How Evolution Works, Part 2

Most critics of evolution accept microevolution but are skeptical of macroevolution—the claim that small changes can add up to big changes over long stretches of time. While the particulars of the mechanisms for such change are not all fully understood, there is very little disagreement among biologists that we now have powerful models of macroevolutionary transitions. These models make testable predictions and are continuously being refined by new evidence.

Whales provide a clear example of macroevolution. They are superficially similar to fish, but are, in fact, mammals! Darwin himself wondered whether whales had evolved from mammals on land, but he had no real empirical evidence for such a claim. Now we have impressive evidence.

In 1978 a 49 million year old skull was discovered that belonged to a land-dwelling wolf-like creature whose inner ear structure was curiously similar to that of modern whales. This led to a search for transitional forms, and very quickly a series of fossils spanning about ten million years was found that showed clear signs of increasing adaptation to life in water. The spine and legs were modified to allow for more efficient modes of swimming; nostrils moved toward the top of the skull, later becoming a blow hole; and hind legs eventually shrank to where they could no longer support the animals on land.

Many more fossils fit into this picture of whale evolution—more than 1000 specimens have been discovered in the Valley of Whales in what is now Egyptian desert. Remember these are not necessarily direct ancestors of whales today. That’s not how evolution works. More likely is that these represent related species that were evolving over millions of years. And taken together, they form an impressive picture of significant change in this lineage of mammals. This picture is not the result of wishful thinking or driven by unwarranted assumptions. It has emerged as the result of careful observation of evidence, which leads to the formation of hypotheses; these make predictions of future finds and are tested by observable evidence which is open to the scrutiny of others.

At BioLogos we see this interconnectedness of life as a testimony to God’s creativity. He worked through simple natural processes to fashion dinosaurs and daisies, weevils and warthogs, and human beings in his own image. He could have snapped his fingers to do this instantaneously, but both scripture and the natural world reveal that God delights in working through processes to accomplish his will. Evidence from the fossil record and also in the distribution and comparison of species supports the claim that he worked through evolution. And today we find even more persuasive evidence in genetics.