“What a mouse! . . . WHAT A MOUSE!”
The narrator’s exclamation became the signature cry each time the superhero Mighty Mouse carried out the most impossible of feats.
A parody of Superman, Mighty Mouse was the 1942 creation of Paul Terry of Terrytoons Studio for 20th Century Fox. Since then, Mighty Mouse has appeared in theatrical shorts and films, Saturday morning cartoons, and comic books.
Figure 1: Mighty Mouse. Image credit: Wikipedia
Throughout each episode, the characters sing faux arias—mocking opera—with Mighty Mouse belting out, “Here I am to save the day!” each time he flies into action. As you would expect, many of the villains Mighty Mouse battles are cats, with his archnemesis being a feline named Oil Can Harry.
Mouse Fur Discovery
Recently, a team of researchers headed by scientists from the University of Manchester in the UK went to heroic measures to detect pigments in a 3-million-year-old mouse fossil, nicknamed—you guessed it—“mighty mouse.”1 To detect the pigments, the researchers developed a new method that employs Synchrotron Rapid Scanning X-Ray Fluorescence Imaging to map metal distributions in the fossil, which, in turn, correlate with the types of pigments found in the animal’s fur when it was alive.
This work paves the way for paleontologists to develop a better understanding of past life on Earth, with fur pigmentation being unusually important. The color of an animal’s fur has physiological and behavioral importance and can change relatively quickly over the course of geological timescales through microevolutionary mechanisms.
This discovery also carries importance for the science-faith conversation. Some Christians believe that the recovery of soft tissue remnants, such as the pigments that make up fur, call into question the scientific methods used to determine the age of geological formations and the fossil record. This uncertainty opens up the possibility that our planet (and life on Earth) may be only 6,000 years old.
Is the young-earth interpretation of this advance valid? Is it possible for soft tissue materials to survive for millions of years? If so, how?
Detection of 3-Million-Year-Old Pigment
University of Manchester researchers applied their methodology to an exceptionally well-preserved 3-million-year-old fossil specimen (Apodemus atavus) recovered from the Willershausen conservation site in Germany. The specimen was compressed laterally during the fossilization process and is so well-preserved that imprints of its fur are readily visible.
The research team indirectly identified the pigments that at one time colored the fur by mapping the distribution of metals in the fossil specimen. These metals are known to associate with the pigments eumelanin and pheomelanin, the two main forms of melanin. (Eumelanin produces black and brown hues. Pheomelanin imparts fur, skin, and feathers with a light reddish-brown color.) As it turns out, copper ions chemically interact with eumelanin and pheomelanin. On the other hand, zinc (Zn) ions interact exclusively with pheomelanin by binding to sulfur (S) atoms that are part of this pigment’s molecular structure. Zinc doesn’t interact with eumelanin because sulfur is not part of its chemical composition.
The research team mapped the Zn and S distributions of the mighty mouse fossil and concluded that much of the fur was colored with pheomelanin and, therefore, must have been reddish brown. They failed to detect any pigment in the fur coating the animal’s underbelly and feet, leading them to speculate that the mouse had white fur coating its stomach and feet.
What a piece of science! . . . WHAT A PIECE OF SCIENCE!
Soft Tissues and the Scientific Case for a Young Earth
Paleontologists see far-reaching implications for this work. Roy Wogelius, one of the scientists leading the study, hopes that “these results will mean that we can become more confident in reconstructing extinct animals and thereby add another dimension to the study of evolution.”2
Young-earth creationists (YECs) also see far-reaching implications for this study. Many argue that advances such as this one provide compelling evidence that the earth is young and that the fossil record was laid down as a consequence of a recent global flood.
The crux of the YEC argument centers around the survivability of soft tissue materials. According to common wisdom, soft tissue materials should rapidly degrade once the organism dies. If this is the case, then there is no way soft tissue remnants should hang around for thousands of years, let alone millions. The fact that these materials can be recovered from fossil specimens indicates that the preserved organisms must be only a few thousand years old. And if that’s the case, then the methods used to date the fossils cannot be valid.
At first glance, the argument carries some weight. Most people find it hard to envision how soft tissue materials could survive for vast periods of time, given the wide range of mechanisms that drive the degradation of biological materials.
Preservation Mechanisms for Soft Tissues in Fossils
Despite this initial impression, over the last decade or so paleontologists have identified a number of mechanisms that can delay the degradation of soft tissues long enough for them to become entombed within a mineral shell. When this entombment occurs, the degradation process dramatically slows down. In other words, it is a race against time. Can mineral entombment take place before the soft tissue materials fully decompose? If so, then soft tissue remnants can survive for hundreds of millions of years. And any chemical or physical process that can delay the degradation will contribute to soft tissue survival by giving the entombment process time to take place.
In Dinosaur Blood and the Age of the Earth, I describe several mechanisms that likely promote soft tissue survival. I also discuss the molecular features that contribute to soft tissue preservation in fossils. Not all molecules are made equally. Some are fragile and some robust. Two molecular properties that make molecules unusually durable are cross-linking and aromaticity. As it turns out, eumelanin and pheomelanin possess both.
Figure 2: Chemical Structure of Eumelanin. Image credit: Wikipedia
Figure 3: Chemical Structure of Pheomelanin. Image credit: Wikipedia
When considering the chemical structures of eumelanin and pheomelanin, it isn’t surprising that these materials persist in the fossil record for millions of years. In fact, researchers have isolated eumelanin from a fossilized cephalopod ink sac that dates to around 160 million years ago.3
It is also worth noting that the mouse specimen was well-preserved, making it even more likely that durable soft-tissue materials would persist in the fossil. And, keep in mind that the research team detected trace amounts of pigments using sophisticated, state-of-the-art chemical instrumentation.
In short, the recovery of trace levels of soft-tissue materials from fossil remains is not surprising. Soft-tissue materials associated with the mighty mouse specimen—and other fossils, for that matter— can’t save the day for the young-earth paradigm, but they find a ready explanation in an old-earth framework.