Dogs clearly were not in that group. Wayne now believes that dog and human interactions went through three primary stages:
1- Hunter gatherers, possibly even Neanderthals, interacted with dogs, probably benefiting from their presence. For example, dogs might have kept other, more dangerous, carnivores out of the way. They could have also helped with hunting.
2- With the emergence of agriculture, dogs lived near humans and adapted to an agricultural diet. Prior studies have found that dogs in such regions possess higher numbers of amylase genes that help to digest starch. Wolves have these genes too, the scientists found, but usually not in such high amounts.
3- In more recent history, humans have selectively bred dogs, which has dramatically changed the appearance, behavior and other attributes of dogs.
Throughout this overall period of time, interbreeding with wolves occurred, and still happens, further complicating the genetic relationship between wolves and dogs.
Elaine Ostrander, an investigator at the National Human Genome Research Institute, told Discovery News, "This paper is exciting for students of canine history as well as dog owners because it clarifies the events leading up to dog domestication. We now know that it was not a single event, but several, which makes sense when we think about the extraordinary variation that we seen in modern dogs."
She added, "We also know that the critical intermediate -- the dog/wolf -- is not alive on the planet today. However we don't know why. Did is suffer from some infectious disease, a plague of sorts? Was it killed off by other animals? Did it starve?"