This quote is suggesting that humans have been able to stay alive and thrive as a species due to their long-term friendship and relationship with dogs. Dogs provide humans with protection, companionship, and other benefits, and humans have been able to use these benefits to help keep them safe and healthy. This quote also suggests that if not for this bond between humans and dogs, our species may have gone extinct long ago. The friendship between humans and canines is a very special one, and it has helped us stay alive and continue to thrive as a species.