The bond between humans and dogs isn't just psychological or the common love of bacon.
It's also genetic.
For about 15,000 years, dogs have migrated in lockstep with humans around the globe. They have followed us from Asia into Europe, North America and back to Africa — all the while hunting, protecting and snuggling us.
Now it looks as though dog DNA has evolved in lockstep with our DNA.
Scientists in China have found evidence that dogs developed protection against malaria in the same way that people in West Africa have.