The worst birthday present ever lead to the discovery of colorblindness by John Dalton all the way back in 1794. Mister Dalton bequeathed his eyes to science. Two hundred years later, science made use of them.
John Dalton was one of the first people to identify the heredity of colorblindness. It took quite some time for anyone to realize that some people couldn't see colors the way others could. Even when it was identified, the phenomenon was never examined. What did it take for a study to be made of color blindness? A very clever person who discovered that he was colorblind. John Dalton was a smart young Quaker who taught school by the time he was a teenager and as an adult became a physicist. One day he used his earnings to buy a modest pair of blue-brown tights for his mother's birthday. His brother agreed they were nice, but his mother, when she got them, was very upset. They were scarlet.
Since neither John nor his brother had noticed anything amiss, they realized that they couldn't see color the way that other people could. Dalton began studying the way colorblindness was linked to heredity. His conclusions about heredity were correct, but he believed that a discoloration of the fluid in the eyeball caused colorblindness.
The theory came under dispute in his lifetime, so to settle it after his death, he ordered that when he died his eyeballs were to be scooped out and, as it were, decanted. The fluid was normal, and so his theory was disproved.
Science was never one to let a good eyeball go to waste, though, and so they were kept until 1995, when a genetic test was done on them to see what type of colorblindness Dalton had. It worked, and it was discovered that Dalton was a deuteranope. He had a deficiency in the cones of his eye that didn't let him see red or green. Red he saw as a drab brown, and purple looked either dark blue or black. Green looked like a rather subdued orange.
Will we be able to grab some more DNA and construct an entirely new John Dalton someday? Who knows. If we do, don't let him buy you clothes.