Dogs have begun a new era of evolution.
Dogs are beginning a new age of domestication
Scientists believe that pooches are undergoing a third wave of domestication as owners seek pets that will gave them companionship instead of hunting pests and protecting their homes.
Analysis has found that this change has raised the levels of the hormone oxytocin - which is responsible for social bonding in pooches - and that the impact has been particularly noticeable in service dogs.
Canine experts Brian Hare and Vanessa Woods wrote in The Atlantic magazine: "Unlike most pet dogs, service dogs are attracted to strangers, even as puppies.
"And increasing friendliness seems to have changed these dogs' biology, just as it did thousands of years ago."
The pair have also called on humans to help usher in the new age of domestication in man's best friend.
They wrote: "For the happiness of dogs and their owners, humans need to breed and train more dogs like service animals, embarking on a new wave of dog domestication to help them fit into the new world we have created."