It turns out I didn't grasp what the authors meant by "colorful signals". They're talking specifically about vivid colors that serve an evolutionary purpose, and in that case it seems rather clear that vision would have to come first. That is in fact also what turns out to be the findings.
While the article is a fun and light read about some scientists doing some literature review to try and approximate when color as a signal evolved, I'm afraid the error bars are so large it's hard to find any certainty.
The article does end with some speculation that vivid color can't actually evolve without eyes that produce a natural selection bias, since vivid color takes effort to construct. That claim of course has the same efficacy problems as what the article is mainly dealing with, but I do find it somewhat convincing, and have lowered my certainty that vivid colors actually evolved first.
Thanks for your thoughtful comments. I'm inclined to think colour occurred first, but there is of course no way to be sure. From our point in geological time, this is a good test of our knowledge and methods, but we are missing a significant amount of data. Several major extinction events precede us.
From TFA:
"Color vision likely evolved twice independently, [Wiens ] found, and around the same time: between 400 million and 500 million years ago in arthropods, such as insects, and in backboned animals, such as fish. That places the evolution of color vision 100 million or 200 million years before any color signals."
At least twice...
"Wiens and Emberts’ data supports the hypothesis that color evolved for some as-yet-unknown reason before any of these flashy signals. “It was color vision first, then fruit, then flowers, then warning signals and then sexual signals,” Wiens said."
Angiosperm ancestors occurred more than 300 mya [1]. Insects are older [2]. When insects and flowers evolved the commensal relationships that we know so well today, the ensuing population growth and diversification is termed an "explosion" for good reason.
Tigers and such feel like a good counter example to colors needing eyes to see them? Specifically, the color of tigers is largely evolved against eyes that don't see the orange.
As such, many colors would be expected in environments that don't confer an advantage to colors. And once an environment starts to give advantage, you would expect rapid convergence.
Which, maybe I'm just reinforcing old learning of mine? Moths were a specific way of teaching evolution in my grade school, and they acted exactly as I just described. With soot covered areas growing rise to black colorings and cleaner air giving rise to the opposite.
It looks like by "colorful signals" they mean colorful surfaces of animals and plants, in the case when those colors are not colors necessary for the function of some vital organ, e.g. the pigments that capture light in plants or the red iron-based or blue copper-based respiratory pigments (such pigments have appeared before vision organs).
It turns out I didn't grasp what the authors meant by "colorful signals". They're talking specifically about vivid colors that serve an evolutionary purpose, and in that case it seems rather clear that vision would have to come first. That is in fact also what turns out to be the findings.
While the article is a fun and light read about some scientists doing some literature review to try and approximate when color as a signal evolved, I'm afraid the error bars are so large it's hard to find any certainty.
The article does end with some speculation that vivid color can't actually evolve without eyes that produce a natural selection bias, since vivid color takes effort to construct. That claim of course has the same efficacy problems as what the article is mainly dealing with, but I do find it somewhat convincing, and have lowered my certainty that vivid colors actually evolved first.