Reasons to Believe

Evolution Loses Its Direction

Fossil evidence reveals that evolutionary change is seldom directional.

As a parent, one of my biggest concerns is that my children have a direction for their lives. I don’t want them to waste time aimlessly going through life.

Unfortunately for the evolutionary paradigm, new research indicates that the fossil record has lost its direction. But this loss of direction isn’t bad for a different paradigm. This new insight adds to the evidence indicating that life’s history has a purpose orchestrated by a Creator.

One of the key pieces of evidence cited in support of biological evolution is the fossil record. Evolutionary biologists point out that: 1) the fossil record shows that past life on Earth is different than life today; and 2) simple life preceded complex life-forms. For many scientists these general features indicate that life on Earth must have evolved.

These observations, however, could just as easily be accounted for by evoking the work of a Creator who created in stages, bringing different life-forms into existence at different times in Earth’s history. This pattern accords with the Genesis 1 and Psalm 104 creation accounts.

What about the specific features of the fossil record? Can these patterns find explanation within a creation model context? Or are they best understood within an evolutionary framework?

Given a Darwinian mechanism, it’s expected that the fossil record should display gradual transformations replete with corresponding transitional forms. Over the last 30 years or so paleontologists have debated whether or not the fossil record truly displays this pattern. In the early 1970s, Stephen Jay Gould and Niles Eldredge argued that the fossil record fails to show gradual evolutionary transformations. Instead these two paleontologists maintained that evolutionary change happens suddenly and then periods of stasis, or no evolutionary change, follow. They termed this idea punctuated equilibrium.

Ironically, the pattern proposed by Gould and Eldredge—punctuated equilibrium—is consistent with the work of a Creator and matches the pattern for the fossil record predicted by the RTB creation model. Since its proposal, punctuated equilibrium has been a controversial idea, provoking much debate among scientists about the actual patterns observed in the fossil record.

A recent study published in the Proceedings of the National Academy of Sciences addresses this controversy. The researcher conducting the study examined 250 documented cases in which biological traits were monitored in fossil lineages, statistically assessing the percentage of 1) directional change; 2) random walk; and 3) stasis. He noted that only 5% of the fossil lineages showed directional change while roughly 45% displayed random walks and about 45% stasis. (The 5% of cases displaying directional change most likely represents an overestimate due to a selection effect. Paleontologists are more likely to study fossil lineages that show change than those remaining static.)

In addition to these overarching trends, the statistical analysis also uncovered specific patterns. It turns out that stasis is much more prominent for features related to shape. In contrast, directional trends are more likely to involve changes in body size. Likewise, planktonic microfossils (visible under a microscope) showed a more pronounced tendency to experience directional changes than macroscopic (visible to the naked eye) fossil lineages. More often than not, macroscopic forms displayed stasis.

The statistical analysis supports the central claim of punctuated equilibrium and indicates that directional change in fossil lineages is quite limited.

The patterns uncovered by the study are also consistent with a Creator’s work in life’s history. Organisms created in an optimal state would be expected to experience stasis because virtually any change would cause them to lose fitness. Random walks observed in the fossil lineage could be interpreted as genetic drift and the few cases of directional change are consistent with microevolutionary changes in organismal size or evolutionary advance of microscopic creatures with large population sizes.

The patterns uncovered by this study are provocative in light of the analysis of life’s history conducted by biologist Eugene Koonin, discussed previously. Koonin demonstrated that life’s history is best described as a sequence of biological big bangs with little, if any, evidence for intermediate forms.

Still, can punctuated equilibrium account for the patterns observed in the fossil record without evoking the Creator’s hand?

I will discuss this question next week.

Subjects: Speciation Events, TCM - Speciation, Transitional Forms

Dr. Fazale Rana

In 1999, I left my position in R&D at a Fortune 500 company to join Reasons to Believe because I felt the most important thing I could do as a scientist is to communicate to skeptics and believers alike the powerful scientific evidence—evidence that is being uncovered day after day—for God’s existence and the reliability of Scripture. Read more about Dr. Fazale Rana