Summary: The common belief that humans have “lost” their sense of smell as they evolved is being challenged by new genetic evidence. A study of Indigenous Orang Asli populations in Malaysia suggests that human olfaction has been dynamically shaped by culture and environment.
While modern agricultural societies have accumulated mutations that impair smell, hunter-gatherer groups have maintained highly functional, “ancestral” versions of olfactory genes to survive in the rainforest.
Key Findings
- Olfactory Vocabulary: The study notes that hunter-gatherers often have a vast, specific vocabulary for smells, whereas agriculturalists (like most modern city-dwellers) struggle to describe scents without comparing them to objects (e.g., “it smells like a rose”).
- Metabolic Links: In the Jakun (agriculturalists), a specific smell gene (OR12D3) was found to have evolved differently. This gene is linked to insulin metabolism, suggesting that as their diet became more carbohydrate-heavy, their “smell” genes adapted to help regulate blood sugar.
- Selection Pressure: The research provides the first genetic proof that subsistence strategies, how we get our food, exert strong evolutionary pressure on our sensory systems.
- Gene Loss Myth: While humans lost about 60% of their functional olfactory genes during the transition from primates, this study shows that the remaining 40% are still under active, high-stakes evolutionary refinement.
Source: Cell Press
From the ability to detect the smell of wet soil to the scent of ripe fruit, the human olfactory system has evolved over thousands of years in response to how people live and what they eat, according to a new genetic study of Indigenous populations in Malaysia.
Publishing April 16 in the Cell Press journal Cell Reports, a new study suggests that the human sense of smell may have played a bigger role in shaping evolution than previously thought, adapting alongside major cultural changes such as the rise of agriculture.
“People tend to think humans rely very little on our sense of smell to survive, and that it has deteriorated as we evolved and diverged from other animals,” says Lian Deng, the study’s corresponding author at Fudan University in Shanghai. “Our study suggests that our sense of smell has been shaped as a result of the interplay of genetics, environment, and behavior.”
Olfaction, or the sense of smell, is one of the most ancient sensory systems in the animal kingdom. But as humans evolved from primates, they lost more than 60% of the functional genes that code olfactory receptors, which are chemical sensors responsible for detecting odors. As a result, many think olfaction is a less crucial sensory system in humans.
Deng and her team were curious about how olfactory receptor genes have evolved in humans. Previous studies have found that populations with different subsistence lifestyles, like hunter-gathers versus agriculturalists, have different languages describing scents.
“Particularly among hunter-gatherers, they have really specific vocabulary to describe certain smells, whereas we usually describe a smell by comparing it to something else we’re familiar with, like ‘it smells like flowers,’” she says.
Deng and her team studied the genes of the Orang Asli, Indigenous peoples of the Malay Peninsula in Malaysia with diverse traditional lifestyles. The Orang Asli consist of three main groups: Negritos, the hunter-gatherers, Senoi, who largely practice rotational farming, and Proto-Malay, predominantly traditional agriculturalists.
The team analyzed the genes of 50 Orang Asli people from all three groups and compared them with genomic data from people around the world.
They found that Negritos, the hunter-gatherer group, had unusually well-preserved olfactory receptor genes. While most people around the world carry olfactory receptor genes with large numbers of mutations that likely impair gene function, the Negrito hunter-gatherers carried significantly fewer of these damaging mutations. Many Negritos also carried more ancestral versions of certain olfactory receptor genes, which might have retained stronger function.
The findings suggest there is a strong evolutionary pressure to maintain these genes among Negritos compared with other populations, likely because smell plays a crucial role in foraging and hunting.
In addition, Negritos were more likely to carry genes associated with detecting earthy, fruity, and herbal smells, scents common in rainforest environments and often associated with edible plants and ripe fruit.
Meanwhile, populations that rely more on agriculture showed greater changes in their olfactory receptor genes, possibly because some of those genes also affect other functions in the body.
For example, the Jakun people, a subgroup of Proto-Malays, are more likely to carry a version of the OR12D3 gene that is different from the other Orang Asli populations. Previous studies have linked this gene to insulin metabolism. Deng’s team suspects that the Jakuns’ unique OR12D3 gene might be related to their need to tightly regulate their glucose levels, because their lifestyle relies more on carbohydrate-rich agricultural foods.
“Our study showed that the human sense of smell has been shaped by the way people live. This is the first time we are showing this relationship on a genetic level,” Deng says. “By looking at smell genes, we can begin to see how culture, environment, and biology evolved together.”
Funding: This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, the Shanghai Science and Technology Commission Program, the Ministry of Education of China, and Fudan University.
The study was conducted through long-term and in-depth collaborations with local research institutions in Malaysia, with substantial support from the Ministry of Higher Education Malaysia and Ministry of Science, Technology and Innovation of Malaysia. All research activities were carried out with approval from the Department of Orang Asli Development.
Key Questions Answered:
A: It’s a mix of biology and culture. Because their survival depends on identifying specific plants or prey in a dense forest, their languages evolved precise words for scents. For us, smell is often “background noise,” so our vocabulary is much more limited.
A: You can’t change your genes, but you can train your brain. The study shows we have the genetic “hardware” for smell, but in agricultural/urban societies, we don’t use it for survival. “Olfactory training” can actually sharpen your ability to distinguish scents, even if your genes have some mutations.
A: Many olfactory receptors are found outside the nose, in the gut, liver, and pancreas. The study suggests that genes like OR12D3 evolved to pull double duty: sensing the environment and helping the body process the specific nutrients found in an agricultural diet.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this genetics and olfaction research news
Author: Queen Muse
Source: Cell Press
Contact: Queen Muse – Cell Press
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Gene-Culture Coevolution Shapes Olfactory Receptor Gene Diversity in Orang Asli Populations” by Yueyang Ma, Boon-Peng Hoh, Shuhua Xu, and Lian Deng. Cell Reports
DOI:10.1016/j.celrep.2026.117181
Abstract
Gene-Culture Coevolution Shapes Olfactory Receptor Gene Diversity in Orang Asli Populations
The genetic and evolutionary basis of human olfaction remains understudied. We examined olfactory receptor (OR) gene evolution in Malaysian Orang Asli with distinct subsistence modes: Negrito hunter-gatherers, Senoi swidden-agriculturalists, and Jakun horticulturalists.
Global populations generally display elevated OR diversity relative to genome-wide levels, whereas Negritos exhibit conserved OR gene profiles featured by lower mutation load, accelerated ancestral allele retention, and depleted archaic introgression.
Subsistence-related divergence revealed adaptive signals at the ancestral haplotypes in OR12D2 (geosmin) and OR52J3–OR52E2 (butter) and enriched archaic introgression in musk/fruity receptors (e.g., OR5A1/2 and OR4D6) in Negritos, whereas agriculturalists showed diversification involving pleiotropic targets, including OR12D3 (insulin regulation) and receptors tied to lung function.
These findings suggest that directional selections preserve ancestral olfactory repertoires in hunter-gatherers, while agricultural transitions drive diversification through direct chemosensory adaptation and indirect pleiotropic pressures.
Our analysis demonstrated how subsistence strategies shape sensory evolution via intertwined genetic, cultural, and environmental pathways.
