Summary: The molecular structure of an odor largely determines whether it is perceived as pleasant or unpleasant. People from diverse cultures tend to agree on which smells they like, indicating universal principles in human olfactory perception.
Source: Karolinska Institute
New research from an international team led by scientists at Karolinska Institutet and the University of Oxford shows that the chemical structure of odor molecules predicts how pleasant those odors will be perceived—across cultures.
Published in the journal Current Biology, the study tested odor preferences in diverse human groups to determine whether smell pleasantness is mainly driven by culture, individual experience, or universal molecular features.
“We set out to find whether people worldwide perceive odors in similar ways, or whether preferences are learned through culture,” says Artin Arshamian, researcher at the Department of Clinical Neuroscience, Karolinska Institutet. “Our results indicate that culture plays a surprisingly small role.”
The researchers combined fieldwork in remote communities with laboratory-based experiments. Participants were asked to rank a set of monomolecular odorants from most to least pleasant. Despite varied environments and lifestyles, the groups showed consistent agreement about which smells are pleasant and which are not.
Analysis shows that the identity and physicochemical properties of odor molecules explain a large portion of the shared pleasantness rankings, while individual differences account for the remaining variation. Specifically, molecular structure explained approximately 41% of the variance in pleasantness ratings, personal preference explained about 54%, and cultural affiliation only about 6%.
Fieldwork with diverse communities
The research team included scientists from Karolinska Institutet, Lund University, Stockholm University, the University of Oxford, University College London, Arizona State University, Monell Chemical Senses Center, the University of Pennsylvania, Universidad San Francisco de Quito, the University of Melbourne and the National Autonomous University of Mexico. Many collaborators conduct field research with indigenous populations.
Researchers worked with nine communities that span a wide range of lifestyles and environments—four hunter-gatherer groups and five communities engaged in various forms of farming and fishing. Some of these groups have limited exposure to Western foods and household products, offering a window into odor perception less influenced by modern consumer culture.
Consistent preferences despite different odor environments
Because these communities live in distinct odorous environments—rainforest, coast, mountains and urban settings—the study captured a broad spectrum of everyday odor experiences. Participants, numbering more than two hundred across the sites, ranked odors on a pleasant-to-unpleasant scale. While individual responses varied within each community, there was clear global agreement on which odors tended to be pleasant and which were typically disliked.
“Individual preferences can reflect learning or genetic influences, but the common pattern we observe is strongly shaped by molecular features of the odorants,” says Dr. Arshamian.
Which smells were most and least liked
Among the tested molecules, vanilla emerged as the most pleasant odor overall. Ethyl butyrate—known for its peach-like aroma—ranked highly as well. At the other end of the scale, isovaleric acid was judged the least pleasant by most participants; the compound occurs naturally in some foods such as cheese and soy products and is also associated with foot odor.
Dr. Arshamian suggests an evolutionary explanation: odors that reliably signaled nutritious or safe resources may have been favored, while those associated with spoilage or harm were avoided, shaping a common basis for odor pleasantness across human populations.
“We now have evidence for universal principles in odor perception driven by molecular properties,” he adds. “The next step is to link these findings to neural responses and map how the brain represents odor pleasantness.”
Funding for the fieldwork came from the Netherlands Organization for Scientific Research (NWO), general study support was provided by the Swedish Research Council, and additional funding came from the U.S. National Institutes of Health (NIH). The researchers report no conflicts of interest.
About this olfaction research news
Author: Press Office
Source: Karolinska Institute
Contact: Press Office – Karolinska Institute
Image: The image is in the public domain
Original Research: Open access.
“The perception of odor pleasantness is shared across cultures” by Artin Arshamian, Richard C. Gerkin, Nicole Kruspe, Ewelina Wnuk, Simeon Floyd, Carolyn O’Meara, Gabriela Garrido Rodriguez, Johan N. Lundström, Joel D. Mainland, Asifa Majid. Current Biology
Abstract
The perception of odor pleasantness is shared across cultures
Highlights
- Culture contributes minimally to odor pleasantness judgments
- Individuals within the same culture show varied odor preferences
- Physicochemical properties of molecules predict odor pleasantness
- Human olfactory perception is constrained by universal principles
Summary
Human sensory systems share common anatomical foundations, yet personal experience and biology shape perception. In olfaction, the balance between universal determinants, cultural learning, and individual taste has been unclear. To investigate, researchers asked participants from nine culturally and environmentally diverse communities to rank individual odor molecules from most to least pleasant. The study found substantial global agreement: molecular identity and physicochemical properties account for a large portion of the shared rankings, individual differences account for a majority of the remaining variability, and cultural affiliation explains only a small fraction. Together, these findings indicate that human odor perception follows strong universal constraints rooted in molecular structure, while still allowing for personal variation influenced by experience and possibly genetics.