There is no known general principle by which contact between humans and other animals would consistently lead to the other animals getting smarter over long times. Evolution works purely by the effects of some creatures reproducing more than others, making the typical population change over time. Without understanding what makes some types reproduce more than others, we can't make predictions.
When we deliberately set out to breed animals or plants with certain traits, we can make them evolve quite rapidly. For example , broccoli, cabbage, kale , cauliflower, brussel sprouts, kohlrabi, collards and some other crops are all descended from a recent common ancestor, and deliberately selected by people for various traits. So if people decided to breed very smart dogs, we could do so.
So far as I know, the general impression is that we may have done the opposite with most of our domestic species. People I know who work with animals usually have the impression that wild cats, wolves, wild cattle, etc. are at least as smart as their domestic cousins. However, domestic dogs are very well-tuned to pick up on the emotions of people, so in that sense I guess you could say they're smarter. It's a reminder that there are all sorts of smarts, so that one type might increase and another might decrease.
It's quite uncertain whether we ourselves will have any descendants 1,000,000 years from now. If so, we don't know in what ways they will be smarter or stupider than us.
(published on 11/19/2010)