by Fr. Nicanor Austriaco, OP
Fossils, from the Latin, fossilis, which means “dug up from the earth,” are the remains or impressions of prehistoric organisms preserved as a mold or a cast in rock. Today, the term is reserved for impressions or remains that are at least 10,000 years old.
Fossils have been studied for thousands of years. The ancient Greeks described the fossils of marine organisms and concluded that the land was once under water. The ancient Chinese thought that they were the remains of dragons. Today, our best explanation for the fossil record is that fossils are prehistoric remains of now extinct organisms that lived on our planet sometime over the past 3.5 billion years.
What does the fossil record reveal about the history of life on our planet? First, it reveals that the origins of life are very ancient. There are fossils of photosynthetic bacteria in rocks in Western Australia that are 3.5 billion years old. Second, the fossil record shows that God created life over a long period of time, gradually using natural forces to diversify living things from simple one-celled organisms to more complex ones. Third, it indicates that the evolution of one form of life to another was often gradual over millions of years with intermediate transitional forms of life, though dramatic transformations can also be identified in the fossil record.
To illustrate some of these generalizations, let us examine the fossil record of one very striking evolutionary change, the transformation of lizards into snakes.
The similarity in the natural form of lizards and snakes indicates that they have common origins. God created the lizards about 240 million years ago. The fossil record reveals that He created the snakes about 150 million years ago. How did He do this? Again, as I explained in my first post in this disputatio, God created snakes through instrumental causes in nature that transformed some ancient lizards into snakes by extending their spines, eliminating their legs, and reshaping their skulls.
Two strands of evidence support this claim. First, we have identified fossils of transitional life forms that reveal this evolutionary change. For example, archaeologists have found fossils of an ancient legged snake called Najash that still had hind legs. What is striking is that Najash has a skull that has some of the flexible joints found in modern snakes but not all of them. Its middle ear is intermediate between that of modern lizards and modern snakes and unlike living snakes it retains a well-developed cheekbone, which lizards have but snakes do not have. It is a true transitional form.
I am often asked: If transitional life forms existed in the past, why don’t they exist today? What is striking however is that we do have living transitional life forms that illustrate the evolutionary change between lizards and snake. Legless lizards are common today! Some lizards have lost their front legs; some have lost their hind limbs; while others have even lost both sets of limbs. We even have living lizards that have greatly reduced limbs which are not used for movement. These living transitional forms indicate that the transitional lizards found in the historical record were indeed robust living organisms and not “broken” kinds of animals.
Second, we have begun to understand the genetic changes that accompanied the lizard-to-snake evolutionary change in form that we see in the fossil record. One of the genes involved is Oct4. High levels of Oct4 extends the body length of mouse embryos, and the exceptionally long bodies of snakes likely result from changes in Oct4 behavior during the early development of the embryo. Another gene is Sonic hedgehog (Shh). Changes in Shh have been linked to the loss of limbs in snakes. In fact, molecular biologists can eliminate legs in mice by simply modifying their Shh gene.
Together these two strands of evidence – the fossil record that reveals that transitional forms between lizards and snakes and the molecular evidence that reveals the genetic changes that were involved in this transition – support the claim that God created snakes from lizards using evolutionary forces as instrumental causes.
Though the evolutionary transformation of some ancient lizards into snakes is only one transformation among the many that define the landscape of evolution, I describe it here because it is one of the most striking evolutionary changes for which we have both robust fossil and molecular evidence. It is my paradigm example because it explains well why I am convinced that God created through an evolutionary process.
Some will object. Some will say that we still do not have adequate evidence for the evolutionary transformation that took place that evolved some of the ancient lizards into modern snakes. They will say that all the evidence is circumstantial. We still have not “seen” a lizard change into a snake. Instead, it could be that God specially created the lizards, both the legged and legless forms, and the snakes independently at different moments in prehistory. He simply created them in a way that seems like they evolved from one to another.
The problem with this view is that it suggests that God set things up in nature to trick us into thinking that the fossil and molecular evidence supports an account of evolutionary change when in truth this convergence of the evidence would only be a mirage. This would destabilize our ability to even do science because we could never be sure if the evidence of nature would be reliable. More importantly, this trickster god would not be the Creator God who created us so that we could know the universe that He created for us.
Our objectors may then retort that we can reject an evolutionary account of change despite fossil and molecular evidence that seems to support this view because evolutionary change is simply not reasonable for the believer. It is unreasonable because it defies sound philosophical reasoning and contradicts the testimony of scripture.
As I will explain in later posts, however, this objection fails. It does not acknowledge that human reason can propose a robust philosophical account that explains evolution and a robust theological account that explains how God wrote the sacred scriptures in a way that does not contradict the findings of human reason engaged in scientific inquiry.
Finally, others will say that all the fossil and molecular evidence simply indicates that snakes and lizards belong to the same natural kind. Snakes and lizards are both lizards in the same way that German shepherds and Chihuahuas are both dogs.
The problem with this view is that it suggests that our intellects are unable to properly discern the essences of living things. We could never trust if we could ever know what a thing is. Instead, we should affirm that lizards and snakes are different kinds of things as our intellect grasps and that God created them in the way that evolutionary creation suggests that He did. Both of these are reasonable claims.