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The genes that are responsible for colour blindness are also responsible for causing tetrachromacy. Colour blindness is seen as a deficiency, requiring a cure

by femto 8y ago

The genes that are responsible for colour blindness are also responsible for causing tetrachromacy. Colour blindness is seen as a deficiency, requiring a cure, whereas tetrachromacy is seen as an enrichment, yet they are different aspects of the same thing (a mutated cone). "Cure" one and you "cure" the other. When it comes to genes, where do we draw the line between a difference and a disorder? Disorder is in the eye of the beholder (no pun intended)?

Dylan16807 8y ago
Has functional tetrachromacy actually been confirmed in humans? If the gene variant breaks the cones, then it's a disorder. If they function fine then it's not a disorder, even if they're different. Why would curing one "cure" the other?
- femto 8y ago
  According to a link from a Snopes article, yes. http://www.digitaljournal.com/article/326976 http://www.digitaljournal.com/article/326976 In a not so rigorous way, others claim they are. For example: http://nymag.com/scienceofus/2015/02/what-like-see-a-hundred-million-colors.html http://nymag.com/scienceofus/2015/02/what-like-see-a-hundred... Apparently the theory is that a mutation on an X chromosome causes a wonky typically non-functional cone. A male, with one X chromosome gets 2 normal cones and 1 wonky one. A female, with two X chromosome can get 3 normal cones from one X and 2 normal cones and 1 wonky one from the other X, for a total of 4 types of cone. If the wonky one happens to be working they are a tetrachromate. Thus eliminating the gene that causes wonky cones eliminates colour blindness and tetrachromacity. I wonder to what extent the wonky cone in a colour blind male typically functions? They wouldn't necessarily see fewer colours but different colours. The red-green colour blind people I know can still see the colours as different, just not as distinctly based on their saturation, background colour and whether they are doing a direct comparison. Presumably there is also the remote possibility of a colour blind female being a tetrachromate? Additional edit: The world is greyer than something simply functioning or not. Assuming a solid definition of "functioning", something can be partially functioning. More generally, one first has to figure out what functioning means.

by femto 8y ago

Dylan16807 8y ago

Has functional tetrachromacy actually been confirmed in humans? If the gene variant breaks the cones, then it's a disorder. If they function fine then it's not a disorder, even if they're different. Why would curing one "cure" the other?

femto 8y ago
According to a link from a Snopes article, yes. http://www.digitaljournal.com/article/326976 http://www.digitaljournal.com/article/326976 In a not so rigorous way, others claim they are. For example: http://nymag.com/scienceofus/2015/02/what-like-see-a-hundred-million-colors.html http://nymag.com/scienceofus/2015/02/what-like-see-a-hundred... Apparently the theory is that a mutation on an X chromosome causes a wonky typically non-functional cone. A male, with one X chromosome gets 2 normal cones and 1 wonky one. A female, with two X chromosome can get 3 normal cones from one X and 2 normal cones and 1 wonky one from the other X, for a total of 4 types of cone. If the wonky one happens to be working they are a tetrachromate. Thus eliminating the gene that causes wonky cones eliminates colour blindness and tetrachromacity. I wonder to what extent the wonky cone in a colour blind male typically functions? They wouldn't necessarily see fewer colours but different colours. The red-green colour blind people I know can still see the colours as different, just not as distinctly based on their saturation, background colour and whether they are doing a direct comparison. Presumably there is also the remote possibility of a colour blind female being a tetrachromate? Additional edit: The world is greyer than something simply functioning or not. Assuming a solid definition of "functioning", something can be partially functioning. More generally, one first has to figure out what functioning means.