding structural integrity to the membranes.3
At first, researchers believed that membrane proteins were disorganized and moved freely about cell bilayers.4 However, recent research has shown that the relationship between membranes and the proteins found within them is highly fine-tuned. Phospholipids bind to certain proteins and help activate them during signaling processes.5 The phospholipids also play a role in structurally supporting membrane proteins.6 Research has further shown that fine-tuned conditions must be met in order for membrane proteins to be inserted into the bilayers.7
This complexity is hard to explain through evolutionary means. Scientists have been tirelessly studying the inner workings of cell membranes and proteins. Yet these biochemical systems’ complexity continues to surprise researchers—as demonstrated by the recent findings on ion channels.
Mammal Brains and Potatoes
In the corporate world, valuable trade secrets—such as plans, programs, formulas, methods, procedures, and designs—are a highly sought advantage. Competitors recognize great designs when they see them and some will try to obtain them at any cost.
From a Christian perspective, God has a monopoly on creation and scientists continue to study His “trade secrets,” such as ion channels, in an attempt to better understand how they can be used for human benefit. To date, much has yet to be understood about the origins and inner workings of ion channels. But progress promises hope. Scientists have learned that ion channels in the membranes of both cells and mitochondria specialize in transporting different types of ions, such as potassium, chlorine, calcium, and sodium.8 By performing long-term mitochondrial research around the globe scientists hope to discover ways to reduce the effects of strokes and heart attacks.
Meanwhile, short-term advances are foreseen in the cosmetics industry.9 Scientists at the Nencki Institute of Experimental Biology of the Polish Academy of Sciences in Warsaw and the Institute of Molecular Biology and Biotechnology at Adam Mickiewicz University (AMU) are trying to develop new dermocosmetic (for precisely defined skin types) products by researching protective substances affecting mitochondrial potassium channels.10
In late 2011, the Nencki Institute scientists measured the currents that flow through the potassium channels in the mitochondria of potatoes and reached startling conclusions.They found that certain elements of membranes surrounding cellular mitochondria in potatoes are identical to those found in the brains of mammals.11 And not only do these potato proteins perform the same function as their mammalian counterparts, but they also react to the same toxins.12
What these scientists have found is something that evolutionary biologists call systemic molecular convergence. Convergence occurs on both molecular levels and at larger scales when biological systems or features are found to have arisen seemingly independently multiple times (echolocation in bats, dolphins, and shrews is a well-known example).13 There are five types of molecular convergence: functional, mechanistic, structural, sequential, and systemic.14 One of the first examples was discovered in 1943, when scientists found that yeast and rabbits shared the same fructose enzyme. Over the past decades scientists have discovered hundreds of other similar cases.15
Difficulties for the Evolutionary Paradigm
From an evolutionary perspective, it is difficult to account for the independent appearance of these systems in unrelated organisms. The intricacies and the time needed for fully functioning biochemical systems to evolve just once are astronomical. So when scientists started comparing the genomes of differing organisms, they did not expect to find any instances of molecular convergence.16 In 1943, such repetition was seen as an odd and rare case; today it is becoming the norm.
AMU scientist Wieslawa Jarmuszkiewicz says of the case of the potatoes and mammalian brains, “This is extraordinary. Proteins responsible for the transport of potassium ions seem to be evolutionarily preserved in the mitochondria.”17 In other words, for this discovery to make evolutionary sense, cell and organelle membranes in early organisms needed to develop in just the right way to accommodate ion channels somewhere between the hypothetical Last Universal Common Ancestor (LUCA) and the split between plant and animal cells.
However, it is very difficult to explain the origins of cell membranes and their proteins within a naturalistic paradigm. Though some researchers postulate that it was conceivable for the membrane components to self-assemble (under certain conditions and temperatures, lipids freely form into the bilayers needed for functioning membranes18), others argue that it is unlikely the required conditions for bilayers would exist or last long enough on early Earth.19 Also, lipids do not always form bilayers; they can form non-bilayer structures that are far from adequate for creating functioning membranes.20 Early Earth’s conditions aside, evolutionary theory must account for self assembly alongside the evolution of proteins located within the bilayers, which perform specific functions to allow cells to survive within the membrane.
As regards the proteins, the probability of the random formation of functioning proteins is astronomically high. In fact, research has determined that there has not been enough time since the universe began (13.7 billion years ago) for a functioning protein to form randomly. Taking the amount of time into account, the probability that a functioning protein will form at least 150 proteins in length is one chance in 1040,861.21
This fact by itself does not rule out the possibility of an evolutionary explanation.22 Other factors, such as functional equivalency (the ability of some functional proteins to be formed by different amino acid sequences), can effectively raise the possibility of the random protein formation.23 Nevertheless, a naturalistic explanation for the origin of proteins still faces significant problems. (For example, DNA is needed to make proteins yet proteins are needed to make DNA. Biochemist Fazale Rana explores this and other compelling issues in his book The Cell’s Design.)
The discovery by the Nencki Institute and AMU scientists only multiplies the difficulties encountered by an evolutionary perspective. The improbability of molecular convergence and the irreducible complexity of ion channels must be accounted for. Adam Szewczyk, a Nencki Institute researcher, explains a part of the predicament:
The problem with ion channels in the mitochondrial membranes is that they really should not exist at all. Modern models of energy production in the cell indicate that channels in mitochondrial membranes would lower the effectiveness of the process. But since the channels do exist, they must have provided significant evolutionary advantage. We, therefore, face the following question: when in the history of life on Earth has this advantage played a role?24
Jarmuszkiewicz believes that these mitochondrial ion channels should not exist in the first place because such systems would have needed to appear in simpler organisms prior to the theoretical evolutionary split into plants and animals. Yet simpler organisms did not require ion channels; thus, expending energy to operate the channels would have been an evolutionary disadvantage. In other words, organisms burdened with the drawback posed by new mitochondrial ion channels should not have survived alongside organisms without these channels.
It seems likely that more examples of molecular convergence will be uncovered as research continues. Of course, some will seek a naturalistic explanation in an attempt to reconcile molecular convergence with evolution. On the other hand, the existence of similar—and in some cases identical—biochemical systems and biomolecules easily provides positive evidence for a Creator. From a creation perspective, it makes sense to continually discover the same “schematics” across differing “products.” After all, human engineers do not completely redesign every single aspect of a product or system each time they develop something new. If they have a design that works well and is optimized, they will reuse it in each instance where it applies. Similarly, it could be argued that God reuses His designs across all types of life, regardless of their relation to one another.
In part 2 of this article series, I discuss two more examples of how ion channels support the case for the Creator.
1. Fazale Rana, The Cell’s Design (Grand Rapids: BakerBooks, 2008), 45.
3. Fazale Rana and Hugh Ross, Origins of Life (Colorado Springs: Navpress, 2004), 147.
4. Fazale Rana, The Cell’s Design (Grand Rapids: BakerBooks, 2008), 234.
5. Ibid., 228.
6. Ibid., 234.
7. Ibid., 232.
8. Nencki Institute of Experimental Biology, “Human Brain and the Potato: Similarities within the Mitochondrial Ion Channels,” ScienceDaily, posted December 13, 2011, http://www.sciencedaily.com/releases/2011/12/111201094255.htm.
13. Rana, The Cell’s Design, 206.
17. Nencki Institute, “Human Brain and the Potato,” http://www.sciencedaily.com/releases/2011/12/111201094255.htm.
18. Fazale Rana and Hugh Ross, Origins of Life (Colorado Springs: Navpress, 2004), 156.
19. Ibid., 158.
20. Ibid., 153.
21. Stephen C. Meyer, Signature in the Cell (New York: HarperCollins, 2009), 219.
22. Rana and Ross, Origins of Life, 139.
23. Fazale Rana, “Intelligent Design: The Right Conclusion, but the Wrong Reasons,” Today’s New Reason to Believe (blog), October 7, 2010, http:/ /www.reasons.org/articles/intelligent-design-the-right-conclusion-but-the-wrong-reasons.
24. Nencki Institute, “Human Brain and the Potato,” http://www.sciencedaily.com/releases/2011/12/111201094255.htm.
By Kyle Keltz
Kyle Keltz received his BBA in finance from Texas Tech University in 2010, and is currently earning his MA in apologetics (concentration in scientific apologetics) from Southern Evangelical Seminary in Matthews, North Carolina.