The influence of human culture on the domestication of dogs evolved into man being the owner and the animal belonging to man, just like any object that can be bought, sold or even traded. This type of relation, even though replete with affection and positive interactions, began in the domestication stage and remains true today. The domestication process involves changes in morphologic characteristics and also drastically changes some aspects of behavior. When dogs (“wolf”) were wild, they had characteristics and needs that were suppressed and eliminated by human requirements to serve people. According to Hemmer (1990), the animal began to lose its original “perceptual world”. Behaviors such as rapid stress reactions for survival in the wild were overshadowed by characteristics such as docility, less fear and more tolerance of stress reactions. Domestication has led breeds to underdevelop certain important behavior traits such as intra- and inter-specific social behavior. The morphologic consequences are strictly related to the consequences of the behavior. Different physical traits exhibited in behavioral signaling among conspecifics were rendered impossible because of morphologic modification. An example is the signals used by wolves through snout, ears, hair, eyes and tail for fundamental social communication. Some breeds today such as pit bulls and Rottweilers have their ears and tails cut off only to satisfy human aesthetics and vanity. Basset hounds, for example, have hearing and signaling problems because of having fallen ears as opposed to breeds that have their ears in a vertical position. These modifications, in addition to altering or stopping the execution of intrinsic behavior, also cause pain, make animals feel uncomfortable and are often followed by pathologies, hindering their welfare.
According to Price (1984), domestication affects the animal‘s behavioral characteristics quantitatively more than qualitatively. The loss of some characteristics in their behavior correlates to the increase of the response threshold for some stimuli. However, a low response threshold may be connected to constant stimulation. An example of this phenomenon of behavioral absence is the lack of an alert reaction to humans. Wild wolves used to feel suspicious or afraid in the presence of humans as would any other wild species; wolves used to have a response threshold of defense or running away from a human when one would approach. As the domestication process developed, instead of being afraid and running, wolves have developed an affective relation in which the defensive and reluctant behaviors have been left behind. Therefore, their alert reactions to humans began to have a different, higher threshold. Another possible explanation for this phenomenon is that it may be a consequence of a combination of handling stimulations, verbal and gestural communication and also physical proximity between humans and dogs, turning an aggressive reaction, what once was a threat, into a situation in which an immediate reaction is not necessary.
Even though the domestication phenomenon has affected the morphological and behavioral aspects of dogs, an extensive behavioral range remains unchanged in wolves such as sociable aspects, sniffing, digging, and burying. Despite the great morphological divergence, the continuation of these behaviors in the Canis familiaris species maintains a strong connection to its ancestors, the wolves. Chemical, visual, postural, and vocal communications and social interactions with conspecifics are examples of behaviors that were preserved through evolution. Social standards of behavior, for example, may be considered evolutionary traits that have been maintained in the entire Canidae family.
That dogs maintained these behaviors through countless generations shows how much the behaviors characterize the species and thus how essential the behaviors‘ expression is. Having a gregarious ancestor, the dog has a wide and rich manner of social communication. During puppies‘ development, in a stage called socialization, and during the reproduction and hunting stages, social behaviors are extremely important for canids, and this intra-specific contact necessity among dogs remains today in all breeds. Social characteristics include visual, odoriferous and vocal contact with conspecificity as the central aspect. A study by Wells and Hepper (1998) of four hundred and seven dogs individually housed in a shelter demonstrated that animals that are provided with visual access to other conspecifics remained positioned in the pen in a manner in which they could see other dogs significantly longer than animals that did not have this access. This finding demonstrates the great need for contact with other conspecifics. Hubrecht et al. (1992) conducted a study with animals from shelters and laboratories; their study showed that animals housed alone remained inactive for a longer time than dogs in groups, being inactive 54%-62% of the time. In addition to being inactive for longer, those housed in groups spend more time displaying active and investigative behaviors such as inspecting the pen by smelling it for a wider variety of smells in a social environment.
In addition to being social, dogs are extremely responsive to their environment, always looking forward to interacting with their surroundings by several methods of communication, mainly smelling. The canines‘ excellent sense of smell is because of the thousands of smell receptors located in their noses, enabling them to detect some odors with a refined precision, odors that are imperceptible to humans. Currently, breeds with better olfaction such as the Labrador retriever and the German Shepherd are trained to identify specific odors of, e.g., drugs, explosives, people after disasters and, even more recently, cancer in some patients.
Good vision is essential for dogs to execute some tasks for human benefit, such helping in hunts, guiding blind people, helping the police and communicating with conspecifics and humans. When compared to dogs‘ vision, humans‘ must be considered inferior in certain aspects such as acuity, identifying colors, and binocular overlapping. Dogs‘ vision clearly overshadows humans‘ vision in areas such as movement detection, field view, ability to distinguish shades of gray and being able to see with little light.
Like olfaction and vision, vocalization is also of great importance in the communication universe of dogs, either among one another or with humans. Humans‘ communicating verbally with dogs directly affects their behavior. Understanding the dogs‘ emotional state may be possible by focusing on the animals‘ vocalization and posture. The canine vocal repertory is based on 7 types of sounds: (1) bark (in alert situations, land defense, individual identification, play and to ease socialization), (2) howl (in territorial situations, localizing of group members, individual recognition and coordinated activities such as hunting), (3) growl (in defensive situations, danger, play or threat), (4) yelp (when suffering from pain or stress), (5) snore (nose sound, related to barking), (6) groan (under extreme stress) and finally (7) grunt (showing pleasure). These communicative signals are as essential to a mother and puppies as when there is danger or when showing enthusiasm greeting their owners after being left for an entire day.
The positive 12.000-year relation between dogs (wolves) and humans was enabled by the benefits provided by dogs in hunting, chasing and capturing prey and guarding production animals that used to live inside caves and were dangerous. Since that time, humans and dogs have developed some communication shorthand to create more ease between them. Dogs‘ communications is rich in gestures and expressions as well as in vocalizations and body postures that show such emotions as appreciation, fear, aggressiveness, subordination or dominance, and threat. These signals create ease and comprehension between humans and dogs. Dogs have referential, functional and intentional communication with their owners in several activities such as when they require food. Udell et al. (2010) proposed that communication between dogs and humans depends on two stages; the “Two Stages Hypothesis” is related to the animal‘s sensitivity to human actions. These interactions are based on the social interactions between dogs and humans as well as the manner in which animals copy humans‘ body language. Dogs take tips from humans, learning some words from our vocabulary, matching points and recognizing objects. Social stimulations that developed during the natural history of classic conditioning in indoor dogs are crucial to maximizing dogs‘ quality of interaction.
As evolution and canine domestication continued, the proximity and cohabitation of human and dog have enabled the sociability between them. Proximity and cohabitation have facilitated clearer communication and have made contact with humans as important to the species as contact with a conspecific.