Membrane Biochemistry Challenges Route to Evolutionary Origin of Complex Cells

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By Fazale Rana – July 10, 2019

Unfortunately, the same thing could be said to biologists trying to discover the evolutionary route that led to the emergence of complex, eukaryotic cells. No matter the starting point, it seems as if you just can’t get there from here.

This frustration becomes most evident as evolutionary biologists try to account for the biochemical makeup of the membranes found in eukaryotic cells. In my opinion, this struggle is not just an inconvenient detour. As the following paragraphs show, obstacles line the roadway, ultimately leading to a dead end that exposes the shortcomings of the endosymbiont hypothesis—a cornerstone idea in evolutionary biology.

Endosymbiont Hypothesis

Most biologists believe that the endosymbiont hypothesis stands as the best explanation for the origin of complex cells. According to this hypothesis, complex cells originated when symbiotic relationships formed among single-celled microbes after free-living bacterial and/or archaeal cells were engulfed by a “host” microbe.

The mitochondrion represents the “poster child” of the endosymbiont hypothesis. Presumably, this organelle started as an endosymbiont. Evolutionary biologists believe that once engulfed by the host cell, the microbe took up permanent residency, growing and dividing inside the host. Over time, the endosymbiont and host became mutually interdependent, with the endosymbiont providing a metabolic benefit—such as a source of ATP—for the host cell. In turn, the host cell provided nutrients to the endosymbiont. Presumably, the endosymbiont gradually evolved into an organelle through a process referred to as genome reduction. This reduction resulted when genes from the endosymbiont’s genome were transferred into the genome of the host organism.

Evidence for the Endosymbiont Hypothesis
1. Most of the evidence for the endosymbiont hypothesis centers around mitochondria and their similarity to bacteria. Mitochondria are about the same size and shape as a typical bacterium and have a double membrane structure like gram-negative cells. These organelles also divide in a way that is reminiscent of bacterial cells.

2. Biochemical evidence also exists for the endosymbiont hypothesis. Evolutionary biologists view the presence of the diminutive mitochondrial genome as a vestige of this organelle’s evolutionary history. They see the biochemical similarities between mitochondrial and bacterial genomes as further evidence for the evolutionary origin of these organelles.

3. The presence of the unique lipid, cardiolipin, in the mitochondrial inner membrane also serves as evidence for the endosymbiont hypothesis. This important lipid component of bacterial inner membranes is not found in the membranes of eukaryotic cells—except for the inner membranes of mitochondria. In fact, biochemists consider it a signature lipid for mitochondria and a vestige of the organelle’s evolutionary history. So far, the evolutionary route looks well-paved and clear.

Discovery of Lokiarchaeota

Evolutionary biologists have also developed other lines of evidence in support of the endosymbiont hypothesis. For example, biochemists have discovered that the genetic core (DNA replication and the transcription and translation of genetic information) of eukaryotic cells resembles that of the archaea. This similarity suggests to many biologists that a microbe belonging to the archaeal domain served as the host cell that gave rise to eukaryotic cells.

Life scientists think they may have determined the identity of that archaeal host. In 2015, a large international team of collaborators reported the discovery of Lokiarchaeota, a new phylum belonging to the archaea. This phylum clusters with eukaryotes on the evolutionary tree. Analysis of the genomes of Lokiarchaeota identifies a number of genes involved in membrane-related activities, suggesting that this microbe may well have possessed the ability to engulf other microbes.1 At this point, it looks like “you can get there from here.”

Challenges to the Endosymbiont Hypothesis

Despite this seemingly compelling evidence, the evolutionary route to the first eukaryotic cells is littered with potholes. I have written several articles detailing some of the obstacles. (See Challenges to the Endosymbiont Hypothesis in the Resources section.) Also, a divide on the evolutionary roadway called the lipid divide compounds the problem for the endosymbiont hypothesis.

Lipid Divide

The lipid divide refers to the difference in the chemical composition of the cell membranes found in bacteria and archaea. Phospholipids comprise the cell membranes of both sorts of microbes. But the similarity ends there. The chemical makeup of the phospholipids is distinct in bacteria and archaea.

Bacterial phospholipids are built around a d-glycerol backbone, which has a phosphate moiety bound to the glycerol in the sn-3 position. Two fatty acids are bound to the d-glycerol backbone at the sn-1 and sn-2 positions. In water, these phospholipids assemble into bilayer structures.

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Figure: Difference between archaeal (top) and bacterial (middle and bottom) phospholipids. Features include 1: isoprene chains, 2: ether linkage, 3: l-glycerol, 4 and 8: phosphate group, 5: fatty acid chains, 6: ester linkages, 7: d-glycerol, 9: lipid bilayer of bacterial membranes, 10: lipid monolayer found in some archaea. Image credit: Wikipedia

Archaeal phospholipids are constructed around an l-glycerol backbone (which produces membrane lipids with different stereochemistry than bacterial phospholipids). The phosphate moiety is attached to the sn-1 position of glycerol. Two isoprene chains are bound to the sn-2 and sn-3 positions of l-glycerol via ether linkages. Some archaeal membranes are formed from phospholipid bilayers, while others are formed from phospholipid monolayers.

Presumably, the structural features of the archaeal phospholipids serve as an adaptation that renders them ideally suited to form stable membranes in the physically and chemically harsh environments in which many archaea find themselves.

Lipid Divide Frustrates the Origin of Eukaryotic Cell Membranes

In light of the lipid divide and the evidence that seemingly indicates that the endosymbiotic host cell likely belonged to Lokiarchaeota, it logically follows that the membrane composition of eukaryotic cells should be archaeal-like. But, this expectation is not met and the evolutionary route encounters another pothole. Instead, the cell membranes of eukaryotic cells closely resemble bacterial membranes.

One way to repair the roadway is to posit that during the evolutionary process that led to the emergence of eukaryotic cells, a transition from archaeal-like membranes to bacterial-like membranes took place. In fact, supporting evidence comes from laboratory studies demonstrating that stable bilayers can form from a mixture of bacterial and archaeal phospholipids, even though the lipids from the two sources have opposite stereochemistry.

Evolutionary biologists Purificación López-García and David Moreira question if evidence can be marshaled in support of this scenario for two reasons.2 First, mixing of phospholipids in the lab is a poor model for cell membranes that function as a “dynamic cell-environment interface.”3

Second, they question if this transition is feasible given how exquisitely optimized membrane proteins must be to fit into cell membranes. The nature of protein optimization is radically different for bacterial and archaeal membranes. Because cell membrane systems are optimized, the researchers question if an adequate driving force for this transition exists.

In other words, these two scientists express serious doubts about the biochemical viability of a transitional stage between archaeal membranes. In light of these obstacles, López-García and Moreira write, “The archaea-to-bacteria membrane shift remains the Achilles’ heel for these models [that propose an archaeal host for endosymbionts].”4

In other words, you can’t get there from here.

Can Lokiarchaeota Traverse the Lipid Divide?

In the midst of this uncertain evolutionary route, a recent study by investigators from the Netherlands seems to point the way toward the evolutionary origin of eukaryotic membranes.5 Researchers screened the Lokiarchaeota genome for enzymes that would take part in phospholipid synthesis with the hope of finding clues about how this transition may have occurred. They conclude that this group of microbes could not make l-glycerol-1-phosphate (a key metabolic intermediate in the production of archaeal phospholipids) because it lacked the enzyme glycerol-1-phosphate dehydrogenase (G1PDH). They also discovered evidence that suggests that this group of microbes could make fatty acids and chemically attach them to sugars. The researchers argue that Lokiarchaeota could make some type of hybrid phospholipid with features of both archaeal and bacterial phospholipids.

The team’s approach to understanding how evolutionary processes could bridge the lipid divide and account for the origin of eukaryotic membranes is clever and inventive, to be sure. But it is far from convincing for at least four reasons.

1. Absence of evidence is not evidence of absence, as the old saying goes. Just because the research team didn’t find the gene for G1PDH in the Lokiarchaeota genetic material doesn’t mean this microbe didn’t have the capacity to make archaeal-type phospholipids. Toward this end, it is important to note that researchers have not cultured any microbe that belongs to this group organisms. The group’s existence is inferred from metagenomic analysis, which involves isolating small fragments of DNA from the environment (in this case a hydrothermal vent system in the Atlantic Ocean, called Loki’s Castle) and stitching them together into a genome. The Lokiarchaeota “genome” is low quality (1.4-fold coverage) and incomplete (8 percent of the genome is missing). Around one-third (32 percent) of the genome codes for proteins with unknown function. Could it be that an enzyme capable of generating l-glycerol-1-phosphate exists in the mysterious third of the genome? Or in the missing 8 percent?

2. While the researchers discovered that genes could conceivably work together to make d-glycerol-3-phosphate (though the enzymes encoded by these genes perform different metabolic functions), they found no direct evidence that Lokiarchaeota produces d-glycerol-3-phosphate. Nor did they find evidence for glycerol-3-phosphate dehydrogenase (G3PDH) in the Lokiarchaeota genetic material. This enzyme plays a key role in the synthesis of phospholipids in bacteria.

3. Though the researchers found evidence that Lokiarchaeota had the capacity to make fatty acids, some of the genes required for the process seem to have been acquired by these microbes via horizontal gene transfer with genetic material from bacteria. (It should be noted that 29 percent of the Lokiarchaeota genome comes from the bacteria.) It is not clear when Lokiarchaeota acquired these genes and, therefore, if this metabolic capability has any bearing on the origin of eukaryotes.

4. The researchers present no evidence that Lokiarchaeota possessed the protein machinery that would chemically attach isoprenoid lipids to d-glycerol-3-phosphate via ether linkages.

Thus, the only way to establish Lokiarchaeota membranes as a transitional evolutionary pathway between those found in Archaea and Bacteria is to perform chemical analysis of its membranes. At this juncture, such analysis is impossible to perform because no one has been able to culture Lokiarchaeota. In fact, other evidence suggests that this group of microbes possessed archaeal-type membranes. Researchers have recovered archaeal lipids in the sediments surrounding Loki’s Castle, but they have not recovered bacterial-like lipids.

More Lipid Divide Frustration

Given these problems, could it be that the host microbe for the endosymbiont was a member of Bacteria, not Archaea? While this model would solve the problem of the lipid divide, it leaves unexplained the similarity between the genetic core of eukaryotes and the Archaea. Nor does it account for the grouping of eukaryotes with the Archaea.

It doesn’t look like you can get there from here, either.

Evolutionary biologists Jonathan Lombard, Purificación López-García and David Moreira sum things up when they write, “The origin of eukaryotic membranes is a problem that is rarely addressed by the different hypotheses that have been proposed to explain the emergence of eukaryotes.”6 Yet, until this problem is adequately addressed, the evolutionary route to eukaryotes will remain obscure and the endosymbiont hypothesis noncompelling.

In light of this challenge and others, maybe a better way to make sense of the origin of eukaryotic cells is to view them as the Creator’s handiwork. For many scientists, it is a road less traveled, but it accounts for all of the data. You can get there from here.

Resources

Challenges to the Endosymbiont Hypothesis

Support for a Creation Model for the Origin of Eukaryotic Cells

Endnotes
  1. Anja Spang et al., “Complex Archaea that Bridge the Gap between Prokaryotes and Eukaryotes,” Nature 521 (May 14, 2015): 173–79, doi:10.1038/nature14447; Katarzyna Zaremba-Niedzwiedzka et al., “Asgard Archaea Illuminate the Origin of Eukaryotic Cellular Complexity,” Nature 541 (January 19, 2017): 353–58, doi:10.1038/nature21031.
  2. Purificación López-García and David Moreira, “Open Questions on the Origin of Eukaryotes,” Trends in Ecology and Evolution 30, no. 11 (November 2015): 697–708, doi:10.1016/j.tree.2015.09.005.
  3. López-García and Moreira, “Open Questions.”
  4. López-García and Moreira, “Open Questions.”
  5. Laura Villanueva, Stefan Schouten, and Jaap S. Sinninghe Damsté, “Phylogenomic Analysis of Lipid Biosynthetic Genes of Archaea Shed Light on the ‘Lipid Divide,’” Environmental Microbiology 19, no. 1 (January 2017): 54–69, doi:10.1111/1462-2920.13361.
  6. Jonathan Lombard, Purificación López-García, and David Moreira, “The Early Evolution of Lipid Membranes and the Three Domains of Life,” Nature Reviews Microbiology 10 (June 11, 2012): 507–15, doi:10.1038/nrmicro2815.

Reprinted with permission by the author

Original article at:
https://reasons.org/explore/blogs/the-cells-design

Do Plastic-Eating Bacteria Dump the Case for Creation?

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BY FAZALE RANA – JULY 18, 2018

At the risk of stating the obvious: Plastics are an indispensable part of our modern world. Yet, plastic materials cause untold problems for the environment. One of the properties that makes plastics so useful also makes them harmful. Plastics don’t readily degrade.

Recently, researchers discovered a new strain of bacteria that had recently evolved the ability to degrade plastics. These microbes may help solve some of the environmental problems caused by plastics, but their evolution seemingly causes new problems for people who hold the view that a Creator is responsible for life’s origin and design. But, is this really the case? To find out, we need to break down this discovery.

One plastic in widespread use today is polyethylene terephthalate (PET). This polymer was patented in the 1940s and became widely used in the 1970s. Most people are familiar with PET because it is used to make drinking bottles.

This material is produced by reacting ethylene glycol with terephthalic acid (both produced from petroleum). Crystalline in nature, this plastic is a durable material that is difficult to break down, because of the inaccessibility of the ester linkages that form between the terephthalic acid and ethylene glycol subunits that make up the polymer backbone.

PET can be recycled, thereby mitigating its harmful effects on the environment. A significant portion of PET is mechanically recycled by converting it into fibers used to manufacture carpets.

In principle, PET could be recycled by chemically breaking the ester linkages holding the polymer together. When the ester linkages are cleaved, ethylene glycol and terephthalic acid are the breakdown products. These recovered starting materials could be reused to make more PET. Unfortunately, chemical recycling of PET is expensive and difficult to carry out because of the inaccessibility of the ester linkages. In fact, it is cheaper to produce PET from petroleum products than from the recycled monomers.

Can Bacteria Recycle PET?

An interesting advance took place in 2016 that has important implications for PET recycling. A team of Japanese researchers discovered a strain of the bacterium Ideonella sakaiensis that could break down PET into terephthalic acid and ethylene glycol.1 This strain was discovered by screening wastewater, soil, sediments, and sludge from a PET recycling facility. The microbe produces two enzymes, dubbed PETase and MHETase, that work in tandem to convert PET into its constituent monomers.

Evolution in Action

Researchers think that this microbe acquired DNA from the environment or another microbe via horizontal gene transfer. Presumably, this DNA fragment harbored the genes for cutinase, an enzyme that breaks down ester linkages. Once the I. sakaiensis strain picked up the DNA and incorporated it into its genome, the cutinase gene must have evolved so that it now encodes the information to produce two enzymes with the capacity to break down PET. Plus, this new capability must have evolved rather quickly, over the span of a few decades.

PETase Structure and Evolution

In an attempt to understand how PETase and MHETase evolved and how these two enzymes might be engineered for recycling and bioremediation purposes, a team of investigators from the University of Plymouth determined the structure of PETase with atomic level detail.2 They learned that this enzyme has the structural components characteristic of a family of enzymes called alpha/beta hydrolases. Based on the amino acid sequence of the PETase, the researchers concluded that its closest match to any existing enzyme is to a cutinase produced by the bacterium Thermobifida fusca. One of the most significant differences between these two enzymes is found at their active sites. (The active site is the location on the enzyme surface that binds the compounds that the enzyme chemically alters.) The active site of the PETase is broader than the T. fusca cutinase, allowing it to accommodate PET polymers.

As researchers sought to understand how PETase evolved from cutinase, they engineered amino acid changes in PETase, hoping to revert it to a cutinase. To their surprise, the resulting enzyme was even more effective at degrading PET than the PETase found in nature.

This insight does not help explain the evolutionary origin of PETase, but the serendipitous discovery does point the way to using engineered PETases for recycling and bioremediation. One could envision spraying this enzyme (or the bacterium I. sakaiensis) onto a landfill or in patches of plastics floating in the Earth’s oceans. Or alternatively using this enzyme at recycling facilities to generate the PET monomers.

As a Christian, I find this discovery exciting. Advances such as these will help us do a better job as planetary caretakers and as stewards of God’s creation, in accord with the mandate given to us in Genesis 1.

But, this discovery does raise a question: Does the evolution of a PET-eating bacterium prove that evolution is true? Does this discovery undermine the case for creation? After all, it is evolution happening right before our eyes.

Is Evolution in Action Evidence for Evolution?

To answer this question, we need to recognize that the term “evolution” can take on a variety of meanings. Each one reflects a different type of biological transformation (or presumed transformation).

It is true that organisms can change as their environment changes. This occurs through mutations to the genetic material. In rare circumstances, these mutations can create new biochemical and biological traits, such as the ones that produced the strain of I. sakaiensis that can degrade PET. If these new traits help the organism survive, it will reproduce more effectively than organisms lacking the trait. Over time, this new trait will take hold in the population, causing a transformation of the species.

And this is precisely what happened with I. sakaiensis. However, microbial evolution is not controversial. Most creationists and intelligent design proponents acknowledge evolution at this scale. In a sense, it is not surprising that single-celled microbes can evolve, given their extremely large population sizes and capacity to take up large pieces of DNA from their surroundings and incorporate it into their genomes.

Yet, I. sakaiensis is still I. sakaiensis. In fact, the similarity between PETase and cutinases indicates that only a few amino acid changes can explain the evolutionary origin of new enzymes. Along these lines, it is important to note that both cutinase and PETase cleave ester linkages. The difference between these two enzymes involves subtle structural differences triggered by altering a few amino acids. In other words, the evolution of a PET-degrading bacterium is easy to accomplish through a form of biochemical microevolution.

But just because microbes can undergo limited evolution at a biochemical level does not mean that evolutionary mechanisms can account for the origin of biochemical systems and the origin of life. That is an unwarranted leap. This study is evidence for microbial evolution, nothing more.

Though this advance can help us in our planetary stewardship role, this study does not provide the type of evidence needed to explain the origin of biochemistry and, hence, the origin of life through evolutionary means. Nor does it provide the type of evidence needed to explain the evolutionary origin of life’s major groups. Evolutionary biologists must develop appropriate evidence for these putative transformations, and so far, they haven’t.

Evidence of microbial evolution in action is not evidence for the evolutionary paradigm.

Resources:

Endnotes

  1. Shosuke Yoshida et al., “A Bacterium that Degrades and Assimilates Poly(ethylene terephthalate)” Science 351 (March 11, 2016): 1196–99, doi:10.1126/science.aad6359.
  2. Harry P. Austin, et al., “Characterization and Engineering of a Plastic-Degrading Aromatic Polyesterase,” Proceedings of the National Academy of Sciences, USA (April 17, 2018): preprint, doi:10.1073/pnas.1718804115.
Reprinted with permission by the author
Original article at:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2018/07/18/do-plastic-eating-bacteria-dump-the-case-for-creation

Did Neanderthals Self-Medicate?

neanderthalselfmedicate

BY FAZALE RANA – JANUARY 24, 2018

Calculus is hard.

But it is worth studying because it is such a powerful tool.

Oh, wait!

You don’t think I’m referring to math, do you? I’m not. I’m referring to dental calculus, the hardened plaque that forms on teeth.

Recently, researchers from Australia and the UK studied the calculus scraped from the teeth of Neanderthals and compared it to the calculus taken from the teeth of modern humans and chimpanzees (captured from the wild) with the hope of understanding the diets and behaviors of these hominins.1 The researchers concluded that this study supports the view that Neanderthals had advanced cognitive abilities like that of modern humans. If so, this conclusion creates questions and concerns about the credibility of the biblical view of humanity; specifically, the idea that we stand apart from all other creatures on Earth because we are uniquely made in God’s image. Ironically, careful assessment of this work actually supports the notion of human exceptionalism, and with it provides scientific evidence that human beings are made in God’s image.

This study built upon previous work in which researchers discovered that they could extract trace amounts of different types of compounds from the dental calculus of Neanderthals and garner insights about their dietary practices.2 Scientists have learned that when plaque forms, it traps food particles and microbes from the mouth and respiratory tract. In the most recent study, Australian and British scientists extracted ancient DNA from the plaque samples isolated from the teeth of Neanderthals recovered in Spy Cave (Belgium) and El Sidrón (Spain). These specimens age-date between 42,000 and 50,000 years in age. By sequencing the ancient DNA in the samples and comparing the sequences to known sequences in databases, the research team determined the types of food Neanderthals ate and the microorganisms that infected their mouths.

Neanderthal Diets

Based on the ancient DNA recovered from the calcified dental plaque, the researchers concluded that the Neanderthals unearthed at Spy Cave and El Sidrón consumed different diets. The calculus samples taken from the Spy Cave specimens harbored DNA from the woolly rhinoceros and European wild sheep. It also contained mushroom DNA. On the other hand, the ancient DNA samples taken from the dental plaque of the El Sidrón specimens came from pine nuts, moss, mushrooms, and tree bark. These results suggest that the Spy Neanderthals consumed a diet comprised largely of meat, while the El Sidrón hominins ate a vegetarian diet.

The microbial DNA recovered from the dental calculus confirmed the dietary differences between the two Neanderthal groups. In Neanderthals, and in modern humans, the composition of the microbiota in the mouth is dictated in part by the diet, varying in predictable ways for meat-based and plant-based diets, respectively.

Did Neanderthals Consume Medicinal Plants?

One of the Neanderthals from El Sidrón—a teenage boy—had a large dental abscess. The researchers recovered DNA from his dental calculus showing that he also suffered from a gut parasite that causes diarrhea. But, instead of suffering without any relief, it looks as if this sick individual was consuming plants with medicinal properties. Researchers recovered DNA from poplar plants, which produce salicylic acid, a painkiller, and DNA from a fungus that produces penicillin, an antibiotic. Interestingly, the other El Sidrón specimen showed no evidence of ancient DNA from poplar or the fungus, Penicillium.

If Neanderthals were able to self-medicate, the researchers conclude that these hominins must have had advanced cognitive abilities, similar to those of modern humans. One of the members of the research team, Alan Cooper, muses, “Apparently, Neandertals possessed a good knowledge of medicinal plants and their various anti-inflammatory and pain-relieving properties, and seem to be self-medicating. The use of antibiotics would be very surprising, as this is more than 40,000 years before we developed penicillin. Certainly, our findings contrast markedly with the rather simplistic view of our ancient relatives in popular imagination.”3

Though intriguing, one could argue that the research team’s conclusion about Neanderthals self-medicating is a bit of an overreach, particularly the idea that Neanderthals were consuming a specific fungus as a source of antibiotics. Given that the El Sidrón Neanderthals were eating a vegetarian diet, it isn’t surprising that they occasionally consumed fungus because Penicillium grows naturally on plant material when it becomes moldy. This conclusion is based on a single Neanderthal specimen; thus, it could simply be a coincidence that the sick Neanderthal teenager consumed the fungus. In fact, it would be virtually impossible for Neanderthals to intentionally eat penicillin-producing fungi because, according to anthropologist Hannah O’Regan from the University of Nottingham, “It’s difficult to tell these specific moulds apart unless you have a hand lens.”4

Zoopharmacognosy

But even if Neanderthals were self-medicating, this behavior is not as remarkable as it might initially seem. Many animals self-medicate. In fact, this phenomenon is called zoopharmacognosy.5 For example, chimpanzees will consume the leaves of certain plants to make themselves vomit, in order to rid themselves of intestinal parasites. So, instead of viewing the consumption of poplar plants and fungus by Neanderthals as evidence for advanced behavior, perhaps, it would be better to regard it as one more instance of zoopharmacognosy.

Medicine and Human Exceptionalism

The difference between the development and use of medicine by modern humans and the use of medicinal plants by Neanderthals (assuming they did employ plants for medicinal purposes) is staggering. Neanderthals existed on Earth longer than modern humans have. And at the point of their extinction, the best that these creatures could do is incorporate into their diets a few plants that produced compounds that were natural painkillers or antibiotics. On the other hand, though on Earth for only around 150,000 years, modern humans have created an industrial-pharmaceutical complex that routinely develops and dispenses medicines based on a detailed understanding of chemistry and biology.

As paleoanthropologist Ian Tattersall and linguist Noam Chomsky (along with other collaborators) put it:

“Our species was born in a technologically archaic context . . . . Then, within a remarkably short space of time, art was invented, cities were born, and people had reached the moon.”6

And biomedical advance has yielded an unimaginably large number of drugs that improve the quality of our lives. In other words, comparing the trajectories of Neanderthal and modern human technologies highlights profound differences between us—differences that affirm modern humans really are exceptional, echoing the biblical view that human beings are truly made in God’s image.

Resources

Endnotes

  1. Laura S. Weyrich et al., “Neanderthal Behavior, Diet, and Disease Inferred from Ancient DNA in Dental Calculus,” Nature 544 (April 20, 2017): 357–61, doi:10.1038/nature21674.
  2. Karen Hardy et al., “Neanderthal Medics? Evidence for Food, Cooking, and Medicinal Plants Entrapped in Dental Calculus,” Naturwissenschaften 99 (August 2012): 617–26, doi:10.1007/s00114-012-0942-0.
  3. “Dental Plaque DNA Shows Neandertals Used ‘Aspirin,’” Phys.org, updated March 8, 2017, https://phys.org/print408199421.html.
  4. Colin Barras, “Neanderthals May Have Medicated with Penicillin and Painkillers,” New Scientist, March 8, 2017, https://www.newscientist.com/article/2123669-neanderthals-may-have-medicated-with-penicillin-and-painkillers/.
  5. Shrivastava Rounak et al, “Zoopharmacognosy (Animal Self Medication): A Review,” International Journal of Research in Ayurveda and Pharmacy 2 (2011): 1510–12.
  6. Johan J. Bolhuis et al., “How Could Language Have Evolved?,” PLoS Biology 12 (August 26, 2014): e1001934, doi:10.1371/journal.pbio.1001934.
Reprinted with permission by the author
Original Article:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2018/01/24/did-neanderthals-self-medicate

What Does the Discovery of Earth’s Oldest Fossils Mean for Evolutionary Models?

whatdoesdiscoveryofearths

BY FAZALE RANA – MARCH 29, 2017

Communication can be a complex undertaking. Often, people don’t say what they really mean. And if they do, their meaning is often veiled in what they say. That’s why it’s important to learn how to read between the lines. Understanding the real meaning when something isn’t explicitly stated usually requires experience and some insider’s knowledge.

Thanks to my expertise in biochemistry and origin-of-life research and 20 years of experience as a Christian apologist, I can usually read between the lines when scientists respond to discoveries that challenge the evolutionary paradigm, such as the recently reported discovery of Earth’s oldest fossils. Because of their fear that intelligent design proponents and creationists will make use of these types of discoveries to advance the case for a Creator, scientists can be adept at masking their concern when they discuss the implications of these discoveries. But if you know how to read between the lines, their consternation is as plain as day.

Earth’s Oldest Fossils

An international team made up of scientists from the United Kingdom, United States, Canada, and Australia recently reported on the discovery of microfossils from a geological formation in the northern part of Quebec, Canada.1 Formed from ancient hydrothermal vents, this iron-rich geological system dates somewhere between 3.77 and 4.3 billion years in age.

The putative microfossils consist of microscopic hematite filaments and tubes, like those found in modern hydrothermal vents. Today, iron-oxidizing microbes produce hematite filaments and tubes when sheaths of extracellular materials become coated by iron oxyhydroxide. Added evidence for the biogenicity of these microfossils comes from carbonate and apatite associated with the hematite structures. These compounds can also be produced as by-products of the metabolic activity of microorganisms. The research team also discovered graphite inclusions enriched in carbon-12, a geochemical signature of life. Finally, the Raman spectrum of the carbonaceous deposits display features that also point to the biological origin of this material.

Matthew Dodd, one of the research team members, argues that “we can think of alternative explanations for each of these singular observations, but why all of these features occur together can really only be explained by one thing, which is a biological interpretation.”2

The discovery of these microfossils comes on the heels of the discovery of stromatolites in newly exposed rock outcroppings in Greenland, dating at 3.7 billion years.3 Both recent discoveries corroborate earlier work that yielded several different geochemical markers for biological activity. In short, an impressive weight of evidence points to the early appearance of complex and diverse microbial life on Earth.

Skepticism about Bioauthenticity

Despite this impressive collection of evidence, several scientists have expressed skepticism about the bioauthenticity of the fossils. Journalist Sarah Kaplan explains why: “Findings like these are subject to intense scrutiny because they have potentially far-reaching implications for the study of early organisms on Earth and other planets.”4

As I have discussed previously when the discovery of 3.7-billion-year-old stromatolite fossils were unearthed in Greenland, one of the implications of the early appearance of metabolically complex and diverse microbial life on Earth is that it calls into question evolutionary explanations for the origin of life. These discoveries indicate that life appeared suddenly on Earth, in a geological instant. Yet traditionally, origin-of-life researchers maintained that life’s origin via chemical evolution would have required hundreds of millions of years, perhaps even a billion years.

This concern can be read between the lines in the objections raised by scientists responding to this discovery.

Some argue that the research team hasn’t amassed enough evidence to convince them of the biogenicity of the fossils, pointing out that extraordinary claims require extraordinary evidence. But the claim that life appeared early in Earth’s history is only extraordinary within the evolutionary paradigm. To view these microfossils as extraordinary highlights the trouble these fossil finds cause for an evolutionary approach to the origin-of-life question.

Others argue that iron-oxidizing microbes are too complex to have appeared this early in Earth’s history. Some assert that the rock layers containing the fossils are much younger than 3.77 billion years, raising concerns about the dating methods used to determine the age of the rocks harboring the microfossils. Again, both complaints reveal concerns about the impact that this fossil find has on the evolutionary explanation for life’s beginning. The hope is that by forcing the fossils to appear much later in Earth’s history, scientists can explain the metabolic complexity of the organisms that produced the hematite deposits by giving evolutionary processes more time. Yet there is no reason to dispute the dates for the rock formations in northern Canada, and the case for the biogenicity of the fossils is strong.

Some dismiss the bioauthenticity of the microfossils because it would require life to originate under hostile conditions, caused by the late heavy bombardment. These hostile conditions would have frustrated the origin-of-life process, potentially sterilizing Earth, making it difficult to imagine how life could have emerged, let alone diversified, at 3.77 billion years ago—at least from an evolutionary vantage point. If these fossils aren’t authentic, then scientists don’t have to confront the counterintuitive fact that life appeared under hostile conditions.

It seems to me that these scientists are dangerously close to evaluating the validity of the 3.77-billion-year-old microfossils based on how well they fit into the evolutionary paradigm, instead of evaluating evolutionary explanations for the origin of life based on the fossil evidence—a complete reversal of the way that the scientific method is supposed to work.

Nevertheless, a quick read between the lines reveals just how awkwardly this fossil find fits within the evolutionary paradigm.

Implications for Creation Models

Though the discovery of 3.77-billion-year-old microfossils confounds evolutionary origin-of-life models, it affirms RTB’s origin-of-life model. As described in Origins of Life, two key predictions of this model include (1) life appearing on Earth soon after the planet’s formation and (2) first life possessing intrinsic complexity. And these predictions are satisfied by this latest advance.

The writing is on the wall: the case for a Creator’s role in the origin of life is becoming more and more evident.

Resources

Endnotes

  1. Matthew S. Dodd et al., Evidence for Early Life in Earth’s Oldest Hydrothermal Vent Precipitates,”Nature 543 (March 2017): 60–64, doi:10.1038/nature21377.
  2. Sarah Kaplan, “Newfound 3.77-Billion-Year-Old Fossils Could Be Earliest Evidence of Life on Earth,” Washington Post, March 1, 2017, https://www.washingtonpost.com/news/speaking-of-science/wp/2017/03/01/newfound-3-77-billion-year-old-fossils-could-be-earliest-evidence-of-life-on-earth.
  3. Allen P. Nutman et al., “Rapid Emergence of Life Shown by Discovery of 3,700-Million-Year-Old Microbial Structures,” Nature 537 (September 2016): 535–38, doi:10.1038/nature19355.
  4. Kaplan, “Newfound 3.77-Billion-Year-Old Fossils.”
Reprinted with permission by the author
Original article at:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2017/03/29/what-does-the-discovery-of-earth-s-oldest-fossils-mean-for-evolutionary-models