Summary: New genetic evidence challenges the idea that humans have lost their sense of smell. A study of the Indigenous Orang Asli populations in Malaysia shows that human olfaction has been dynamically molded by culture, diet, and environment. While agricultural societies accumulated mutations that weaken certain smell receptors, hunter-gatherer groups retained more functional, ancestral versions of olfactory receptor genes that help them detect food and environmental cues in the rainforest.
Key Findings
- Olfactory vocabulary: Hunter-gatherer communities often possess rich, specific vocabularies for smells. In contrast, many people in agricultural and urban settings describe scents by analogy (for example, “it smells like a rose”), reflecting less reliance on smell in daily survival.
- Metabolic connections: Among some agricultural Orang Asli groups, notably the Jakun, a variant of the OR12D3 gene shows distinct evolution. OR12D3 has been linked to insulin metabolism, suggesting that dietary shifts toward carbohydrate-rich foods may have driven adaptive changes in genes that affect both smell and metabolic regulation.
- Subsistence-driven selection: This research provides genetic evidence that how people obtain food—hunting and foraging versus farming—exerts strong evolutionary pressure on the olfactory system.
- Not a simple loss of smell: Although humans lost a large fraction of olfactory receptor genes during earlier primate evolution, the remaining olfactory repertoire continues to undergo active, meaningful evolutionary changes tied to lifestyle and environment.
Published April 16 in the journal Cell Reports, the study examined how olfactory receptor (OR) genes vary among three Orang Asli groups on the Malay Peninsula: Negritos (hunter-gatherers), Senoi (swidden or rotational farmers), and Proto-Malay/Jakun (traditional agriculturalists). By comparing OR gene diversity in 50 Orang Asli genomes with global data, the authors uncovered clear links between subsistence mode, environment, and olfactory gene evolution.
Lead author Lian Deng of Fudan University explains that people commonly assume human smell is unimportant and has deteriorated over time. The new results counter that idea: olfaction has been continually shaped by the interplay of genes, environment, and cultural practices. Olfactory receptors remain one of the most ancient sensory gene families, and their evolution continues to reflect the selective demands of different lifestyles.
The Negrito hunter-gatherers stood out for carrying fewer damaging mutations in their OR genes and for retaining more ancestral alleles associated with strong receptor function. Compared with many global populations that show elevated OR diversity and mutation loads, Negritos displayed a conserved OR profile with lower mutation burden and less archaic introgression for many receptors. These genetic patterns suggest directional selection preserving olfactory capabilities essential for detecting edible plants, ripe fruit, and other forest cues.
Negritos were also enriched for receptors tuned to earthy, fruity, and herbal odors — scent categories that are common in rainforest habitats and important for foraging. By contrast, agriculturalist groups showed greater diversification of OR genes. Some of these changes appear to be direct chemosensory adaptations to agricultural environments, while others reflect pleiotropic effects, where OR genes influence non-olfactory physiology such as insulin regulation or lung function.
One notable example is the Jakun-specific variant of OR12D3. Prior research links this receptor family to insulin metabolism, and Deng’s team hypothesizes that the Jakun variant may represent an adaptive response to carbohydrate-rich diets associated with horticulture and farming. This example highlights how olfactory genes can play dual roles: detecting environmental chemical cues and participating in internal metabolic processes.
The study concludes that subsistence strategies exert measurable evolutionary pressure on sensory systems. By studying smell genes, researchers can trace how culture, environment, and biology coevolve. These findings emphasize that human olfaction is not simply a relic of the past but an actively evolving system shaped by local ecological and cultural demands.
Funding: 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. Research involved sustained collaboration with Malaysian institutions and received support from Malaysia’s Ministry of Higher Education and Ministry of Science, Technology and Innovation. All activities were conducted with approval from the Department of Orang Asli Development.
Key Questions Answered:
A: It’s both biological and cultural. Survival in dense forests depends on identifying specific plants and prey, so languages and daily practices emphasize precise odor distinctions. In contrast, urban and agricultural lifestyles treat smell as background, reducing the emphasis on olfactory vocabulary.
A: Genetic changes take many generations, but perceptual ability can improve. Olfactory training and focused practice can sharpen scent discrimination and awareness even if some receptor genes carry mutations.
A: Olfactory receptors are expressed beyond the nose, including in gut, liver, and pancreas. Some OR genes therefore have pleiotropic roles that influence metabolism and nutrient processing as well as scent detection.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff for clarity.
About this genetics and olfaction research news
Author: Queen Muse ([email protected])
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. 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 has been understudied. We examined olfactory receptor (OR) gene evolution in Malaysian Orang Asli groups 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 profiles characterized by lower mutation load, greater retention of ancestral alleles, and depleted archaic introgression.
Subsistence-related divergence revealed adaptive signals at ancestral haplotypes in OR12D2 (geosmin) and OR52J3–OR52E2 (butter), and enriched archaic introgression in musk- and fruity-sensing receptors (for example OR5A1/2 and OR4D6) in Negritos. Agriculturalists showed diversification involving pleiotropic targets, including OR12D3 (linked to insulin regulation) and receptors tied to pulmonary function.
These findings indicate that directional selection preserves ancestral olfactory repertoires in hunter-gatherers, while agricultural transitions drive diversification through both direct chemosensory adaptation and indirect pleiotropic pressures. Our analysis demonstrates how subsistence strategies shape sensory evolution through intertwined genetic, cultural, and environmental pathways.