It seems there exists an established yet hidden cat calling system.
asserted
It → seem → system
According to scientists, cats identify one another through a shockingly durable chemical "calling card" made from 13 unusual fatty acids in their urine.
uncertain
cats → accord → urine
Thus, feline friendships might have to do more with their identification than consistent meetings.
uncertain
friendships → have → meetings
Cats rely heavily on scent to learn about one another and often, they gather this information from urine and other odour marks left behind in their surroundings.
asserted
they → rely → surroundings
These chemical traces can continue communicating long after the animal that produced them has moved on.
asserted
that → continue → them
But this leaves us with a puzzle.
asserted
this → leave → puzzle
Many odour molecules evaporate, break down or change over time.
asserted
molecules → evaporate → time
If a scent is consistently evolving, how is an animal still able to determine who originally left it?
asserted
who → evolve → it
Researchers from Japan, Germany and Spain, led by Iwate University, may have found part of the answer in domestic cats.
uncertain
Researchers → lead → cats
Their experiments pointed to a group of unusual fatty acids that could serve as a lasting chemical signature in cat urine.
uncertain
that → point → urine
The scientists identified 13 branched-chain fatty acids (BFAs).
asserted
scientists → identify → acids
The particular mixture and proportions of these compounds varied from one cat to another, yet remained relatively consistent within the same animal.
asserted
mixture → vary → animal
Behavioural tests also showed that cats could detect differences between BFA profiles when the researchers controlled for other lipids in the urine.
uncertain
researchers → show → urine
The findings suggest that BFAs could function as a durable chemical "calling card" that helps preserve information about individual identity.
uncertain
that → suggest → identity
Cats remember individual urine scents
asserted
Cats → remember → scents
Before searching for the chemicals involved, the researchers first needed to establish that cats could distinguish between urine from different individuals.
uncertain
cats → search → individuals
When cats encountered the same urine sample repeatedly, they gradually spent less time investigating it.
asserted
they → encounter → it
But when urine from a different cat was introduced, their interest rose again, and they spent more time sniffing.
asserted
they → introduce → time
Even after gaps lasting months, cats continued to show reduced responses to previously encountered urine odours.
asserted
cats → last → odours
This pattern suggested that cats may retain long-term memories of particular urine scents.
uncertain
cats → suggest → scents
Researchers also examined the flehmen response, the characteristic open-mouthed expression often seen when cats investigate certain odours.
asserted
cats → examine → odours
Cats displayed this response more often when smelling unfamiliar urine than when smelling their own.
asserted
Cats → display → own
As the same urine was presented repeatedly, the Flehmen response decreased.
asserted
response → present → ?
But when urine from another cat was introduced, the response piqued again.
asserted
response → introduce → cat
"After confirming that cats can distinguish individual urine odours, we used the flehmen response as a clue to identify urinary molecules that may contribute to individual scent recognition," said Professor Masao Miyazaki of Iwate University, who led the research project.
uncertain
who → confirm → project
What helps cats distinguish between individual urine
Using the cats' behaviour as a guide, the scientists narrowed their search to a lipid fraction in urine containing unusual BFAs.
asserted
scientists → help → BFAs
Ultimately, they identified 13 of these compounds.
asserted
they → identify → compounds
Interestingly, each cat has a BFA profile defined by the combination and relative abundance of the different fatty acids.
asserted
cat → have → acids
Those profiles varied considerably between animals, while remaining comparatively stable when the same cats were sampled on different dates.
asserted
cats → vary → dates
Genetics also appeared to play some role.
asserted
Genetics → appear → role
Related cats generally had more similar BFA patterns, although each animal still maintained its own distinguishable profile even within the same family.
asserted
animal → have → family
The compounds also proved relatively durable.
asserted
compounds → prove → ?
Many volatile chemicals responsible for urine odour begin changing quickly once urine is deposited.
asserted
urine → begin → odour
BFAs, by contrast, are semi-volatile and evaporate more slowly.
asserted
BFAs → evaporate → contrast
In urine-soaked samples stored at 25°C, the distinctive BFA profiles associated with individual cats remained comparatively stable for at least 24 hours.
asserted
profiles → soak → hours
Cats can detect the chemical differences
The researchers then tested whether the cats themselves could actually distinguish these BFA patterns.
uncertain
cats → detect → patterns
They controlled other lipid components in the urine samples and changed only the donor-derived BFA-containing fraction.
asserted
They → control → fraction
Cats that had already become accustomed to the original sample began sniffing more again when the BFA fraction was switched.
asserted
fraction → become → sample
That behavioural change provided evidence that cats can perceive differences among individual BFA compositions.
asserted
cats → provide → compositions
The result strengthens the idea that these fatty acids may carry meaningful information about identity rather than simply being unusual chemical byproducts.
uncertain
acids → strengthen → identity
…and 11 more, not listed.
The Aporia
