Professor Ernest Naylor dismisses the mythology surrounding the Moon's influence, but shows the remarkable effects that it has on our lives.

Engraved map of the celestial hemispheres by the Venetian Pietro Scattaglia from the late 18th century at Oxford's Museum of the History of Science 

Above: Engraved map of the celestial hemispheres by the Venetian Pietro Scattaglia from the late 18th century at Oxford's Museum of the History of Science

by Ernest Naylor

From early history the Moon has influenced human culture. Particular moon phases were once considered beneficial for diverse aspects of human life - from hair growth to optimal times for political meetings.

Legends and myths are manifold and some of the mythology lingers even today at Halloween, for example, with its imagery of witches, wolves and bats in silhouette against a lunar face. Timed to All Saints Eve, Halloween is a solar calendar event that causes particular excitement when it coincides with a night of Full Moon, a conjunction that occurs typically every nineteen years, determined by the Metonic cycle of coincidence of solar and lunar cycles. But are all Moon-related phenomena in humans and elsewhere in the living world as mythological as they seem? 

Above: The Oxford skyline lit by a full moon
Throughout the twentieth century the new science of Chronobiology was established and developed, based upon observations that plants, animals and humans kept in isolation were able to persist with rhythmic patterns of behaviour approximately in phase with the cyclical environment from which they were removed. The concepts of “biological clocks” and “circadian rhythms” were developed and quickly brought into the public domain, not least among airline travellers subject to jet-lag. It was established that most living organisms, including humans, carry within their genetic make-up molecular mechanisms that fairly closely match solar day timing. 
Above: Engraving of the Moon or 'Lunar Planisphere', by John Russell, portrait painter and astronomer, in 1806
Only more recently is it becoming apparent that similar molecular mechanisms are being discovered that match the timing of lunar cycles, either indirectly under the influence of Moon-driven ocean tides or directly through the influence of moonlight.  Based upon evidence that tide-related behaviour can be re-set by exposure to artificial tides in a wide range of marine species, and that in some other organisms Moon-related behaviour can be re-phased by artificial moonlight, so-called “enigmatic” biological rhythms of tidal and lunar periodicity are being brought into the mainstream of Chronobiology. 


Indeed, some biological phenomena have been well documented that even reflect adaptation to the interaction of solar and lunar events in the Metonic cycle. Some marine worms and birds in tropical localities, where seasonal changes in day-length are minimal, show remarkable timing in their breeding behaviour reflecting the change of lunar phase in relation to the solar calendar. Palolo worms off the Samoan Islands spawn at any time during a six-week period in October and November, phased to a night of the third quarter of the Moon, which of course varies in its timing from year to year.

Similarly, Sooty Terns (above) returning to breed on Ascension Island in mid-Atlantic do so within a day or two of every tenth Full Moon, thus appearing to breed at random times throughout a calendar year. Observational and experimental evidence is building up quite strongly to suggest that “circatidal” and “circalunar” clockwork can now be added to that of circadian timing within  genomes of living organisms. If that is so then the possibility cannot be excluded that circatidal and circalunar genes, like those of circadian periodicity, also occur in the human genome.

If Moon-related genes, like Sun-related genes are in the human genome they may not explain human behaviours associated with Halloween, which are no doubt based on myth and legend, but they may help to explain recent discoveries which, if confirmed, suggest that cycles of moonlight affect the sleep patterns of volunteers in a sleep laboratory. Without seeing the Moon the volunteers consistently fell asleep more quickly during nights of new Moon. 

So, if not Halloween, some of the folklore associated with lunar cycles may yet require scientific investigation if the periodicity of the Moon, like that of the Sun, is embedded in our genes

Engraving of the Annular Solar Eclipse of 1 April, 1764, by Joseph Betts, engraved by Cole, Oxford, c. 1764   Made by John Betts of University College Oxford,

Above: Engraving of the 'Annular Solar Eclipse of 1 April, 1764' by Joseph Betts of University College Oxford

Ernest Naylor is Professor Emeritus at the School of Ocean Sciences at Bangor University. His book 'Moonstruck' is out with Oxford University Press.

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By John Critchlow

My keen gardening neighbours in SW France plant root vegetable crops like carrots at a different phase of the moon from shoot crops like beans. Is there any empirical evidence to support or contradict this practice?

By Michael Bevington

The moon's biological effects at full moon and new moon seem slightly different. There may be evidence for these effects arising from the moon's disturbance of the magnetosphere, thus changing the electromagnetic magnetotail plasma sheet and the lunar wake, giving rise to biological effects on Earth - see "Lunar biological effects and the magnetosphere" in Pathophysiology, Sept. 2015 -

By max enock

Interesting. Read on moon influence

By Mike Harriss

When we lived in Canada, we learned that the time of full moon was associated with significantly more births. It was not restricted to any particular part of the country or ethnic group, and was an effect pronounced enough for hard-nosed hospital managers to adjust shift patterns so as to provide the extra cover needed.