What is the significance of mirror neurons to human activities and behavior?

Answer 1

Mirror neurons are neurons which are activated both by performing a particular action and also by the observation of that action being performed by another organism.

In humans such neurons are believed to be highly significant in the learning of behaviours, skills, language etc. They are a relatively recent discovery. However, their overall role is still being very actively investigated.

See this article by the well-known neuroscientist V.S. Ramachandran:
http://www.edge.org/3rd_culture/ramachandran/ramachandran_p1.html

Also check out this video and article in PBS:
http://www.pbs.org/wgbh/nova/sciencenow/3204/01.html

And wikipedia:
http://en.wikipedia.org/wiki/Mirror_neurons