Sunday, September 11, 2011

Smell and taste

I breathe through the tracheostomy and very little air passes into my nose so I can smell an odour only if it is strong.The limen for smell would be undetectable for me. Jaya sometimes asks me whether I can smell a gas leak or the perfume in a room spray. I will have no idea about these things.I am not the best candidate on whom 'ambient scenting' techniques can be tried. I will not be good in recording an olfactory history. I can't resist writing a bit about evolution here. In Your Inner Fish, Neil Shubin writes:
Humans devote about 3 percent of our genome to odor genes, just like every other mammal. When geneticists looked at the structure of the human genes in more detail, they found a big surprise: fully three hundred of these thousand genes are rendered completely functionless by mutations that have altered their structure beyond repair. (Other mammals do use these genes.) Why have so many odor genes if so many of them are entirely useless?


Yoav Gilad and his colleagues answered this question by comparing genes among different primates. He found that primates that develop color vision tend to have large numbers of knocked-out smell genes. The conclusion is clear. We humans are part of a lineage that has traded smell for sight. We now rely on vision more than on smell, and this is reflected in our genome. In this trade-off, our sense of smell was deemphasized, and many of our olfactory genes became functionless.
In my case it is doubly true that after my stroke, I have become more reliant on my eyes and my ability to smell has diminished because of reduced air flow through my nostrils.

I don't know how much role smell plays in one's attraction towards food. Perhaps my indifference towards food is because I can't smell most of them. The ones I can smell will probably be too spicy. I don't think my taste buds have been affected. I sometimes eat a little bit of sweet semi-solids like ice-cream or custard or some soft chocolate.

A strange happening over the past couple of years has been that sometimes when feeding is given, I have an expression like that of a person who has just quaffed a glass of some particularly bitter Ayurvedic concoction. It is strange because I cannot taste feedings and I cannot smell them most of the time. Doctors are not able to say why this is happening. Maybe it is just a supratentorial problem. Since it lasts only for a few minutes at feeding time and since, like the description of the Earth in The Hitchhiker's Guide to the Galaxy, it is 'mostly harmless', we have not bothered too much about it.

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