Are Domestic Pets Parasites?

 by Felix Roth

(image: Wiki Commons)

60 percent of households in the United Kingdom warmly embrace a domestic pet as part of their family with most pets being cats and dogs. The symbiotic relationship between us and our furry friends is sublime, unwavering and irrefutable. Nevertheless on occasion we are caught out when gazing upon this animal that was once a wolf in the arctic circle or a lion on the savannah, reduced to a being whose life is entirely dependent on our ability to open a can of dog food. At this point many of us return to our lives allowing the question of their existence to be nothing more than trivia. I however may have a line of thought that allows us to begin to unravel their existence, behaviour and the mercurial attributes that makes the domestic pet so irresistible to people the world over. 

Mitochondria, a cuckoo bird and a 30 foot tape worm. Connection? They are all cellular formations containing genes that code for a phenotype that exhibits parasitic behaviour. They are all parasites. The word parasite conjures up images of the intestinal tape worms, a tick half the size of a ping pong ball and images that illicit general feelings of sickness. I would argue that domestic pets exhibit the same parasitic features as the organisms listed above and would go so far as to say that they are such effective parasites they trick us into not even recognising them as such. 

For nearly all of this argument I will look at domestic cats and dogs as they are the most domesticated and widely recognised pet. 

A parasite is defined as “an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other's expense”. Both dogs and cats tick both boxes of the definition. They live around/on us and benefit from our expenses such as walks and food. This definition is limited however because a baby would also be parasitic using this definition. The subtlety of parasitism in pets is the behaviour that they exhibit in order to elicit a desired response from us by using a mechanism already present in the organism. Richard Dawkins explores the topic of cuckoo birds in The Selfish Gene stating that the cuckoo bird is able to infiltrate another nest because a rejection of the egg by the nest mother would mean risking losing her own egg, so she accepts the responsibility of the cuckoo in order to not risk destroying her own egg for the sake of identifying an imposter. 

Babies' behaviour acts on the autonomic nervous system of a mother eliciting a response of lactation or care for the baby. Many have hypothesised that cats act in the same way with their meow eliciting a response akin to that of the response when babies cry. Few have gone onto declare this as an example of parasitism however the similarities with brood parasitism in cuckoo birds is too similar to ignore. Like the cuckoo bird, the cat exhibits a certain behaviour to gain a response. In the cuckoos case it is simply being present in the nest that is the behaviour. Both the human and mother bird’s autonomic nervous system respond with the desired behaviour as they risk neglecting their own child if the meow or presence is ignored. In essence, the entirety of their parasitism is based around gaining a desired response from the host using behaviour that already elicits a response. Viruses can be identified to work in the same way but at a microscopic level. Cells replicate and divide readily and the virus takes advantage of this, penetrating the nucleus and asking the nucleus “ whilst you're using the printer, could you print 500 copies of me”. The mother is always going to lactate and provide care if it hears a loud pitch whine as she risks the death of the baby if she doesn’t tend to it. The cat exhibits parasitism as it mimics the cry through a meow acting on the autonomic nervous system in order to elicit a response similar to a mother tending to a baby. One could even go so far as to look at the stereotype of the spinster who fills the lack of children and a marriage with a dozen cats. The cats act on her nervous system meant for child bearing so she sees them as a like for like replacement. In reality they can be considered nothing more than parasites. 

An argument that could possibly deconstruct the meow as a behaviour of parasitism is cat’s natural tendency to meow as a kitten. I still uphold the view that a meow is an example of parasitism as the tendency to meow to other cat disappears after reaching sexual maturity but meowing directed at humans is still present. Therefore the tendency to meow as an adult can be viewed as a parasitic behaviour as the cat looks to gain a desired response from its host. Nearly everyone enjoys the apparent companionship of their cats and dogs. I am by no means getting rid of my dog or intend to show any less affection to him after writing this article. I believe they exhibit such effective parasitic behaviour that getting rid of them is nearly impossible even after the realisation that they exhibit parasitic behaviour. Domestic pets exhibit a multitude of behaviours that can be identified as parasitic however the case of the meow is a fine start to this line of thinking and could be the first in solving the case of why domestic pets are so irresistible.