Lecture 20 Flashcards
Is taming the same as domestication?
No, they are in no way the same. Domestication occurs over many generations, causing an actual change in temperament. For example, dogs, cats, goats and pigs.
Discuss the domestication syndrome
This is when an animal’s morphology, physiology, behaviour and cognition changes as a result of being domesticated by humans.
The changes in morphology usually involve a reduction of one’s cranial capacity, smaller canines and the dipigmentation of one’s coat.
Changes in physiology involve reduced stress, multiple periods of receptivity each year, higher levels of base serotonin and lower levels of corticosteroids.
Changes in behaviour involve increased play and increased vocalisations.
In terms of cognition, it is not fully known how this is affected but it is theorised that it is impacted somewhat.
Discuss the Silver Fox experiments
Belyaev artificially selected against foxes at a fur farm who were aggressive or fearful. This happened over 35 generations. After 6 generations, the foxes wagged their tails and whined more. After 10 generations, they had dog like behaviour and became attached to humans. The domesticated foxes also had floppy ears, curly tails and dipigmentation in parts of their fur, particularly on the forehead. It is said that once dipigmentation occurs, the domestication syndrome is in full effect. This was also repeated in rats, both of which found higher levels of serotonin.
Discuss paedomorphism
This is a result of domestication. Domestication changes an animals development as the selection for reduced aggression tends to favour regulatory genes that affect neuroendocrine maturation. This causes delay of maturation, which means that they become more alike to wild juveniles of that species, instead of being like adults. The high serotonin levels are similar to juveniles’ levels and it is believed that this causes the reduced aggression.
Discuss the domestication of dogs
The ancestor of dog is extinct now; Canis Lupus. It used to be thought that the domestication of dogs occurred around 12 thousand years ago as a human was found buried with a dog. However, since, it has been thought that we domesticated dogs around 30 thousand years ago as dog bones were found in a hut which were distinctly different from the wild wolves at the time. They believe that the dogs were used to help humans with hunting as studies have found that dogs improve hunting success.
In comparison to wolves, dogs remain a puppy-like propensity. Although dogs remain somewhat puppy-like, they only carry a few juvenile agnostic behaviours (fighting behaviours) into adulthood. Dog puppies can differentiate their owner from stranger, shown through play behaviour, whereas wolf puppies do not do this. It was also found that the dogs attached to their owners, unlike the wolf puppies. Side note: it has also been found that cats do not attach to their owners. When the wolves were given the option to go to a human stranger or a dog stranger, they picked the dog, whereas the dog puppies went up to the human stranger.
Although humans have selected against aggression, we have also selected for neonatal features. For example, a round flat face with big eyes. The issue with this is that it can cause problems for the dogs. Pugs can have their eyes pop out if they play vigourously as we have selected for them to have shortened bones around their eyes to make them look bigger. Furthermore, King Charles Spaniels get a lot of headaches and neurological issues as we have selected for their skull to reduce in size to make their eyes look bigger, but this means that the brain does not have enough room. Another issue is that the soft tissue does not follow this evolution, which means that their tongues are too large and they have breathing problems. We have also selected for baby-like facial characteristics as dogs who raise their eyebrows more (makes them look more neonatal) are adopted quicker. It also makes them look more sad, meaning we are more inclined to adopt them.
Discuss the convergent evolution of dogs and humans
It has been found that dogs respond to human communication such as pointing and gazing more so than chimps do, even though chimps are evolutionarily closer. It was then thought that the methods used here were too different, so an accurate comparison could not be made. A follow up study was then done with similar methodology and found that chimps did not respond to humans appropriately above the level of chance unlike dogs. Dogs are also flexible in their understanding of our non-verbal communication as they can still respond appropriately when different types of pointing were used by humans, like pointing with a stick. Furthermore, it wasn’t just about the gesture itself because if the gesture was done unintentionally, then the dogs did not respond as much compared to intentional pointing and gazing.
Furthermore, when comparing wolves raised by humans to dogs, they weren’t as good as dogs were at responding to human social communication and by 6 weeks, dogs were able choose correctly based on the human’s social communication. However, it might not be dogs using the behaviour as an informational cue, they might see it as a command. This was supported with research, as humans pointing overruled the dog’s own knowledge. Thus, supporting the idea that dogs were used as social tools to help with hunting as they were told what to hunt via human behaviour. This can be seen with herding and hunting today.
Discuss the 2 waves of domestication and social cognition in dogs
There are 2 types; dogs that are still wolf like (german shepherds for example) and dogs that are infant like. However, all of them respond well to human social communication. It is believed that this advanced skill of social cognition is a by-product of selecting against aggression; the by-product hypothesis. This was tested on foxes again and it was found that after domestication, the foxes also responded well to human social communication, unlike the wild foxes, thus supporting the by-product hypothesis. Again, it was also found with goats as well. Furthermore, it has been found that temperament affects social cognition in humans so it is possible that this also occurs with dogs. In contrast to the by-product hypothesis, the adaptation hypothesis claims that dogs were domesticated because they responded to well human communication rather than the other way round.
Discuss the self domestication of humans
It has been found that over years, humans have reduced in size, had cranio-facial shortening and had declining tooth size. This may be because the aggressive members of the group were ostracised or killed.
Discuss general social cognitive skills dogs have
They are very good at attention reading and use it for cues. For example, if your eyes are closed then they fail to understand your communication a lot more. It is also suggested that they can perspective take as they choose the toy that they think you can see, thus understanding that we could be seeing something different to them. However, other than using communicative cues really effectively, there are no special social cognitive skills found in dogs compared to other species.
Discuss Larson’s study
They compared archeological dogs to the geographic locations of 14 breeds ancient dogs (define by their genetic differentiation to other dog breeds). It was found that the locations did not correlate to where archeological dogs have been found. Furthermore, 3 of the breeds were found in locations that were outside of where canis lupus used to live. Therefore, it is claimed that these dogs are not ancient breeds, they just did not mix with other breeds as a result of cultural and geographic isolation. Thus, it becomes clear that the dog origins are still unknown, preventing us from truly understand the whole dog domestication process.
Discuss Axelsson’s study
They argue that a crucial stage of the early domestication process was that dogs adapted to thrive off of diets that were rich in starch. It was found that 10 genes associated with starch digestion that were different in dogs than in wolves, showing how they may have developed this adaptation to successfully live alongside humans with diets rich in starch. They also found 8 genomic regions associated with neural pathways were different, which could potentially explain differences in dog behaviour compared to wolves.
Discuss Sodhi’s study
They gave an unsolvable puzzle to beagles where they could easily get the first two treats but the last one was impossible to get. It was found that when they got to the last treat, they went to a human companion for help, shown via eye contact, proximity and physical contact. This shows that dogs heavily rely on humans for help and look at them as a guardian. Furthermore, the time taken to initiate contact with humans correlated to their genetics. The genes that differentiated, were genes in regions associated with behavioural disorders such as autism, bipolar and schizophrenia so dogs could be useful model to map human social disorders.
Discuss Drake’s study
They did a 3-D morphometric analysis on the skulls found and associated to be the first signs of dogs. However, they found the morphology of the skulls signified that it was a wolf skull and definitively was not a dog skull. Thus, it cannot be argued that dog domestication occurred around the time of this archeological finding.
