> There are other clues too: why do a small percentage of women have superior color resolution in the green spectrum (as if they had multiple green channels)
Apparently a small number of women have Tetrachromacy, where they have a 4th type of cone in their eye and can see a much broader range of colors, thanks to their genes. The gene isn't super-rare (I think one article claimed ~12% of women have the genetic condition for it), but the functional ability to perceive with all 4 types of cones is very rare. https://www.bbc.com/future/article/20140905-the-women-with-s... has a story about one confirmed case.
Right tetrachromacy is proven and I've learned the hard way never to argue with women who insist there are shades of color that I cannot see. Moreover, these women make excellent color graders (in film work, etc.) as their output is more consistent.
My comment was made in the general sense from a modeling perspective. The trouble is - as you've implied - things get very complex once one scratches the surface especially so with seeing and perception as one's interpretation is also subjective and we don't have an adequate language to describe what we see. That's why calibration and measurement are so important.
These difficulties also likely account for why there's been a 91-year delay between the '31 CIE work and this discovery.
Incidentally, I've just noticed that Adrian_b makes the point that the "non-Riemannian nature of perceptual color space" has been known for decades. In hindsight, I should have strengthened my earlier comment about the evidence behind this new work having been known about for some considerable time.
Apparently a small number of women have Tetrachromacy, where they have a 4th type of cone in their eye and can see a much broader range of colors, thanks to their genes. The gene isn't super-rare (I think one article claimed ~12% of women have the genetic condition for it), but the functional ability to perceive with all 4 types of cones is very rare. https://www.bbc.com/future/article/20140905-the-women-with-s... has a story about one confirmed case.