When we brought our new baby home from the hospital, our dog Tassie was faced with a dilemma. Since the day we adopted him from a shelter as a puppy, Tassie has had a basket of stuffed toys. Growing up, his favorite activity was to rip out the stuffing and leave it all over the house. Every now and then we would fill up the basket with new toys he could rip up all over again. We also gave our baby, Malou, a basket of stuffed toys, which was almost identical to Tassie''s. As Malou started to crawl, she quickly developed the habit of dragging the toys out of her basket and leaving them all over the house. Here was the dilemma. Of the dozens of toys, Tassie had to figure out which ones were his to rip up, or Malou was going to find her favorite toys in a heap of stuffing and there would be trouble.

Tassie turned out to be rather good at it. Of course, we were hopeful Tassie would have this ability, since Brian''s colleague at the Max Planck Institute for Evolutionary Anthropology in Germany, Juliane Kaminski, studied a dog named Rico who had solved a similar problem. Kaminski received a phone call one day from a very nice German lady saying she had a Border collie who understood more than two hundred German words, mostly the names of children''s toys. This was impressive but not unheard of. Language-trained bonobos, bottlenose dolphins, and African grey parrots have learned a similar number of names for objects. What was different about Rico was how he learned the names of these objects. If you show a child a red block and a green block, then ask for "the chromium block, not the red block," most children will give you the green block, despite not knowing that the word chromium can refer to a shade of green. The child inferred the name of the object.

Kaminski gave Rico a similar test. She placed a new object Rico had never seen before in a different room with seven of his toys that he knew by name. Then she asked him to fetch a toy using a new word he had never heard before, like Sigfried . She did this with dozens of new objects and words. Just like children, Rico inferred that the new words referred to the new toys. Without any training, Tassie has never ripped up one of Malou''s toys instead of his own. His toys and her toys can be lying in a jumble on the floor, and he will carefully extract his toys and play with them, giving her toys only a longing glance or a quick sniff. He adapted quicker than we did to life with a new baby.

* * * In the last ten years, there has been something of a revolution in the study of canine intelligence. We have learned more about how dogs think in the past decade than we have in the previous century. This book is about how cognitive science has come to understand the genius of dogs through experimental games using nothing much more high-tech than toys, cups, balls, and anything else lying around the garage. With these modest tools, we have been able to peer into the rich cognitive world of dogs and how they make inferences and flexibly solve new problems. Thinking about dog genius will not only help us enrich their lives but also broaden how we think about human intelligence. Many of the same concepts used to study dog intelligence are being applied to humans. Perhaps the greatest gift our dogs will give us is a better understanding of ourselves. Everyone has an opinion about what makes dogs smart.

There is now an extensive scientific literature examining dog psychology that sometimes supports or doesn''t support these opinions. To help all dog lovers debate what the latest scientific findings might mean, this book provides a comprehensive review of dog cognition, or "dognition." We have read thousands of scientific papers relevant to the study of dog cognition, and we reference more than six hundred of the most important and interesting of these papers in this book. If you are interested, there are ways to get access to these papers and read them for yourself.* While our review is comprehensive, it covers only areas that have been scientifically studied. We may not cover some areas of interest simply because no scientist has published anything on the topic. But on the flip side, there is tons of fascinating research on dognition you may never have imagined. Although we have done our best to represent the literature fairly, not every scientist will agree with everything we report.

Whenever we could, we highlighted alternative perspectives or competing data in the main text. But for ease of reading, we have provided extensive notes at the back of the book that cover important details and alternative findings when they are available. Disagreement and debate in science are healthy and exciting. Disagreement often drives research that leads to advances in our understanding. Scientists rely on skepticism and empirical debate as a road to the truth. So do not be alarmed if your intuition or your own observations lead you to be skeptical of some of the evidence we present. You are just being a good scientist. We hope that when you finish this book, your new knowledge, combined with your own observations, will lead to interesting discussions and debates with your fellow dog lovers.

Through these debates, we can learn how to have an even richer relationship with our dogs. We can also identify areas where we need more understanding or where scientists have not even asked the right questions. This is all part of the fun. What we know for certain is that the cognitive world of every dog is far more complex and interesting than we thought possible. We also have a tantalizing glimpse into the secret of their success. We can now pinpoint the stuff of dog genius. Brian had the good fortune to play a significant role in the unfolding of this story of discovery--as did his childhood dog Oreo. Some of what is laid out in the following pages will shock even the most knowledgeable dog owners.

It is not always obvious where dogs will show an ability to make inferences or show more flexibility than other species. But in the end, your intuition is correct--your dog is a genius. The many flavors of genius Can I really be serious about the title? Most dogs can do little more than sit and stay, and can barely walk on a leash. They are baffled when a squirrel disappears up a tree by circling the trunk, and most will happily drink out of the toilet bowl. This is not the profile of a typical genius. Forget Shakespearean sonnets, spaceflight, or the Internet. If I used the clichéd definition of genius, this would be a very short book. I am serious, and hundreds of studies and the latest research back me up.

This is because in cognitive science, we think about intelligence in animals a little differently. The first thing we look at, when judging the intelligence of animals, is how successfully they have managed to survive and reproduce in as many places as possible. In some species, such as cockroaches, success does not have much to do with intelligence at all. They are just very hardy and excellent reproducers. But with other animals, surviving takes a little more intellect, and a very specific kind of intellect. For instance, it does not do any good composing sonnets if you are a dodo. You are obviously missing the intelligence you need to survive (in the dodo''s case, this was learning to avoid new predators such as hungry sailors). With this as our starting point, the dog is arguably the most successful mammal on the planet, besides us.

Dogs have spread to all corners of the world, including inside our homes, and in some cases onto our beds. While the majority of mammals on the planet have seen a steep decline in their populations as a result of human activity, there have never been more dogs on the planet than today. In the industrialized world, people are having fewer children than ever but are simultaneously providing an increasingly lavish lifestyle for a growing population of pet dogs. Meanwhile, dogs have more jobs than ever. Service dogs assist the mentally or physically disabled, military dogs find bombs, police dogs do guard duty, customs dogs detect illegally imported goods, conservation dogs find scat to help estimate population sizes and movements of endangered animals, bedbug dogs detect when hotels have a problem, cancer dogs detect melanomas or even intestinal cancer, therapy dogs visit retirement homes and hospitals to lift spirits and speed recoveries. I am fascinated with the kind of intelligence that has allowed dogs to be so successful. Whatever it is--this must be their genius. What Is Genius? Most of us have at some time been given a test where scores determine how we are taught or which college we get into.

Alfred Binet designed the first standardized intelligence tests in the early twentieth century. His goal was to identify students in France who should receive extra scholastic attention and resources. His original test evolved into the Stanford-Binet Intelligence Scale, which is known as the IQ test. IQ tests provide a very narrow definition of genius. As you probably remember, tests such as IQ tests, GREs, and SATs focus on basic skills like reading, writing, and analytical abilities. The tests are favored because on average, they predict scholastic success. But they do not measure the full capabilities of each person. They do not explain Ted Turner, Ralph Lauren, Bill Gates, and Mark Zuckerberg, who all dropped out of college and became billionaires.

Consider Steve Jobs. One biographer said, "Was he smart? No, not exceptionally. Instead he was a genius." Jobs dropped out of college, went to find himself in India, and at one point was forced out of Apple, the company he co-founded, when sales were slow.