This is a nice article written at an appropriate level of detail for Scholarpedia.
I have made a couple of minor changes to the text including marking the sub-headings so as to generate a table of contents.
It would be good to see the article revised a little in the following respects: i. To be consistent with Scholarpedia article style the introductory paragraph should provide a short, dictionary-like definition of the topic (see http://www.scholarpedia.org/article/Scholarpedia:Instructions_for_authors). ii. It would be nice to see bit more of a comparative/evolutionary perspective as the current article is fairly human-centric.