Read this: The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Dogs had a worth to what type of early humans?
hunter-gatherers