Natural Selection - Crash Course Biology #14
Hank guides us through the process of natural selection, the key mechanism of evolution. Crash Course Biology is now available on DVD! http://dftba.com/product/1av/CrashCourse-Biology-The-Complete...
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Hi, I'm Hank. And I'm a human, but let's pretend for a moment that I'm a moth. And not just any moth, a peppered moth. Now let's pretend that I'm living in London in the early 1800s, right as the industrial revolution is starting. Life is swell. My light-colored body lets me blend in with the light-colored lichens and tree bark, which means birds have a hard time seeing me, which means that I get to live. But it's starting to get noticeably darker around here with all these coal-powered factories spewing soot into the air, and suddenly all the trees have gone from looking like this to looking like this. So thanks to the soot-covered everything, I've got problems. But you know who doesn't have problems? My brother...
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Hi, I'm Hank. And I'm a human, but let's pretend for a moment that I'm a moth. And not just any moth, a peppered moth. Now let's pretend that I'm living in London in the early 1800s, right as the industrial revolution is starting. Life is swell. My light-colored body lets me blend in with the light-colored lichens and tree bark, which means birds have a hard time seeing me, which means that I get to live. But it's starting to get noticeably darker around here with all these coal-powered factories spewing soot into the air, and suddenly all the trees have gone from looking like this to looking like this. So thanks to the soot-covered everything, I've got problems. But you know who doesn't have problems? My brother...
