The Purple Earth Hypothesis is that the first photosynthetic organisms on Earth used retinal. This molecule absorbs green light, reflecting red and blue. Green light is the most plentiful at Earth's surface today.

Chlorophyll does the opposite, absorbing red and blue and reflecting green. It is said that it evolved to use the red and blue light left over from retinal. Also, the wiki article mentions a 300 million year ice age. Maybe absorbing the green light isn't a good idea when done at a massive scale?

The Purple Earth Hypothesis is that the first photosynthetic organisms on Earth used retinal. This molecule absorbs green light, reflecting red and blue.

Chlorophyll does the opposite, absorbing red and blue and reflecting green. It is said that it evolved to use the red and blue light left over from retinal. Also, the wiki article mentions a 300 million year ice age. Maybe absorbing the green light isn't a good idea when done at a massive scale?