Revision summary
Smell is chemical communication through glands, urine and body odour. Strepsirrhines keep a rhinarium and vomeronasal organ and mark heavily, as in ring-tailed lemur stink fights. Callitrichids such as marmosets and tamarins mark range with glands. Haplorhine monkeys and apes rely more on vision, though some inspection behaviour remains. Functions include territory, reproductive status, kin recognition and alarm. Human pheromone claims are a separate and contested literature.
Model answer
Introduction
Among non-human primates, smell is a social signal, not a leftover sense. Chemical cues on the body and in the environment tell others who is here, who is ready to mate, and whose range this is. The channel is stronger in some lineages than in others.
Body
How the signal works
Smell travels as urine, faeces, gland secretions and whole-body odour. Many strepsirrhines (lemurs, lorises, galagos) keep a moist nose and a working vomeronasal organ (Jacobson’s organ). They are olfactory specialists. Haplorhines (tarsiers, monkeys, apes) reduced that hardware as colour vision and facial signalling expanded. This is a phylogenetic contrast, not a ladder. A lemur is not a failed monkey.
Field primatology by workers such as Alison Jolly on ring-tailed lemurs made scent-marking visible to anthropology students who otherwise notice only calls and faces.
Functions of the signal
- Territory and range: Ring-tailed lemurs (Lemur catta) mark with wrist and upper-arm glands. Males even waft marked tails in ritual “stink fights” over space and status. Marmosets and tamarins (callitrichids) use circumgenital and chest glands to label a home range, as A. F. Dixson and field studies of New World monkeys have described.
- Sex and rank: Odour can advertise oestrus, individual identity and dominance. In many strepsirrhines, chemical cues help decide who may approach whom. In catarrhine monkeys and apes the same work is done more by vision and behaviour, though residual sniffing and genital inspection still occur, for example in some macaques.
- Kin and infant: Mothers and infants recognise one another partly by smell. Nocturnal mouse lemurs and lorises lean on nest and body odour more than diurnal monkeys do.
- Alarm and spacing: A volatile cue can draw a group together or, conversely, warn that a predator or a rival troop has passed.
Comparative yield
Primate communication is multimodal. Smell is the quiet channel that human observers under-record because our own noses are weak. Strepsirrhine marking, New World glandular marking, and the haplorhine shift toward vision together define the contrast. Contested human pheromone claims belong to a different question.
Flow diagram
flowchart TD S[Scent signal] --> T[Territory] S --> X[Sex and rank] S --> K[Kin and infant] ST[Strepsirrhines] --> S H[Haplorhines] --> V[Vision-heavy]
Conclusion
- Smell among non-human primates is a full signal system with senders, receivers and contexts: territory, mating and kinship. It is richest where the vomeronasal organ and scent glands still work. Treat it as comparative primate behaviour, not as a story about human attraction.
Quick related
Students also ask
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Discuss the Miocene hominoid remains and their significance in evolution
Next question on this syllabus topic (2025 · Q2(a)). View answer →
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Do apes use smell socially?
Less as a primary channel than lemurs. Some inspection remains, but vision and gesture dominate.
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Is this the same as human pheromones?
No. The question is about non-human primate signalling. Human pheromone literature is contested and is not required here.
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