I would have never thought that they could have done this.

So we have smart rodents now?

http://www.livescience.com/animals/080331-degu-rake.html

Rats have almost dominated the intelligence spectrum of the rodents. It's amazing that these Japanese researchers have been able to accomplish this. I don't know about negus, but I do know about rats, as I own two myself at the moment. They are rather intelligent little critters, and, many say, as smart as dogs. They are even playful and can understand how to learn tricks as well as their names and names of other things (such as "treat" for example!).