how was the world invented and how were we made as boys and girls and why dont we have each others body parts???

Question: how was the world invented and how were we made as boys and girls and why dont we have each others body parts???
- Keywords:
  body,
  quirky
Asked by rebecca to Jodi on 12 Nov 2014.
- Jodi Schneider answered on 12 Nov 2014:
  
  I really don’t have an answer to that one, Rebecca!
  
  Since you’re interested in biology, you might want to look up different animals to see how they’re different. Not every species has “boys and girls”. For instance, protozoa are made of just one cell. They reproduce by dividing.
  
  Do you know about evolution? Here’s an article that might help to get started:
  http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_14

Question: how was the world invented and how were we made as boys and girls and why dont we have each others body parts???