The contours and tendencies of human smell are ever-evolving, as shown in various groups in Malaysia.
Researchers have found that some Indigenous hunter-gatherers have retained unusually intact smell genes, while farming groups carry versions that have evolved with agriculture.
That contrast reframes the human sense of smell as an actively evolving system shaped by food, environment, and daily survival demands.
A divide within DNA
Within DNA from 50 Orang Asli, Indigenous peoples of Peninsular Malaysia, the strongest divide appears between hunter-gatherers and local farming communities.
Analyzing those genomes, geneticist Lian Deng of Fudan University demonstrated that Negrito participants possessed fewer changes in smell-related genes.
In comparing 2,845 individuals from populations worldwide, those preserved gene patterns remained distinct rather than blending into broader human variation.
Because these differences align closely with how each group finds and uses food, they point to smell genes as targets of ongoing evolutionary pressure rather than passive remnants inherited from previous generations.
The case against a fading nose
Humans have lost working versions of more than 60% of our smell genes, a standing indicator that smell had become less central.
Even so, olfactory receptors, genes that detect odor molecules, can still be useful when food, danger, or water must be recognized fast.
History once claimed that human smell was fading, even though daily survival often still depended on it.
Earlier work with Malay Peninsula hunter-gatherers found that odor recognition stays sharp when daily life depends on smells.
A divide built on subsistence
Among the Orang Asli, researchers compared Negrito, forest-based hunter-gatherer communities, Senoi, groups that rotate small farming plots, and Jakun, communities reliant upon settled agriculture.
Negrito groups shower fewer harmful changes and older gene versions, suggesting natural selection retained parts of their ancestral smell toolkit.
Senoi and Jakun genomes appeared more mixed and with more alterations, which shows lives that revolved less around hunting and foraging.
Those differences make the central point harder to dismiss, because subsistence did not just change menus, it also changed sensory priorities.
Odors with evolutionary weight
Several preserved gene regions were tied to earthy, fruity, and herbal notes, while another pointed to buttery signals tied to rich foods.
Those receptors work by binding airborne molecules, then sending signals that help the brain differentiate from wet soil from ripe fruit.
That butter-related region stands out because rich odors can flag calorie-dense foods, a valuable clue to sustenance when meals are uncertain.
Rather than proving the existence of sharper noses in every case, the data shows that specific smells were maintained among forest living conditions.
A shift beyond just smell alone
Jakun participants stood out for carrying a different version of a smell-related gene that has also been tied to how the body manages blood sugar.
Insulin moves sugar from blood into cells, and carbohydrate-heavy diets reinforce that system.
When a single gene influences both smell and metabolism, it can be shaped by multiple pressures at the same time.
Agriculture may have remodeled smell genes partly through food chemistry and partly through the body’s wider needs.
Hidden functions of olfactory genes
Smell genes do not stay confined to the nose, and that broadens the story far beyond scent alone.
Some are active in skin, lungs, or immune cells, where chemical sensing can change growth, inflammation, or tissue responses.
That wider role helps explain why agricultural groups showed diversification even when a gene’s main fame comes from smell.
Once smell receptors intersect with metabolism or immunity, cultural change can reshape them without changing odor use alone.
Fragments from who came before
Most ancient Neanderthal and Denisovan DNA has been stripped out of human smell genes over time.
Yet the team found pockets of archaic introgression and inherited DNA from ancient human relatives in some Bateq smell-gene regions.
One cluster involved receptors tied to musk, floral, and fruity cues, exactly the kinds of signals used when foraging.
Because most ancient variants disappeared while a few remained, the picture looks selective rather than random.
The interweave of culture and biology
One account of the work captured Deng’s plain conclusion that smell changed with the way people lived.
“Our study showed that the human sense of smell has been shaped by the way people live,” said Deng.
Deng continued by explaining that studying smell genes reveals how culture, environment, and biology have evolved together.
Instead of treating culture as a thin layer over biology, the results show each one can help shape the other.
Gaps in the genetic story
Patterns emerge from a modest sample, but they cannot prove exactly how any person smelled a fruit, fungus, or trail.
Odor perception depends on many receptors and the several brain circuits that combine them, not dependent on one gene alone.
Isolation also muddies the picture, because small populations can preserve unusual variants through chance as well as selection.
Future experiments will determine what these variants actually detect, along with long-read DNA sequencing that captures long stretches of genetic material.
A living sensory system
Human smell did not simply fade as farming increased, it kept evolving with food sources, landscapes, and body chemistry.
That makes the nose a sharper witness to human history than many people assumed, while leaving room for bigger and deeper tests in the future.
The study is published in the journal Cell Reports.
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