The Development of Green Plants
I’ve never been a fan of things ‘just happening.’ Green plants are not really the best way to absorb the available light we currently have and utilise it in the most efficient way. The sun currently gives off more light in the yellow and green spectrum than in the red area that give green plants the advantage, which is more filtered out. So why are they green. The common pat answer is that they use chlorophyll, a chemical that has been passed down by natural selection. This may also suggest that the red and violet parts of the spectrum were more prominent in the past to give this evolutionary advantage. Evolution seems to work by not replacing the best fitting pattern and advantage, but by adding to or changing that pattern to fit the new environment. Things tend to get added, but in most cases either slowly degenerate, so the original has less importance, but it is rarely removed completely, just side-lined or used in conjunction. For example, we have three main parts of our brains, the oldest, the back part and brain stem, found in many other creatures such as reptiles, but we still use this ‘oldest’ part of the brain rather than evolution having disposed of it.
So what conditions would give an original reddish light to produce an efficient chlorophyll reaction? Conditions in which green and yellow were much less when plants first started to develop. This could be as far back as 1-2 billion years ago when large quantities of cyanobacteria, blue-green algae gave an advantage to allow for red light to filter through and produce oxygen in large quantities, giving a trend towards green plants. The other possibility is that vulcanism or a very large asteroid impact darkened or stained the sky into only really allowing a red haze, and things like the flow in the Siberian Traps producing this effect. Around the time of when the plants first started up there was also a large crater formed in South Africa, the Vredefort crater, dating from around this time that was probably from an estimated 15 mile wide asteroid impact, 30 times the mass of the one that contributed to wiping out the dinosaurs and producing that change in dominant lines. If red is all you have, red is what you use, evolving but never losing this characteristic.