Pingelap Atoll, a Micronesian island in the South Pacific, sometimes goes by its other name, the Island of the Colorblind. That's the moniker Oliver Sacks assigned the island in his 1996 book that explored the human brain. Pingelap piqued the interest of Sacks and many other scientists because of its strange genetic circumstance. According to legend, a devastating typhoon in 1775 caused a population bottleneck. One of the survivors, the ruler, carried a rare gene for an extreme type of color blindness. Eventually, he passed the gene to the island's later generations.

Today roughly 10 percent of the island's people are still believed to have the gene for the condition, known as complete achromatopsia, a rate significantly higher than the one-in-30,000