Dogs have been at our side longer than any other animal in history. They have made us better hunters and better farmers, saved our lives and protected us from harm. And even though dogs may come in all shapes and sizes, they all have one thing in common – they seem to love us. If you were designing the perfect companion for humans, you’d probably end up with something like a dog.

So, how did we get so lucky?

In this show, we unravel the scientific secrets that explain what makes a dog… a dog. We reveal that the emotional bond between human and dog is so profound, it is helping transform the lives of hardened criminals in the US prison system convicted of the most violent crimes.

We examine a 30,000-year-old Belgian wolf skull that some believe marks the first transition from wolf to dog. Many scientists suspect that it is the arrival of us, modern humans, that transformed grey wolves into dogs.

We visit a fox farm in Siberia where a unique selective breeding experiment has been going on for 60 years. This programme helps to explain how the presence of humans transformed the biology, behaviour and appearance of wolves. Some scientists suspect that wolves may have even initiated this process themselves through self-selection.

We go to a dog show to explore the huge variety of shapes and sizes we see in modern dogs and reveal that dogs share a unique ability to vary shape and size by altering just a handful of genes. The Dog Genome Project is discovering that what drove most of this variety was intensive human selection for extreme genes.

We also explore experiments with wolves and dogs at the Wolf Science Centre in Austria, which reveal that the common assumption that our bond with dogs results from selection for intelligence is simply wrong. In fact, recent scientific studies suggest that what makes dogs seem intelligent to us is their unique emotional make-up. It turns out that the secret of our bond with dogs may be love. Not our love for them, but their love for us. MRI scanning of dogs’ brains in Atlanta, Georgia, seems to confirm that dogs genuinely love us.

We visit Callie Truelove, a young girl living with the rare genetic condition Williams Syndrome. This makes Callie extremely loving and sociable. But geneticists have discovered that the same mutations that give Callie her super social nature have also been found in dogs. Some scientists suspect that this is the true secret behind what makes the dog humanity’s best friend. Show less