Comp 11 Flashcards
Why are we interested in domestication?
Because Darwin was! He wanted to understand mechanisms of variation and therefore support his hypothesis.
In 2004 Bloom said for psychologists, dogs may be the new chimpanzees.
What is domestication
It is not the same as tamed. Chimps that live as part of a human family are not domesticated, they are still in their wild form. Travis was a ‘tamed’ chimp, and as an adult pet-chimpanzee, he mauled a friend of his owner.
Dogs, cats, goats and pigs are amongst some domesticated species. With dogs being the oldest, then cats, then goats, then most recently pigs.
What is the comestication syndrome?
Changes in morphology. Changes in physiology. Changes in behaviour. Changes in cognition.
Discuss what is meant by changes in morphology
Reduced cranial capactiy.
Smaller canines and less canine dimorphism.
Dipegmentation of coat.
Discuss what is meant by changes in physiology
Muted stress.
Multiple periods of receptivity. (in the wild, females are often only fertile once a year).
Higher basal serotonin and lower corticosteroids.(serotonin increases, so does relaxedness).
Discuss what is meant by changes in behaviour
More playful.
More vocalisations.
What were the silver fox experiments
Artificial selection on a population of silver foxes. If foxes were not acting tame, they were the control group, however if they were acting tame they were bred and became more dog-like over 6 generations. After 10 generations, they had dog-like behaviours and attached to humans. They were also observed to have morphological differences.
What is paedomorphism?
Adult form is stuck in an early stage of development and seems juvenile. The hypothesis is that domesticaion syndrome is in large part a consquence of changes in development. Selection for reuced aggression tends to favour regulatory genes that affect neuroendocrine maturation. As a result, adult aggression in domesticates is reduced relative to the ancestral state. Patterns of aggression in domesticated animals, and in experimental populations selected for reduced aggression, show similarities to those found in juveniles of unselected populations.
Discuss paedomorphism and aggression
Selection for reuced aggression tends to favour regulatory genes that affect neuroendocrine maturation. As a result, adult aggression in domesticates is reduced relative to the ancestral state. Patterns of aggression in domesticated animals, and in experimental populations selected for reduced aggression, show similarities to those found in juveniles of unselected populations.
Paedomorphic aggressive responses may derive from the delayed development of physiological responsiveness in domesticated animals.
The brains of experimentally domesticate foxes and rats exhibit elevated levels of serotonin relative to unselected populations.
Serotonin levels are higher in brains of immatures than in brains of adults, and increased serotonin leads to decreased impulsive aggression, this suggests paedomorphism in the serotonergic system.
Discuss the domesticated dog
Domestication of dogs happened when humans were still hunter-gatherers, about 30,000 years ago. However, until recently we believed it to be only 12,000 years ago. We think it started in Europe and East Asia, as ancestors were Eurasian Grey Wolves, with recent evidence suggesting the ancestor is extinct.
However, there were only a few domestication events, dogs spead quickly to other areas in the world, and there are different possible scenarios for why dogs have been domesticated.
For example, hunting success may have increased with dogs, no matter if there was a small or large group of humans hunting.
What is neoteny
The same as paedomorphism, adult form is stuck in an early stage of development and seems juvenile. It is the cause of juvenile and puppy like traits.
Compared to wolves, dogs retain the puppy-like propensity to be socialised to a much greater extent at later points in their lives.
While wolves show an increase in the number and complexity of agonistic signals used in aggressive contexts throughout their lives, domestic dogs display only a few juvenile-like agonsitic signals into adulthood.
Name one key difference between wolf puppies and dog puppies in their behaviours
Dog puppies differentiate their owner from strangers, irrespective if they are pet dogs or hand-raised. However wolf puppies do not.
This was found from a study that raised puppies and wolf puppies exactly the same. Dog puppies and wolf puppies had to choose between a stranger human and a stranger dog, and the dogs choose human and the wolves choose dog.
What are paedomorphic traits?
Round faces, flat faces, big eyes - but most of these mean less healthy. For example Pugs and Cavalier King Charles dogs - larger eyes, flattened face, small nose. But it mean their brains are too big for their heads, pugs eyes often pop out of their too small sockets. Tongues don’t fit in mouth.
Its also why pugs are wrinkely.
Using FACS we can identify observable facial changes associated with underlying muscle movements.
Discuss convergent evolution
Continuities across species are used to understand evolutionary past. If certain traits exist in distantly related species we can gain valuable insights into selection pressures at work during the evolution of these traits.
Do dogs use human communication?
In comparison to apes, dogs perform much better in terms of responding to a human pointing and gazing (Brauer, Kaminski, Riedel, Call and Tomasello, 2006). However the methods used to test each species were different, therefore in 2012 they tested again using similar methods for both dogs and apes, and found that dogs could understand intention pointing better than apes, but not so much with unintentional pointing or gazing.
Discuss cognition in dogs development
Dogs are able to use pointing significantly at both 6 weeks of age, and as adults (Riedel, Schumann, Kaminski, Call and Tomasello, 2008).
This means that there has been good cognition demonstrated by domesticated dogs and puppies much more so than apes and wolves.
Discuss the genetic vs ontogenic debate.
Researchers are debating whether social cognition in domestication is genetically inherited or environmentally induced.
There has been at least two waves of evolution and domestication, as some breeds are much more closely related to wolves than others. But there is no major affect of differences in understanding social cues.
What is the by-product hypothesis
The selection against aggression alone paves the way fo social cognitive skills. So, in the fox study those dogs who were tame may also have higher social cognitive abilites. The fox puppies were very similar in their abilities as dog puppies anyway. Therefore social cognition may just be something that was already there.
Also temperament effects cognition.
What is the effect of temperament on cognition
The main regulatory component of temperament is effortful control, which equals a dominant response in favour for a subdominant response. Children high in effortful control show greater empathy and maybe pay attention to thoughts and feelings of others without becoming overwhelmed by own distress. There has been a positive correlation found between inhibitory control and development of Theory of Mind.
Is there self-domestication in humans?
Certain physical changes in humans resemble signs of domestication: reduction in size, skelatal robusticity, cranio-facial shortening, and declining tooth size.
The hypothesis suggests that individuals within a social group were killed or individuals ostracized those who were over-aggressive or despotic.
Like in domestic animals, a selection for tamer, emotional reactivity may have put our hominid ancestors in a new adaptive space within which modern human-like forms of social interaction and communication could be selected for.
What is the adaptation hypothesis?
Dogs have been specifically selected for sensitivity to human communication. It suggests that pointing overrules own knowledge. There are significant differences between normal owner and a third party in both pointing and gazing.
Communication as imperative, pointing is seen as a spatial directive. Perfect adaptation to life with humans - dogs as social tools. We can use them for herding and hunting. Of which for these jobs they need these social cognitive skills.
