Reasons to Believe

Does Dinosaur Tissue Challenge Evolutionary Timescales? A Response to Kevin Anderson, Part 2

What is the proper relationship between science and the Christian faith? Answering that question can be complicated, involving an interplay between science, philosophy, theology, and biblical studies. Perhaps it’s not surprising that evangelical Christians (who take Scripture seriously) advocate disparate models, weighing differently the data and insights from science and Scripture.

The three most prominent views held by evangelical Christians are young-earth creationism (YEC), old-earth creationism (OEC), and evolutionary creationism (EC). Each view has strengths and weaknesses. And each view accepts and rejects (or at least expresses skepticism about) certain aspects of current scientific paradigms.

It goes without saying that “in-house” discussions among adherents of these three models can become quite contentious, and for good reason—much is at stake. No one wants to undermine Scripture. And no one wants to recklessly disregard scientifically established ideas. To do so could compromise the Church’s ability to reach out to non-Christians. In my view, it is okay to question scientific dogma—particularly if it challenges key tenets of the Christian faith. But it is important to do so responsibly and in a scientifically credible way.

My chief motivation for writing Dinosaur Blood and the Age of the Earth was to prevent well-intentioned Christians from unwittingly undercutting their effectiveness when sharing their faith by using a seemingly compelling scientific argument for a young Earth (with the hope of demonstrating the credibility of the creation accounts from a young-earth vantage point).

Many Christians regard the discovery of soft-tissue remnants, associated with fossilized remains age-dated to be upwards of hundreds of millions of years, as compelling scientific evidence for a young Earth. And I can see why.

Soft tissues shouldn’t survive for millions of years. Based on common wisdom, these materials should readily degrade in a few thousand years. That being the case, the discovery of soft-tissue remnants associated with fossils is a compelling reason to question the reliability of radiometric dating methods used to determine the age of these fossils, and along with it, Earth’s antiquity. And YECs argue that these discoveries provide powerful scientific evidence for a young Earth and support the idea that the fossil record results from a recent global (worldwide) flood.

Yet few scientifically minded people are swayed by this argument. In Dinosaur Blood and the Age of the Earth, I explain why this increasingly prominent argument for a young Earth is invalid. First, I explain why radiometric dating methods are reliable. Secondly, I explain how it is scientifically conceivable that soft-tissue remnants could survive for upwards of hundreds of millions of years.

When I published Dinosaur Blood and the Age of the Earth, I expected responses from YECs. And there have been a few. Generally, I won’t engage in tit for tat when my ideas are criticized. But I am making an exception in the case of Kevin Anderson’s recent technically rigorous article for Answers in Depth, the journal of Answers in Genesis, titled “Dinosaur Tissue: A Biochemical Challenge to the Evolutionary Timescale.”  Because Anderson is a scholar, and because his approach is fair-minded, it is important to pay attention to his critiques of my work and to engage his ideas.

In part 1 (of this two-part blog series), I addressed Anderson’s dismissal of the biomolecular durability argument that I present in Dinosaur Blood and the Age of the Earth as part of the explanation for collagen (and keratin) survivability in fossils. In this second part, I engage Anderson’s challenges to what he refers to as “the most popular explanation for prolonged preservation” of soft tissue—namely, the “iron model.”1

The Iron Model for Soft-Tissue Preservation

As described in Dinosaur Blood and the Age of the Earth, paleontologists have noted iron deposits associated with preserved soft-tissue remnants in a number of fossilized specimens. (In fact, iron deposits were associated with the recently discovered dinosaur feathers preserved in amber, age-dated to 99 million years.)2 On this basis, they speculate that the iron, in conjunction with oxygen, helps to preserve soft-tissue materials through a variety of possible mechanisms, including killing off microbes, inhibiting enzymes, and causing cross-linking reactions that function as a fixative (like formaldehyde), at least until mineral entombment takes place.3 The researchers posit that iron associated with hemoglobin (the protein that binds and carries oxygen found in red blood cells) is the primary source of iron. Presumably, when the organism dies, the red blood cells lyse, releasing hemoglobin and iron into the tissue.

To demonstrate the validity of this idea, researchers from North Carolina State University dispersed ostrich blood vessels in an aqueous solution of ruptured blood cells. They observed iron deposits forming on the blood vessels. The blood cell lysate stabilized the soft tissue. Compared to blood vessels dispersed in water (in the presence and absence of oxygen), which lasted only a few days, blood vessels exposed to red blood lysates persisted for upwards of two years (and counting).

Yet, Anderson questions the iron model for a variety of reasons:

  • He raises doubts about the relevancy of the laboratory experiments on the ostrich blood vessels.
  • He expresses concern that the iron level in dinosaurs is insufficient for it to achieve adequate preservation, even if the iron model is valid.
  • He notes that the reactions that promote cross-linking also destroy amino acids (even though amino acids have been recovered from dinosaur and bird fossils).

In my view, none of these criticisms bears much weight.

To be fair, Anderson rightly highlights a problem constantly confronting scientists studying the origin and history of life—namely, how do chemical and physical processes identified in the laboratory under highly controlled conditions (and the auspices of researchers) translate to the uncontrolled conditions of Earth’s past environment? Though granting Anderson this point—in fact, I have raised a similar criticism toward work in prebiotic chemistry in my book Creating Life in the Lab—it is important to acknowledge that the stability experiments with ostrich blood vessels demonstrate that, in principle, the iron model has merit. It is also worth noting that the conditions employed by the researchers in the lab experiments represent a worst-case scenario because the vessels were dispersed in water, which promotes hydrolysis and microbial growth. In other words, under “real-life” conditions, iron-mediated preservation of soft tissue has an even greater likelihood than in the experiments conducted in the laboratory.

Concerning Anderson’s second point about iron abundances in dinosaurs (or ancient birds), it is noteworthy that iron from the lysed red blood cells binds to the ostrich blood vessels, suggesting some type of concentrating mechanism that localizes the iron to the soft tissue. Also, as Anderson acknowledges, there may be environmental sources of iron that could contribute to the iron pool. Even if there are still questions as to the source and available levels of iron for tissue preservation, this mechanism appears to be significant. As already noted, paleontologists have discovered iron associated with soft-tissue remnants found in fossils.

As for Anderson’s third point, it is true that the reaction mediated by iron and oxygen (which drives cross-linking) alters amino acids. And it is true that unaltered amino acids are found in the fossil specimens. But these two results are not mutually exclusive. How is that possible? It is because chemical reactions don’t necessarily go to completion. To put it another way, during the preservation process, it is unlikely that all the amino acids composing dinosaur proteins reacted via the iron- and oxygen-mediated reactions. Some of the amino acids will remain unaltered—even highly reactive ones. It is noteworthy that the molecular profiles of materials extracted from dinosaur fossils show a relative dearth of less stable amino acids and an abundance of more durable amino acids, exactly as expected if the amino acids come from the remnants of ancient protein specimens.4

Ultimately, my complaint about Anderson’s critiques has less to do with his scientific points and more to do with his “either-or” posture. Even if Anderson’s critique of the iron model stands, it doesn’t mean that there is no way to account for soft-tissue preservation. As I argue in Dinosaur Blood and the Age of the Earth, there is probably no single preservation mechanism that accounts for the survival of soft-tissue materials. In reality, it is a combination of mechanisms working additively (maybe synergistically) that accounts for the persistence of soft tissue in fossils, with the iron-oxygen mechanism working in conjunction with other processes.

Other Preservation Mechanisms

In Dinosaur Blood and the Age of the Earth, I argue that many of the mechanisms that affect soft-tissue decomposition (hydrolysis via exposure to water, oxidation caused by oxygen exposure, breakdown by environmental enzymes, and microbial decomposition) can actually protect soft-tissue remnants under some circumstances.

In response to this point, Anderson argues that these claims are “self-contradictory.”5 But this is exactly my point. Conditions traditionally thought to drive soft-tissue breakdown preserve soft tissues under certain sets of conditions. In other words, traditional views about soft-tissue decomposition aren’t likely correct.

In fact, the iron model illustrates this point. In keeping with common wisdom, exposure to oxygen drives soft-tissue destruction. Conversely, excluding oxygen during the fossilization process should aid in preservation by preventing oxidative decomposition of the soft-tissue materials. But oxidation reactions also drive the cross-linking of proteins. So, exposure to oxygen also preserves soft tissues. Whether decomposition or preservation occurs depends on the specific circumstances surrounding the fossilization process, with some conditions “tipping the scale” in favor of decomposition and other conditions “moving the needle” toward preservation. And, of course, iron released from hemoglobin (or from environmental sources) accelerates the cross-linking reactions, helping to stabilize the soft-tissue materials.

Are Fossils Thousands of Years Old or Millions of Years Old?

Anderson concludes his argument by lamenting the bias of the scientific community. He says: “The problem is that the evolutionary community does not really consider the first alternative [dinosaurs aren’t as old as we think they are] as a possibility. Thus, it really is not an ‘either/or’ option. In their view the fossils must be old, therefore the tissue must somehow have survived (biochemical contradictions not withstanding). . . . No one has ever observed multi-millions of years of animal tissue preservation. The only reason there is even a quest for an unknown preservation mechanism is because evolutionary assumptions require dinosaur fossils to be at least 65 million years old.”6

Anderson’s protests not withstanding, the scientific community does not assume the fossils to be millions of years old but has measured fossils to be millions of years old using sound, scientifically established radiometric methods. Consequently, the scientific community has observed soft tissue preserved for millions of years, with the recovery of blood-vessel remnants and protein fragments from the fossils of dinosaurs (and other organisms).

Finally, while it is true that the scientific community lacks full understanding of the mechanisms involved, preservation of soft tissues in fossils does not stand as a “biochemical contradiction.” Instead, there are sound explanations for the persistence of soft-tissue remnants in fossils. And as work continues, I predict that the scientific community will identify new preservation mechanisms. In fact, this has already happened. Researchers now think that eumelanin released from melanosomes can serve as a fixative, assisting in the preservation of keratin associated with fossilized feathers, claws, and skin.7

I appreciate Kevin Anderson’s thoughtful engagement with my ideas regarding soft-tissue preservation, but I disagree with his conclusions. Simply put, soft-tissue preservation in fossils is not a valid scientific argument for a young Earth, nor does it provide evidence that the fossil record was laid down as a result of a recent, global flood.

Resources

Endnotes

  1. Kevin Anderson, “Dinosaur Tissue: A Biochemical Challenge to the Evolutionary Timescale,” Answers in Depth, October 20, 2016, http://answersingenesis.org/fossils/dinosaur-tissue.
  2. Lida Xing et al., “A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber,” Current Biology 26 (December 2016): 3352–60, doi:10.1016/j.cub.2016.10.008.
  3. Mary Schweitzer et al., “A Role for Iron and Oxygen Chemistry in Preserving Soft Tissues, Cells and Molecules from Deep Time,” Proceedings of the Royal Society B 281 (January 2014): 20132741, doi:10.1098/rspb.2013.2741.
  4. Mary Schweitzer et al., “Preservation of Biomolecules in Cancellous Bone of Tyrannosaurus Rex,” Journal of Vertebrate Paleontology 17 (June 1997): 34959, doi:10.1080/02724634.1997.10010979.
  5. Kevin Anderson, “Dinosaur Tissue.”
  6. Ibid.
  7. Alison Moyer, Wenxia Zheng, and Mary Schweitzer, “Keratin Durability Has Implications for the Fossil Record: Results from a 10 Year Feather Degradation Experiment,” PLoS One 11 (July 2016): e0157699, doi:10.1371/journal.pone.0157699.

Subjects: Age of the Earth, Fossil Record, Dinosaurs, Flood Geology