From: HowStuffWorks on Fri, Dec 18 2009 12:31 AM

From: HowStuffWorks on Fri, Dec 18 2009 12:30 AM

From: HowStuffWorks on Fri, Dec 18 2009 12:23 AM

From: HowStuffWorks on Tue, Sep 29 2009 5:29 PM

From the trees to the plains, learn about the evolution of big cats on Discovery Channel’s "Ultimate Guide to Big Cats."

From: HowStuffWorks on Tue, Sep 29 2009 5:18 PM

The law of evolution says that different creatures would evolve in different conditions. On Discovery Channel’s "Science of the Impossible," scientists speculate what aliens would look like in different settings.