On Sunday 11 July 2010 17:37:25 James R. Frysinger wrote: > What disenchants me in particular about the CIE curve (esp. the initial > curve of 1924 [date?]) is its pitiful provenance. As I recall, at least > in part, the data for this "visual brightness" curve was taken by > questionable experimental means on 12 (?) "healthy young males" at Yale. > Modern biology tells us that while men (who are not colorblind) possess > three types of cones (based on three receptor molecules), women can > possess as many as six, due to the genes for chromatic development being > on the X chromosome. It's not atypical for a woman to possess at least > four different receptor molecules; I think the "blue-green" one is the > one normally existing in dual form. Thus, it's not entirely cultural > that women can possess finer color sense than men do; they may be > genetically predisposed.
The maximum is five. The gene for seeing blue is on chromosome 7, so while a woman (or a man) can be heterozygous for it, both alleles are expressed in the same cone. The red and green genes are on X, and in women one of the Xs turns into a Barr body, so if she's heterozygous, half the red-seeing cones have one allele expressed and half have the other. Pierre -- li ze te'a ci vu'u ci bi'e te'a mu du li ci su'i ze te'a mu bi'e vu'u ci
