My son loves science. Because of that, we have begun watching NOVA on our local PBS station, and have really enjoyed it.
One particular episode I found fascinating dealt with the issue of how smart animals really are. The conclusion was varied, but with certain breeds of dogs it is clear that there exists a certain type of “social intelligence” that is significant. ”Social intelligence” occurs with dogs when they want so much to please their owners, their “pack mates” and “pack leaders” that they learn behaviors that many other animals simply have no interest in pursuing.

Above is Chaser, a border collie who was featured on the program, and can differentiate between 1,022 stuffed animals. You heard me.
His owner, a scientist, decided to see if he could teach Chaser more than your average dog tricks. Over time, he has trained her to identify over 1,000 toys by name.
For instance, on the show, he laid out ten of her stuffed animals in the yard while she was inside. As she returned outside, he told her to ”Find ‘Love Bug’”. She trotted happily off looking through the variety there until she found the right toy, and brought it right back to him.
What’s even more impressive is that the host (shown far left in the above photo with Chaser’s owner and trainer) added a NEW stuffed animal, one Chaser had never seen before. This time, the grouping was made up of nine toys that Chaser knew already – and the one that Chaser did not know. After one false start, Chaser quite correctly deduced that even though she’d never before been told to “Find Darwin” – “Darwin” had to be the one toy she had never seen before. Thus, she brought it back.
You should look for this episode in re-runs on your local PBS station, as it’s fascinating. Here is the link to additional info from a “New York Times” article about Chaser:
Chaser \”New York Times\” article
And if you’re not 100% convinced that this dog really understands…just watch the video in the link to realize that she not only knows 1,002 nouns – she knows her verbs too!