The U.S. history would be narrower than the width of the line.
Answer:
The populations are isolated and thus do not interbreed.
Explanation:
I'm not sure how exactly you wanted this question to be answered. You're either talking about the symmetry where animals would have two legs or two arms for example and thus producing a pair of each muscle on both sides of the body, or you're refering to the development of agonistic and antaonistic muscles where each of them served a different purpose; either extending or contracting.
The right answer is pluripotent
Yes, because it is found and created naturally