Genes ‘n Roses

October 14, 2015

Richard Newcomb, Principal Investigator of the Allan Wilson Centre,
Chief Scientist at Plant and Food Research, and Professor of Evolutionary Genetics, University of Auckland.

We can theoretically detect and differentiate a trillion smells. When the human genome was decoded, there were more genes for smell than anything else.

We only have 480 active odorant receptors out of 1000 available receptors present in our genome. These provide us each with our own unique smell perception of the world around us. So when someone says that wine smells like apricots to them, it may well be because of the differences in our genes.

People are highly suggestive with wines, in particular. If you are drinking a $100 wine, or think you are, you will believe it tastes better than the $10 bottle – even if it’s the same wine. With the $100 wine, MRIs show the pleasure centres of the brain light up in anticipation. You are your own best wine critic – so enjoy that $10 bottle 🙂

Our sense of smell is most acute at about 11.30am in the morning. A hormone called gherlin is released to make you feel hungry, i.e. it gives us hunger pangs and “turns up the volume” of our sense of smell.

Generally women have a slightly better sense of smell than men. Sense of smell fades with age. Loss of sense of smell does not necessarily mean you have Alzheimers, but it can be associated with its onset, probably because of the proximity of olfaction and memory regions in the brain

Are there different preferences among different ethnic groups of humans based on genetics? No. But there are acquired cultural preferences/dislikes e.g. Japanese often don’t like the smell of mutton. Asians often prefer yellow kiwifruit with more tropical “notes” and sweetness. The yellow kiwifruit was developed specifically to cater to this preference.

Ability to smell a compound can often have a strong genetic component but whether we like it or not is more learned, cultural.

There are machines that detect constituent odorants, by separating them and measuring relative mass of molecules. This machine is slow and not miniaturised though, so we still use dogs and humans to do the sniff tests. Dogs can smell cancer, though we don’t know exactly what compounds they are smelling. Dogs have about the same number of odorant receptors as humans, but all of them are active. Bees are being trained to detect TB. Rats already can. These TB-identifying compounds have been identified. Animals (again, bees) are also used in mine detection through their sense of smell.