John Dalton’s name is now associated with color blindness, a vision condition that makes it difficult or impossible to distinguish some colors. The British chemist and mathematician was among the first scientists to investigate why color perception could differ from one person to another—and he studied the question because he experienced it himself.
Born on September 6, 1766, in Eaglesfield, in northwest England, Dalton grew up in a Quaker family and had limited formal education. He showed an early interest in mathematics and natural science, began teaching at his village school at 12, and later worked at a boarding school with his brother Jonathan. There he expanded his knowledge and learned Latin, Greek and French.
In 1793, Dalton moved to Manchester to teach mathematics and natural philosophy at New College. He became involved with the city’s Literary and Philosophical Society, where he presented some of his early work. By then, he had noticed that he saw colors differently from most people. In a letter to his former teacher Elihu Robinson, he said that his brother appeared to share his way of seeing.
Dalton pursued the question scientifically. On October 31, 1794, he presented a paper titled “Extraordinary Facts Relating to the Vision of Colours,” describing differences in color perception and proposing an explanation. The work is considered one of the earliest scientific accounts of an alteration in color vision.
His explanation, however, was incorrect. Dalton believed that the vitreous humor—the gel-like substance inside the eye—was blue and acted as a filter that changed how he perceived certain colors. He was so keen to test his theory that he instructed others to examine his eyes after his death. An autopsy in 1844 found that the vitreous humor was completely colorless.
In 1995, scientists analyzed DNA from Dalton’s preserved eyeball and concluded that he had deuteranopia, a form of color blindness that affects the ability to distinguish red from green.
Sources: elDiario.es.