Are you a parasite?

I’m confused. What is supposed to be the definition of a parasite? When I looked it up, a parasite is defined as something that lives off, or on, something else without contributing anything in return.

Like what? Surely every living thing is a parasite as it requires some other living thing to live off. If you are at the top of the food chain, what do you give in return? How does a cow living off grass contribute anything in return? If the argument is that the cow produces dung which recycles the nutrients of the grass then I suppose the same can be said of parasites except they recycle nutrients in a slightly different way.

The more I think about it, the more unrepresentative the symbiotic model (flowers giving nectar in exchange for pollination, for example) is in the animal kingdom. The parasitic model is the dominant one. In fact most parasites are benign because they do not usually kill the host and if they do kill the host (usually by accident – the malaria parasite is a parasite on the mosquito) then it can be argued that they are recycling the nutrients for the benefit of others.

And whose benefit are we talking about? I have read some fungal parasites are so host specific that they stop any one particular ant species from dominating the ecosystem – not so good for that particular species of ant that enjoys a boom in its population but good for all the others.

So parasites, ultimately, are good for everyone. Even the malarial parasite. It has been calculated that, aside from man made exterminations and natural disasters, malaria has been responsible for the deaths of 50% of the human race since we appeared on the planet. Imagine how much bigger our population would be without it, and we are already groaning at the seams.

So the malarial parasite is doing the rest of the natural world a favour by keeping our numbers in check. For human beings are the ultimate parasite; we kill the animals that we prey on to extinction.

Once again, it is all down to your frame of reference.

Leave a Reply