91av

THE debate over whether pheromones influence our behaviour has been fired up
by the discovery of what may be a working gene for a pheromone receptor.

While pheromones are common in insects and lower mammals, which use them for
everything from attracting mates to marking trails, whether such chemical
signals affect humans has long been contentious. Now Peter Mombaerts of
Rockefeller University in New York and his colleagues have found eight DNA
sequences in humans that are similar to genes for mouse or rat pheromone
receptors.

The prevailing theory is that any pheromone receptor genes in humans will be
defective relics of a time when our distant forebears used pheromones. Indeed,
seven of the genes the researchers came across were flawed.

But an eighth gene, V1RL1, has no such defects and could produce a
protein similar to a rodent pheromone receptor. “We believe it’s a counterpart,”
says Mombaerts. “It has several of the hallmarks.”

When the researchers examined a wide variety of human tissues and organs,
they found V1RL1 messenger RNA in the lining of the nasal cavity, which
strongly suggests that the protein is made there. And when they looked at 11
individuals from different ethnic backgrounds, they found they all had the gene.
They are now trying to clinch their theory by proving that the protein is
present in neurons.

“It’s a pivotal paper,” says Charles Wysocki of the Monell Chemical Senses
Center in Philadelphia. “It opens some fantastic doors.”

But a few essential questions still need answering, he says. For example, are
the rodent receptors on which Mombaerts’ team based its search restricted to the
vomeronasal organ (VNO) that detects pheromones? If not, the rodent
receptors—and by implication the human one—might do something other
than detect pheromones.

Exactly how we might detect pheromones is still open to question. While
humans seem to have a similar structure to rodents’ VNO early in life, there’s
no evidence that it’s functional
(91av, 25 January 1997, p 36).
However, like rabbits and pigs, people might detect pheromones through the
main olfactory system.

Even if people do turn out to have a pheromone receptor, don’t go rushing out
to buy the perfumes that supposedly contain sex pheromones. While Martha
McClintock of the University of Chicago showed in 1998 that menstruation can be
synchronised by pheromones, there’s little other evidence of pheromonal
communication between people. And even Mombaerts believes there are few active
pheromone receptor genes in humans. “This could very well be the only one,” he
says.