Popular Science teems with nerds who loves dogs. I'm certainly in that category, and you probably are, too -- hey, I didn't click the link with "science" and "dogs" in it. So here are some nerdy dog statistics: Nearly as many pet dogs exist in the United States as human children. More precisely, about 70 million dogs curl up in 36.5 percent of homes, compared to 78 million kids living in 45 percent of homes. What's more is that dogs are smart. Very smart. With the proper training, some can learn more than 1,000 words, among other intellectual feats.