science

Eyes of the beholder and the beheld – The Hindu


A recent report described the remarkable prowess of a female dog in the Kaziranga National Park in Assam. She could sniff the presence of poachers of the rhinoceros and tigers and warned the forest officials about it. The officials named it Quarmy since she was equal to a quarter of an army. Likewise two dogs named Nirman and Myna sniffed the presence of tigers and their poachers in the Madhya Pradesh forests.

Keen senses

Dogs belong to the wolf family and have inherited a keen sense of smell and vision from them. Wolves have over 300 million smell receptors compared to just 6 million in humans and can smell the presence of someone 3 kilometres away. And they have sharper vision and hearing — they can hear their prey 10 km away. Dogs have inherited these senses of smell, sight and hearing. We know of how dogs sniff malaria and even cancer in humans (see earlier article on 9-12-2018). Happily enough, dogs are tamer than wolves and can be domesticated. A recent report by a team of researchers from UK and USA describes yet another feature of dogs, namely how a dog’s facial muscles have evolved over the years as they were domesticated and that their ability to raise their eyebrows resembles ours. This ability, argue the researchers, have triggered their nurturing by humans, making dogs our “best friends” (Kaminski et al., Evolution of facial muscle anatomy in dogs, PNAS,116: 14677-81,July 16, 2019).

Dogs were domesticated about 33,000 years ago. As they were domesticated by us, we started selecting and preferring those that better matched our relationships. Such selections have involved the ability of dogs that are able to read and use our communications better than other animals are not able to. As the authors point out: “dogs are more skilful in using humans communicative cues like pointing gestures or gaze direction even than human’s closest living relative chimpanzees.”

Eye contact has turned out to be an important contribution to the dog–human relationship. A Japanese group points out that mutual gaze between dogs and human leads to biochemical changes both in the owner and the pet dog, and an attachment akin to that between a mother and her infant! To quote the researchers again: “The most likely evolutionary scenario is that dog’s ancestor must have, to some extent, expressed characteristics that elicited care-giving response from humans. Humans then consciously or unconsciously favoured and therefore selected for those characteristic leading to the analogous adaptations in dogs today”.

Mutual gaze

And of these, mutual eye contact and gazing has been an important contribution. Dog owners know only too well how moving the gaze of their pet is — sometimes so sad that they need to be hugged, and some other time so upsetting that you want punish them. The UK–USA group has done particular research on how the facial muscles and the anatomy of dogs have been selectively evolved to contribute to this mutual eye contact and the “language” expressed in such gazes. We humans favour dogs that show “paedomorphic” (infant-like) features like large forehead, large eyes and so on. The team has also shown that a particular set of facial muscles make the eyebrows raise and lower, which is appealing to us humans.

In order to determine whether domestication has shaped facial muscles to facilitate dog–human communications, the researchers compared in detail the facial anatomical features of domestic dogs on the one hand and grey wolves on the other. Compared to dogs, wolves are unable to raise the inner part of their eyebrows. Also, while dogs have a muscle that pulls the eyelid towards the ear, wolves are not able to. Dogs are also able to produce eyebrow movements that are more frequent and expressive. These are what people call the “Puppy Dog” eye movements — sad, happy, don’t care, and other expressions remarkably similar to human infants. There is no such “Puppy Wolf” movement of the eyebrow. And this puppy dog movement of the facial muscle anatomy has come about thanks to selection pressure in breeding based on human preferences.

The best dog need not be the cutest or the most beautiful. It is the one that looks at you and you return. The look is mutual affection. In the California annual contest called the World’s Ugliest Dog, the winner in 2019 is “Scamp the Tramp”, one with beady eyes, no teeth, short stubby legs, and his owner Ms Yvonne Morones is justly proud of him. It is not how the dog looks, but how he ‘Puppy Looks’ at his owner and she at him. Beauty is in the eyes of the beholder and the beheld.

dbala@lvpei.org



READ SOURCE

Leave a Reply

This website uses cookies. By continuing to use this site, you accept our use of cookies.