MONTREAL - If it is true what they say about a full moon provoking deviant behaviour in human beings, then evidence of an outbreak of lunacy should be clearly discernible on the streets of Montreal Saturday night.
We should expect to see an upward spike in the number of 911 emergency calls.
And we should see a rise in the number of births in local hospital maternity wards.
Saturday night's full moon, which rises at 7:38 p.m., is going to be special - and not just because it will be the last full moon of the winter, coming on the eve of Sunday's first official day of spring. No, Saturday night's moon is going to be a supermoon, also known as a perigee moon.
A supermoon is bigger and brighter than an ordinary full moon. The reason: the moon's orbit around the earth is elliptical, not round. And so when the elliptical path passes closest to earth - as it will Saturday night - a full moon becomes 14 per cent wider and 30 per cent brighter than an average full moon. Not since 1992 has the moon passed as close to Earth as it will Saturday night.
The proposition that full moons can spark deviant behaviour in human beings is known in scholarly research as the Transylvanian hypothesis. We owe the noun lunacy, and the adjective lunatic, to this proposition, and more literally to Luna, the old Roman moon goddess.
In and around Montreal, plenty of large and small social gatherings are being organized to observe Saturday night's sky. The singles dating service Meet Market Adventures is staging a moonlight walk on Mount Royal.
The Canadian Ashram of Occult and Spiritual Sciences is organizing a special meditation session at its facility on René Lévesque Blvd.
And in the Laurentians, Ski Morin Heights and the Centre de plein-air St. Adolphe d'Howard are hosting evening snowshoeing treks.
The Transylvanian hypothesis is as old as humankind itself. However, serious study has concluded that the hypothesis is not supported by scientific evidence.
A famous study that had found murders on the rise in and around Miami, Fla., during full moons was subsequently revealed to be flawed. A British Medical Journal study that found dog bites on the rise during full moons in Britain found fewer dog bites than average during full moons in Australia.
In New York City, two major studies involving 500,000 births over two different time periods found a minor one-per-cent rise in births during full-moon periods - hardly significant.
In the mother of all studies, researchers at the University of Saskatchewan looked at 37 different studies involving full moons and human behaviour and found insufficient evidence to support the notion of a lunar effect.
And yet many people still believe in one. Why? Selective memory, say psychologists. Nurses who might correctly recall full-moon nights when their maternity wards were overwhelmed tend not to recall quite as sharply those other full-moon nights when the number of births was unremarkable or lower than average.
Glenn Wilson, a psychiatrist at King's College in London, England, has pointed out something significant about full moons: They were much more noticeable to the average person before the age of electricity than they are today.
Remarkably bright nights in the 1700s and 1800s would have brought a lot of people out into the streets and created exceptionally high incidences of social interaction between strangers.
Work a little bit of alcohol into mix, and you have a lot of potential mayhem.
Montreal police say they are not planning extra patrols Saturday night. They are not gearing up to deal with any werewolves.
But what if those Meet Market Adventures singles see a hairy guy acting a little strange up on Mount Royal?