This morning my classmate and I were walking to college and both sneezed at the sight of the sun. There’s an article on NewScientist that explores the possible reasons for this apparently common reaction to the sun’s light.

Mahmood Bhutta offers the hypothesis that it is to do with crossed ‘wires’ in our nervous system. From the article:

All these nerve responses flow to and from regions of the medulla close to where the sneeze centre is located. This suggests that far from being a neat system of discrete responses to individual stimuli, our reflex systems at their base in the medulla are often a tangled web of cross-talking nerve wires. Sometimes when bright sunlight hits our eyes, the parasympathetic system responds appropriately and our pupils constrict. But for certain people whose medullas are wired differently, sunlight triggers a different reflex response, such as a sneeze.

Nervous overkill is no deal breaker in the survival stakes as long as the right reflexes are also stimulated at the right time, so aberrant genes that cause confused reflexes in some individuals would have been conserved by evolution. “It’s a mess,” says Bhutta, “because it’s never had to be anything else.”

Read more at NewScientist