Montag, 11. August 2014

The Active social Domestication of the Dog

Really: dogs are mens best friends and positive effects of dog facilitated therapy are well known in medical an pedagogic treatment today. But whats the reason?

Searching for an answer we - Daniela Pörtl and Christoph Jung - have got involved in biology, neurology, psychology, archaeology and epigenetics and developed the model of active social domestication from the wolf to the dog. In our model we will try to explain why.

Our statements are:
  • Genetic selection is a necessary prediction of but not a sufficient explanation for changes from the wolf to the dog.
  • Domestication is essentially an epigenetic based process of modulation of CNS neurotransmitter activities.
  • Dogs dispose of new qualities, which are:
    - increased prefrontal inhibition / empathy concerning to humans (basic ToM) and
    - increased learning ability regarding to human behavior
  • Eventually dogs became multipurpose and active working and social partners to humans.
Dogs are multipurpose and active working partners to humans for more than 10.000 years. (Photo: Christoph Jung)
Hence dogs had become true mutual bonding partners to human and could have been integrated in human social behavior structures.
A fragment of a large bone, probably from a mammoth, Pat Shipman reports, was placed in this dog's mouth shortly after death. This finding suggests the animal was according special mortuary treatment, perhaps acknowledging its role in mammoth hunting. The fossil comes from the site of Predmosti, in the Czech republic, and is about 27,000 years B.P. old. This object is one of three canid skulls from Predmosti that were identified as dogs based on analysis of their morphology. (Text: PennState Science Photo: Anthropos Museum, Brno, the Czech Republic, courtesy of Mietje Germonpre.) look at Petwatch June 2014
In the paleolithic period humans and wolves were living in same structured family associations hunting the same big mammals using very similar nonverbal communication and very similar hunting strategy as well. Due to evolutionary continuity of mammal brains mirror neuron mechanism enabled them to understand each other (Buccino 2004/ Senju 2008). This mutual empathy reduced stress and helped to become confident. Behavioral cultures between wolf and human clans were formed, individual bonding started, genetic isolation of those wolfclans began. We consider domestication is essentially an epigenetic based process of changing the activties of HPA stress axis and serotonin system.

Thus domestication process started.

Domestication means among others decreased flight distance and decreased sensory threshold chiefly concerning to humans, so we have to focus on limbic brain regions which play a key role in mood control. Sensitive to glucocorticoids and innerved by serotonergic projections the (HPA)stress axis and the serotonin system are closely cross-regulated under physiological conditions.
Epigenetics: High-nurturing mothers raise high-nurturing offspring, and low-nurturing mothers raise low-nurturing offspring. This may look like a genetic pattern, but it's not. Whether a pup grows up to be anxious or relaxed depends on the mother that raises it - not the mother that gives birth to it. © 2014 University of Utah
Reffering to Michael Meaneys work (Montreal/ McGill University) there is evidence that the activity of genes implicated in mammal brain development and function are regulated epigenetically by social environment. Social factors like licking and grooming  decrease stress levels via increased serotonin which induces hippocampal glucocorticoidreceptor expression. When cortisol interact with these hippocampal glococorticoidreceptors, they exert a negative feedback signal which inhibits synthesis of cortisol. That renders to subsequently modest stress. Hippocampal glococorticoidreceptor density and thereby the activity of the stress axis are determined epigenticly in childhood but stay variable during lifespan.
(Photo: Christoph Jung)
This epigenetical regulation effected decreased cortisol levels, cross regulated prosocial neurotransmitter activity increased, maternal care improved. Hence from generation to generation the stress level of human associated wolves decreased. That means flight distance and sensory threshold concerning to humans decreased as well. Eventually the wild wolf became a tame wolf.

But a tame wolf is not yet a dog.

High cortisol levels hinder neural structures which are important for learning. But tame wolves were used to human presence, hence epigenetic decreased cortisol levels enabled them to learn better from humans. Due to similar social behaviour and similar mirrow neuron mechanism empathy and ToM could increase amomg both specimen. Thus, the tame wolf could grow into a domesticated social dog getting able to work together with humans in an active form of partnership.

 Dogs are told to be man's best friends. But why?

Today social interaction between humans and dogs is still reducing the activity of HPA stress axis in both specimen as explained in the model of active social domestication. Reducing stress and invigorate therefore social and learning ability might be the reason of the benefit of dog facilitated therapy in medical and social treatment.
Dogs don't just substitute human partners. Communicating with dogs is mostly a non-verbal emotional based kind of communication. Mainly it is not focused on cognitive forebrain activity, but on limbic and social brain systems decreasing stress activity. Hence individual plans and intentions are not in center of communication but the social relationship itself. The meaning of dog-human bonding is not thinking and planning. The meaning of dog-human bonding is to relax and to be happy every shared moment. Being relaxed helps staying healthy and enhances learning ability.


by Daniela Pörtl and Christoph Jung