Lots of New Contributing Editors

I'm just curious. How does BlogHer pick Contributing Editors and decide which topic areas they fill? Sometimes it seems that there are several CE's that cover roughly the same topic areas and only one or two in other areas.

For instance, there are lots of feminist and tech CEs but only one travel CE, one Craft CE, one Religion CE etc. Is this simply the way things evolved, or are CEs and topics chosen by demand or popular interest?

Also, are CE's chosen at random, by BlogHer members who have come across them, or do they apply for the positions?.....is that too nosy to ask?