Reasons to Believe

Optical Illusion Exposes Reality of Design

Skeptics like to argue that so-called “bad” designs throughout nature disprove the existence or involvement of a supernatural Creator.

Less-than-optimal designs seem to fit better with an evolutionary explanation. But as a new report on the human pupil demonstrates, most supposed shoddy mechanisms turn out to be optimally designed upon closer inspection.

****

Each day new discoveries provide more evidence for God’s existence and the Bible’s reliability—but the research often remains buried in the academic journals. 

For example, a report in the Proceedings of the National Academy of Sciences about the human pupil’s response to light can help Christians respond to a common challenge leveled by skeptics; namely, bad designs exist throughout nature. In this case, common knowledge says pupils constrict when exposed to bright light, but dilate in dim light. Pupils also dilate when exposed to eye-catching stimuli. 

Researchers from the University of Oslo were interested in understanding the neural pathways involved in these pupillary responses. They observed that the human pupil’s reflexive response to light generates a false positive (constriction) when presented with an optical illusion of brightness. This was a surprise. Because the optical illusions were eye-catching stimuli, the researchers expected them to cause dilation, which would have been the “best” response.

This is the type of discovery that skeptics often point to as an example of a poor design. Some skeptics argue that seemingly less-than-optimal systems in nature fit better with an evolutionary worldview. They say it’s inconceivable that the biblical God would use substandard designs. On the other hand, evolutionary processes are expected to produce “kluge jobs,” biological structures that are just good enough to ensure survivability, but aren’t necessarily optimal. 

Yet, closer examination suggests that this unexpected pupillary response is a good thing. Damage to the retina is permanent. So, it’s better for the pupils to constrict inappropriately when presented with illusions of brightness than run the risk of retinal damage. Plus, as the researchers discovered, the pupils dilated quickly after the initial constriction in response to the optical illusions. It appears that higher-order processes in the brain associated with the interpretation of visual stimuli function as compensatory designs that override the pupillary reflex when it responds incorrectly.

As is often the case, careful consideration or more information show that so-called “bad” designs are, in fact, elegant and highly optimized systems—a conclusion that fits better with the existence of a thoughtful Creator. 

This spring, we’re launching Creation Update 2.0, a new podcast dedicated to shining a spotlight on unsung discoveries like this one. Each week Hugh Ross, Jeff Zweerink, and yours truly will record short descriptions of recent but underreported scientific findings and explore their implications for the Christian faith. 

Subjects: Bad Designs?

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

1. Bruno Laeng and Tor Endestad, “Bright Illusions Reduce the Eye’s Pupil,” Proceedings of the National Academy of Sciences, USA 109, no. 6 (February 7, 2012): 2162–67.