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why did moths change color? was Do bicycles and cars mix?
Bob Bayn, Network & Computing Services wrote:
Actually, the moth "changed color to blend in"** with the natural color of the bark of trees instead of the lighter color of the lichens that used to grow on the trees. The pollution levels killed off the lichen. It wasn't just black soot painting the landscape. I am afraid you got it wrong here. The moth in question lives on birch trees, and their bark is naturally white, only in heavily poluted areas they are covered in black sot and dust. Lichens btw are usually either green, yellow or red, not white. This is quite logical too, a white lichen would reflect all light, and have no energy source for photosynthesis. May be you are not old enough to remember how things were in industrialised areas before the environmental movement of the '70s. You actually could not dry laundry outside: it would become black before it became dry. There was a big political drive in those days under the title "we want to see again the blue sky over the Ruhr (an area with a lot of coal mining and iron smelting activity in Germany). I remember train rides along the Rhine river, where we had to keep the windows closed because of the sulfuric stench of the water, which was so chemical loaded that bathing in the river was deadly (it was the then German minister for environment Klaus Toepfer (now head of environmental protection at the UN) who was the first to do so again in a publicity heist after major international cleanup efforts. In the 19th century there had been strikes by servants in cities like Colone because they were given only cheap river salmon for food. Salmon became extinct in the river in the 20th century because of pollution, only now they are slowly returning. Yes, quite a lot has been achieved in the last 30 years, but more needs to be done. And a more considerate use of fossile fuels would be a good start. |
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