Is there a bona fide scientific challenge to the age of the Earth, which is measured to be 4.5 billion years old? As an old-earth creationist (OEC), I would answer no. But, there has been one scientific argument for a young Earth that has given me some pause for thought: the discovery of soft tissue remnants in the fossilized remains of dinosaurs (and other organisms). Paleontologists have discovered the remnants of blood vessels, red blood cells, bone cells, and protein fragments, such as collagen and keratin, in the fossilized remains of dinosaurs that age-date older than 65 million years.
These unexpected finds have become central to the case made by young-earth creationists (YEC) for a 6,000-year-old Earth. In effect, the argument goes like this: Soft tissues shouldn’t survive for millions of years. Instead, these materials should readily degrade in a few thousand years. Accordingly, the discovery of soft tissue remnants associated with fossils is a prima facie challenge to the reliability of radiometric dating methods used to determine the age of these fossils, and along with it, Earth’s antiquity. YECs argue that these discoveries provide compelling scientific evidence for a young Earth and support the idea that the fossil record results from a recent global (worldwide) flood.
As I detail in my book Dinosaur Blood and the Age of the Earth, there are good reasons to think that radiometric dating methods are reliable. And, that being the case, then there must be an explanation for soft tissue survival. Despite the claims made by YECs, there are scientific mechanisms that can account for the survival of soft-tissue materials for millions of years, as discussed in Dinosaur Blood and the Age of the Earth.
In response to my book (and other recent challenges) to the soft-tissue argument for a young Earth, YEC Kevin Anderson wrote a piece for Answers in Depth, the journal of Answers in Genesis, titled: “Dinosaur Tissue: A Biochemical Challenge to the Evolutionary Timescale.”
In this technically rigorous piece, Anderson argues that paleontologists now view soft-tissue remnants associated with the fossilized remains of dinosaur (and other organisms) as commonplace. On this point, Anderson and I would agree. However, Anderson complains that the scientific community ignores the troubling implications of the soft-tissue finds. He states: “Despite a large body of evidence for the authenticity of the tissue, there remains a pattern of denial within the evolutionist community—presumably to downplay the ramifications of this discovery. . . . Apparently many find the soft-tissue evidence much easier to dismiss than to understand and explain. Perhaps this should not be too surprising. The tissue is certainly difficult to account for within the popular geologic timescale.”1
Yet, in Dinosaur Blood and the Age of the Earth, I explain how soft-tissue remnants associated with fossils are accounted for within “the popular geologic timescale.”
Soft-Tissue Survival in Fossils
Once entombed within a mineral “encasement” (which occurs as the result of the fossilization process), soft-tissue remnants can survive for vast periods of time. The key: the soft tissues must be preserved until entombment happens. In Dinosaur Blood and the Age of the Earth, I identify several factors that promote soft-tissue preservation during the fossilization process. One relates to the structure of the molecules comprising the soft tissues. Some molecules are much more durable than others, making them much more likely to survive until entombment.
This durability partially explains the chemical profile of the compounds associated with soft-tissue remnants. For example, paleontologists have uncovered collagen and keratin fragments associated with dinosaur fossils. These finds make sense because these molecules are heavily cross-linked. And they occur at high levels in bones (collagen) and feathers, skin, and claws (keratin). Researchers also believe that iron released from hemoglobin, and eumelanin released from melanosomes associated with feathers, function as fixatives to further stabilize these molecules, delaying their decomposition.
But What about Measured Collagen Decomposition Rates?
Kevin Anderson agrees that some molecules, such as collagen, resist rapid degradation. However, he rejects the durability argument I present in Dinosaur Blood and the Age of the Earth as part of the explanation for collagen (and keratin) survivability, citing work published in 2011 by researchers from the University of Manchester in the UK.2
In this study, investigators monitored collagen loss in cattle and human bones at 90 °C (194 °F). Even though this high temperature doesn’t directly apply to the fossilization process, the researchers employed a temperature close to the boiling point of water to gather rate data in a reasonable time frame. Still, it took them about one month to generate the necessary data, even at this high temperature. In turn, they used this data to calculate the bone loss at 10 °C (50 °F), which corresponds to the average temperature of a typical archaeological site in a country such as Great Britain. These calculations made use of the Arrhenius rate equation. This equation allows scientists to calculate the rate for a chemical process (such as the breakdown of collagen) at any temperature, once the rate has been experimentally determined for a single temperature. The only assumption is that the physical and chemical properties of the system (in this case, collagen) are the same as the temperature used to measure the reaction rate and the temperature used to calculate the reaction rate.
But, as I discuss in Dinosaur Blood and the Age of the Earth, if the conditions differ, then a phenomenon known as an Arrhenius plot break occurs. This discontinuity makes it impossible to calculate the reaction rate.
On this basis, I questioned if the data generated by the University of Manchester scientists for collagen breakdown in bone near the boiling point of water is relevant to breakdown rates for temperatures that would be under 100 °F, let alone to temperatures near 50 °F. I speculated that at such high temperatures, the collagen would undergo structural changes (for example, breaking of inter-chain hydrogen bonds that cross-link collagen chains together) making this biomolecule much more susceptible to chemical degradation than at lower temperatures where collagen would remain in its native state. In other words, the conditions employed by the research team from the University of Manchester may not be relevant to collagen preservation in fossil remains.
Kevin Anderson challenged my claim, stating, “Dr. Rana speculates that high temperatures may unexpectedly alter how collagen will degrade, so perhaps the Arrhenius equation cannot be properly applied. However, he fails to offer any experimental support for his conclusion. If he wants to challenge these decay studies, he needs to provide experimental evidence that collagen decay is somehow an exception to this equation.”3
Fair enough. Yet, it was relatively easy for me to find the experimental data he requires. A quick literature search produced work published in the early 1970s by a team of researchers from the USDA in Beltsville, MD describing the thermal denaturation profiles of intact collagen from a variety of animal sources.4 The onset temperatures for the denaturation process typically begin near 60 °C (140 °F), reach the mid-point of the denaturation around 70 °C (158 °F), and end around 80 °C (176 °F). In other words, collagen denaturation occurs at temperatures well below the temperatures used by the University of Manchester scientists in their study.
From the denaturation profiles, these researchers determined that the loss of native structure primarily entails the unraveling of the collagen triple helix. This unraveling would expose the protein backbone, making it much easier to undergo chemical degradation.
In Dinosaur Blood and the Age of the Earth, I discuss another reason why the study results obtained by the University of Manchester scientists don’t contradict the recovery of collagen from 70–80 million-year-old dinosaur remains. In effect, this research team was addressing a different question. Namely, how long can collagen last in animal remains in a form that can be isolated and used as a source of genetic information about the organisms found at archaeological and fossil sites?
In other words, they weren’t interested in how long chemically and physically altered collagen fragments would persist in fossil remains, but, instead, how long collagen will retain a useful form that can yield insight into the natural history of past organisms. Specifically, they were interested in the survival of “the non-helical collagen telopeptides located at the very ends of each chain and recently considered potentially useful for species identification in archaeological tissues.”5
The researchers lament that this region of the collagen molecules is “lost to the burial environment within a relatively short period of geologic time.”6 As they point out, the parts of the collagen molecule most useful to characterize the natural history of past organisms and their relationships to extant creatures, unfortunately, are “regions of the protein that do not benefit from as many interchain hydrogen bonds as the helical region, and thus will likely be the first to degrade.”7
The researchers also point out that they expect collagen to persist for much longer than 700,000 years, but in a chemically altered state due to cross-linking reactions and other types of chemical modifications. They state, “Collagen could plausibly be detected at lower concentrations [than 1 percent of the original amounts] in much older material but likely in a diagenetically-altered state and at levels whereby separation from endogenous and exogenous contaminations is much more time-consuming, costly and perhaps applicable only to atypically large taxa that can offer sufficient fossil material for destructive analysis.”8
In other words, chemically altered forms of collagen will persist in animal remains well beyond a million years, particularly if they are large creatures such as dinosaurs. And this is precisely what paleontologists have discovered associated with dinosaur fossils—fragments of diagentically altered collagen (and keratin).
But What about Molecular Fragments Derived from Non-Durable Proteins Isolated from Dinosaur Remains?
Another related challenge raised by Anderson relates to the recovery of molecular fragments of other proteins from dinosaur fossils that are much less durable than collagen. Anderson writes: “Several of these proteins (e.g., myosin, actin, and tropomyosin) are not nearly as structurally ‘tough’ as collagen. . . . Even if there were a biochemical basis that enabled collagen fragments to survive millions of years, this cannot be said about all these other dinosaur proteins.”9
As I point out in Dinosaur Blood and the Age of the Earth, in addition to molecular durability, there are several other factors that contribute to soft-tissue preservation. One relates to abundance. Biomolecules that occur at high levels in soft tissue will be more likely to leave behind traces in fossilized remains than molecules that occur at relatively low levels.
Along these lines, collagen and keratin would have been some of the most abundant proteins in dinosaurs and ancient birds, making up connective tissue and feathers, skin, and claws, respectively. Likewise, actin, myosin, and tropomyosin would also have occurred at high levels in dinosaurs and ancient birds, because these proteins are the major components of muscle. So even though these proteins aren’t as durable as collagen or keratin, it still makes sense that fragments of these biomolecules would be associated with dinosaur fossils because of their abundances.
In short, the durability and abundances of proteins provide a credible explanation for the occurrence of soft-tissue remnants in the fossilized remains of dinosaurs. But these two features don’t fully account for soft-tissue preservation. As it turns out, there are additional factors to consider.
In his article, Anderson also challenges what he refers to as “the most popular explanation for prolonged preservation” of soft tissue. Namely, the “iron model.”10 In part 2 of my response to Kevin Anderson, I will describe and respond to his critique of the iron model and other preservation mechanisms.