Can Keratin in Feathers Survive for Millions of Years?
I don’t like conflict. In fact, I try to avoid it whenever possible. And that’s part of the reason I never wanted to become directly involved in the young-earth/old-earth controversy that takes place within the church.
Frankly, I find the debate tedious, and a distraction from the real work at hand: helping skeptics and seekers recognize the scientific evidence for God’s existence and Scripture’s reliability.
Of course, if people ask me age-of-the-earth questions, I am quick to explain why I hold to an old-earth/day-age interpretation for Genesis 1 and what I see as biblical, theological, and scientific issues with a young-earth/calendar day interpretation of the Genesis 1 creation account.
Soft Tissues in Fossils and the Age of the Earth
Over the course of the last few years, one question that has come up a lot relates to the discovery of soft tissue remnants in fossils, such as the blood cells and blood vessels remains recovered from a T. rex specimen that age-dates to 68 million years old. Young earth creationists make use of these surprising results to argue that it is impossible for fossils to be millions of years old. They argue that soft tissues shouldn’t survive that long. These materials should readily degrade in a few thousand years. In their view, these finds challenge the reliability of radiometric dating methods used to determine the age of these fossils, and along with it, Earth’s antiquity. Instead, they argue that these breakthrough discoveries provide compelling scientific evidence for a young Earth and support the idea that the fossil record results from a recent global (worldwide) flood.
Because I’m a biochemist—and an old earth creationist—people frequently ask me how I make sense of the T. rex find and the discovery of other types of soft tissue remnants in the fossil remains of other creatures that age-date to several hundred million years, in some cases.
Dinosaur Blood and the Age of the Earth
These queries eventually motivated me to write Dinosaur Blood and the Age of the Earth. And I am glad I did. Aside from the young-earth/old-earth debate, the scientific questions related to soft tissue finds in fossils are captivating.
The central question of Dinosaur Blood and the Age of the Earth centers around soft tissue durability: If radiometric dating is reliable, then how is it possible for soft tissue remnants to persist for millions of years?
Recent work by a research team at North Carolina State University (NC State)—headed up by Mary Schweitzer—helps address this question, specifically focusing on beta-keratin fragments recovered from the fossilized feathers and claws of Shuvuuia deserti and Rahonavis ostromi.1
How Can Keratin Survive in Fossils?
As I discuss in Dinosaur Blood and the Age of the Earth, some biomolecules (such as keratins) form extremely stable structures that delay their degradation. Keratins have a number of structural features (such as extensive crosslinking) that helps explain why fragments of these proteins could survive for tens of millions of years, under the right conditions.2 But my analysis was theoretical. Even though my assessment was based on sound biochemical principles, it would be nice to have some corroborating experimental evidence to support my claims. (The old saying in science applies: “theories guide, experiments decide.”) And that is precisely what the NC State researchers provide in their recent study.
Schweitzer and her team conducted a ten-year experiment to gain insight into the natural degradation processes of feathers (and other biological materials made up of keratins such as skin, claws, beaks, and hair). To do this, they exposed feathers from a Hungarian partridge to a variety of conditions, and then analyzed the samples busing: (1) transmission electron microscopy (TEM) to monitor changes in the fine structure of the feather’s anatomy; and (2) a technique called in situ immunofluorescence to determine if pieces of keratin proteins persisted in the feather remains.
Of particular interest is the feather samples Schweitzer and her team wrapped in aluminum foil and heated in an oven for 10 years at 630°F—conditions used to sterilize glassware. Many paleontologists consider high heat to be a proxy for deep time.
Perhaps it is no surprise, when viewed under a microscope, the macroscopic features of feathers treated at high temperatures were completely lost. Instead the only thing visible were shiny black pieces of “charcoal-like” material. Yet, when examined at high magnification with a TEM, the investigators were able to visualize fragments of feather barbs. Using their immunofluorescence technique, the researchers were able to detect clear evidence of keratin fragments in the sample.
These observations align with my thoughts about keratin’s durability, making it all the more reasonable to think that soft tissue remnants persist in millions-of-years old fossil remains. In fact, when the researchers applied their immunofluorescence to the Shuvuuia deserti samples, once again, they found evidence for keratin fragments in these fossil remains.
As I point out in Dinosaur Blood and the Age of the Earth, molecular durability alone isn’t sufficient to account for soft tissue survivability. For soft tissue remnants to persist in fossil, the rate of fossilization has to outpace the rate of soft tissue degradation. When that happens, a mineral ‘casing’ will entomb the soft tissue before it completely decomposes, preserving it for paleontologists to later discover. In addition to molecular durability, scientists have identified a number of mechanisms that contribute to both the degradation and preservation of soft tissues during the process of burial and fossilization.
Along these lines, the NC State scientists speculate on processes that might extend keratin’s survivability in feathers—at least, long enough for mineral entombment to occur. They think one of their observations about the high-heat sample offers a clue. The research team noted that melanosomes (the organelles that harbor pigments, giving feathers their colors) were absent after heating for ten years at 630°F. On this basis, they conclude that paleontologists have made a mistake when they interpret microbodies as melanosomes in fossilized feathers. Instead, they think that the mirobodies derive from microbes.
This reinterpretation is good news for keratin preservation on two accounts. It is true that microbial activity can destroy soft tissues, but the NC State scientists think it can also help speed up the fossilization process leading to the preservation of keratin remnants. How? Because microbes secrete materials (called exopolymeric substances) that promote deposition of minerals, speeding up the entombment of the soft tissue. Additionally, the NC State researchers think that melanosome degradation may also be important. When these organelles break down, they release their contents (eumelanin) which may function like a fixative, slowing down tissue degradation long enough for the soft tissue to be entombed.
The NC State study has unearthed fascinating details regarding feather decomposition and provides key insights that help account for the persistence of keratin in fossilized remains of reptiles, birds, and feathered dinosaurs that date to tens of millions of years old.
“Structure of Collagen Unravels the Case for a Young Earth” by Fazale Rana (Article)
Dinosaur Blood and the Age of the Earth by Fazale Rana (Book)
- 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.
- Fazale Rana, Dinosaur Blood and the Age of the Earth (Covina, CA: RTB Press, 2016), 57–58.