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.
