A complex biological structure with many interacting parts might appear, at first glance, as if it were originally created in its present form with all its interlocking components fully formed and intact. It doesn’t seem possible that they developed step by step via biological evolution. In Darwin’s Black Box, Michael Behe introduces a term that he and other proponents of Intelligent Design use for this concept: irreducible complexity.

Evolution is the biological model for the history of life on Earth. While some consider evolution to be equivalent to atheism, BioLogos sees evolution as a description of how God created all life. Evolution refers to descent with modification. Small modifications occur at the genetic level (in DNA) with each generation, and these genetic changes can affect how the creature interacts with its environment. Over time, accumulation of these genetic changes can alter the characteristics of the whole population, and a new species appears. Major changes in life forms take place by the same mechanism but over even longer periods of time. All life today can be traced back to a common ancestor some 3.85 billion years ago.