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At Mind Matters News: Has the human sense of smell declined in recent millennia?


Researchers found that people with “ancestral” genes perceived various odors as more intense:

From these experiments, they pinpointed two new scent receptors — one that detects a synthetic musk used in fragrances and another for a compound in body odor.

Study participants had different versions of the receptor genes for musk and underarm odor, and those variations affected how they perceived the scents.

HealthDay News, “People’s sense of smell may be declining, study suggests” at UPI (February 4, 2022)

If there is a gene receptor that detects “a synthetic musk used in fragrances,” it must have got started within the last few thousand years, not hundreds of thousands of years ago. That in itself is a remarkable find. The human genome may be changing faster than evolution theory is usually thought to allow.

Humans, we are told, have about 800 receptor genes for identifying smells but they vary with the individual and about one quarter of the study participants could not smell the musk. One neuroscientist offers a thought:

“It sheds light on a long debate in human and primate evolution—the extent to which sight has tended to replace smell over the last few million years,” says Matthew Cobb of the University of Manchester and author of Smell: A Very Short Introduction, to the Guardian. “There are another 400 or so receptors to study, and the vast majority of our responses to odors remain a mystery.”

Corryn Wetzel, “Humans’ Sense of Smell May Be Worse Than Our Primate Ancestors’” at Smithsonian Magazine (February 07, 2022)

Matthew Cobb may be onto something, at least where humans are concerned: We don’t pay much attention to smells unless they are especially attractive or repulsive. We take a very different view of eyesight, noticing slight deviances from what we expect in anything we see.

One commentator points out that it’s at least possible that we don’t need our sense of smell as much as we used to. Glenn Reynolds notes that colorful physicist Richard Feynman (1918–1988) liked to do a sort of experiment as a social icebreaker, to show that our human sense of smell is better than we think… More.

Takehome: To be sure that our sense of smell has declined, we would first need to see whether concerted efforts to improve it were successful. Richard Feynman tried it.

You may also wish to read: Physicist: Migrating birds’ mysterious quantum sense is “spooky.” Birds like the European robin pack a $10,000 lock-in amplifier into a 2 micron cell. This mysterious intelligence, magnetoreception, seems essential to migration, hence, to the survival of many birds. They may even “see” Earth’s magnetic field.

In partial agreement with Polistra, given the tendency to eradicate strong odours in the past 80 years or so, young children are less exposed to a wide range of strong smells as they grow up, so their sense of smell would not develop as well as in a hunter-gatherer or middle-ages society. So it might be a simple case of use it or lose it. Moreover, since humans settled down in towns and cities, the stink of wastes (human and otherwise) was probably much worse than in smaller, nomadic groups, so losing the sense of smell may have been a blessing. This does not conflict with my first paragraph as that came much later. Fasteddious
In "advanced" western countries we've certainly been eliminating most interesting scents. Tobacco carries an extremely complex set of scents, and we've eliminated it from public places. Perfumes and hairspray and "pollution" are also complex, and we've been "disinfecting" and "cleansing" them for 50 years. It's a horrible positive feedback loop. As the sensory universe narrows, each noticeable smell becomes more salient. OCD and "multiple chemical sensitivity" can then pick out more and more "pollutants" for obliteration, pushing tirelessly toward a universe of pure theory with no matter or life. The same thing happens with immunity. As we eliminate "dirt" and germs from our life, we lose the ability to smoothly and intelligently adapt to a new germ. Our two years in torture chambers wearing ballgags has INTENTIONALLY accelerated the loss of intelligent adaptation and immunity. Sensory deprivation is a classic tool of torturers, because it makes the torturer's job cheaper and more efficient. After the victim's senses have been de-adapted, any little pain or disruption will ruin the victim. polistra

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