Two main areas must be covered in order to assess the evidence for evolution: the fossil evidence and the genetic evidence. Over the course of this essay and the one that follows, I will address the history of the fossil record and the evidence that it provides for biological evolution.

Two main areas must be covered in order to assess the evidence for evolution: the fossil evidence and the genetic evidence.  Over the course of this essay and the one that follows, I will address the history of the fossil record and the evidence that it provides for biological evolution.

Paleontological studies have become commonplace and new finds reach the evening news almost weekly.  This widespread interest, however, has not always been the case.  Up through the sixteenth century, a traditional biblical chronology of origins and geology was widely assumed, which held that the earth and all animal and plant life had been created in its present form.  These assumptions began to change by the mid 1600s.  Neils Steenson (1638-1686), better known by his Latin name of Steno, made the (then) astounding conclusion that rocks that resembled living animals were not just curiosities but were actually the long-dead remains of animals and plants.  This observation was echoed by contemporaries such as John Ray and Robert Hooke.  Immediately a question arose: how were they to interpret these remains that were recognized as being related to modern forms and yet looked different? 

Steno was also responsible for the “principle of original horizontality,” which proposed that the layers of earth (strata) that had been deposited were laid down flat.  Using these concepts, naturalists were able to make detailed observations of where certain fossils were unearthed and determine their relationships to each other.  One conclusion seemed constant: the farther one dug, the more the plants and animals differed from the modern ones.  It was also assumed that the farther down, the older the layer.  Thus, a succession of forms was revealed - beginning back in time and leading to the present.

Many workers in the late 17th and early 18th centuries  expanded on these ideas.  James Hutton (1726-1797) argued that the same natural forces that were at work in the present had created the unearthed environments.  This principle became known as “uniformitarianism,” and became the single most important guiding principle of modern geology.  A surveyor by the name of William Smith (1769-1839), who had spent time in southern England working on railroad and canal projects and collecting the fossils made another observation: certain kinds of fossils were always associated with certain kinds of sediments.  He also found that these fossils were always in the same vertical relationship to each other.  This relationship he termed the “Principle of Faunal Succession.”  Using the vast information that he had gathered, the former railroad worker was able to construct a horizontal and vertical map of England, showing the location of these fossils and their associated geological features. Smith’s studies formed the concept of “marker fossils,” that could be used to correlate strata between different areas. The geologist Baron Georges Cuvier (1769-1832) further reasoned that these fossils formed a record of the past life on the earth and his work set the stage for the study of paleontology.

In the next post, I will bring us up to the present and show how paleontology informed the new field of evolutionary biology. I will also show how evolutionary theory has been used to predict many findings in the fossil record.