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Satellite of love


Empress Michiko has a habit of gazing at the moon on New Year’s Day. How do I know? Well, here’s the poem the Empress wrote for this year’s New Year poetry reading:

Each year / I look up to verify / The moon’s position/ As I see the Emperor off / For the New Year’s ritual at dawn

There’s something romantic about making a link between your lover and a celestial body, and most likely the Empress has made it her habit to note the position of the moon at the beginning of each year for no other reason than that. But I wonder, is she looking at the moon to subconsciously gauge the mood of her husband?

It’s no coincidence that the word “lunacy” comes from the Latin word for the moon (luna). Before any ultranationalist rightwing extremists start driving their buses around the offices of The Japan Times in protest, let me quickly say that in no way am I suggesting the Emperor is a lunatic. It is simply that the superstitious, medieval link between madness and the moon has apparently been validated.

A leading police officer in Sussex, England, last month announced that he would send out extra officers on patrol when there is a full moon. Inspector Andy Parr said there is a link between the numbers of violent crimes committed, and the full moon. Moreover other studies in the United Kingdom and the United States show similar correlations between violence and the full moon. Doctors also say that more people come to their surgeries around the time of the full moon.

How can this be? It seems almost mystical that the moon can affect us in this way. Still, it’s more likely than the stars and the planets affecting our moods, which is what astrologists claim. We know the moon’s gravity is responsible for the tides — perhaps the gravitational force of the moon alters the behavior of water in our own bodies, too.

Last week, a Dutch scientist published data showing that zooplankton move in patterns that correspond to the monthly lunar cycle. But these are plankton that live deep underwater, where no moonlight has a chance of penetrating. So it is not moonlight that guides the planktonic movements. Perhaps the plankton are influenced by the moon’s gravity.

Could gravity affect the way hormones work? I’ve no idea, and no idea how the suggestion could be tested, either. However, the moon does seem to influence testosterone levels in men, or at least, the hormone varies in a way that coincides with the phases of the moon. Testosterone is known to fluctuate on a daily cycle. Levels are higher in the morning, which is why men often experience a certain sexual phenomenon on waking in the mornings — I don’t feel the need to explain this further here.

But testosterone also fluctuates on a monthly cycle. Women’s monthly variations in mood and irritability and sexual desire are well known. In contrast, men’s own hormonal moodiness has been neglected. It’s not, however, increases in testosterone that are to blame for rises in crime — rage incidents and violence are apparently more likely to occur when testosterone levels are low.

Men with high levels of testosterone, on the other hand, may be irrational. A study published last week found that men playing games designed to simulate real-life business decisions were more likely to reject low offers if they had high testosterone levels, even if they stood to make money by accepting the offers.

Terry Burnham, from Harvard University, took saliva swabs from men playing the business games, and found that those with high testosterone were less tolerant. Burnham suggests that this is because the hormone may make the men more dominant. Another recent study found that people with higher levels of testosterone were stimulated by the sight of angry faces. These people learned how to perform experimental tasks quicker than people with low levels.

It’s interesting that as well as being traditionally linked to episodes of madness — or outbreaks of werewolf behavior — the full moon is considered especially romantic. If, as seems to be the case, the moon is linked to fluctuations in hormone levels, there is another twist to the story.

In a study that looked at the hormone levels of men and women who had fallen in love in the last six months, an Italian scientist found that the testosterone levels in the men were lower, on average, than men who were either single or in long-term relationships. In contrast, testosterone levels were higher in women in love than in single women.

Incidentally, the Japanese god of the moon is called Tsukuyomi, made from the characters for “moon” and “read.” It might be worth other police forces around the world “reading the moon” when deciding how many officers need to be on patrol. And women planning a romantic assignment might also like to “read the moon.”

They face a dilemma. On one hand you could choose a date that coincides with the full moon and hope that the lower testosterone the man experiences will make him more likely to fall in love. On the other hand you have to be aware that he is also likely to be more irritable and less likely to have a strong sex drive on that day.

The second volume of Natural Selections columns translated into Japanese is published by Shinchosha. The title is “Hito wa ima mo shinka shiteru (The Evolving Human: How new biology explains your journey through life)”; price 1,500 yen.