How and why are the human race able to communicate with each other? Why do we understand each other?

Question: How and why are the human race able to communicate with each other? Why do we understand each other?
- Keywords:
  human,
  neuroscience,
  psychology,
  society
Asked by Maddie to Lisa on 17 Nov 2014.
- Lisa Simmons answered on 17 Nov 2014:
  
  Most animals communicate with each other in some form or another, some use sound like we do and others can use chemicals such as pheromones. The ability to communicate is key to a species survival.
  In humans, communication is a factor of conditioning, we learn to communicate as we grow up, this isn’t always in the form of speech, for example, sign language.
  I’m not a neuroscientist so I couldn’t tell you the exact part of the brain that has developed in humans which has enabled speech. It’s an excellent question, sorry the answer is so vague.

Question: How and why are the human race able to communicate with each other? Why do we understand each other?