Tuesday, October 17, 2017

Mutation in Media Res

Alex Grey

Neanderthals didn't give us red hair but they certainly changed the way we sleep
Oct 2017, phys.org

Just thinking here about the intersection of genes and culture and their effects on our olfactory world.

This article mentions that one of the differences between people with lots of Neanderthal genes (Caucasians and to a lesser extent Asians) and people without so many Neanderthal genes (Africans) is that the Africans have a distaste for pork. I'm not an expert here, please note. But I do recall a variation on a gene that codes for pork, making male boar taste like piss to some folks but sweet to others. There's another one, not related to cavemen (as far as I know), that makes cilantro taste like soap to some people and yet a delicious herb to others.

The fact that these examples even appear in the news is because taste is far more conspicuous than smell (despite the fact that most of what we taste is actually smell). But these examples of varying genes for coding sensory perception are at least a good reminder of the fact that our sense of smell is proof that we are still evolving.

Two percent of our genome is devoted to smell - of our 10,000 genes, 250 are for smelling. The way genes work is complex, and simple arithmetic is no way to measure it, and 2% might not even sound like a lot, but still - these 250 smelling-genes are the largest of all the gene families. What's more, many of these genes have variations, called alleles, like hair varying from black to brown to red to blonde. That means the way something smells to you may differ from that of other people.

While listening to a talk on this stuff given by a smell Nobel, Richard Axel, I discovered that the gene, or genes, that code for some of the aroma compounds in broccoli have variations. That means some people taste the bad part of broccoli more than others, or that some people taste the good part more than others. Bottom line is that broccoli is not the same for everyone. And this goes for lots of things.

As far as we know, there is no allele on the genes that we use for vision. We have three photoreceptors, controlled by 3 genes (again I'm not an expert, maybe it's more complicated than this). We agree on colors, which is to say that we all see the same colors in the same way. This means that we are done evolving in regards to color (yes?). But when you see this many [olfactory] mutations occuring throughout the population, well, it means that we are still in the process of evolving. We aren't growing extra toes, or losing tails, but we are still going through the process.

Back in the day, part of this process involved a Homo Sapien seducing a Neanderthal, and making mutant cross-species babies. Before that, it meant walking on the ground instead of swinging in the trees. Today, I think we would have no idea what is really steering our species in one direction or another, but the fact that we all have such a variety of different smelling-genomes is proof that it's still happening. 


Scents and Sensibility: Representations of the Olfactory World in the Brain
Richard Axel, Columbia University, 2015

Related Links:

Human Evolution in Action

From Network Address:

Milk Does a Body, 2017

FurFuryl Mercapton, Abstract Foods, and Flavor Networks, 2012

Seeing Red, 2013

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