Synodic Monthly Modulation of the Diurnal Rhythm of Hamsters

Relating the 4-year lemming (Lemmus spp. and Dicrostonyx spp.) population cycle to a 3.8-year lunar cycle and ENSO

Reported peak years of lemming (Lemmus spp. and Dicrostonyx spp.) and Arctic fox (Vulpes lagopus (Linnaeus, 1758)) abundance were compiled from the literature for 12 locations spanning 127 years. The mean period of the 34 reported lemming and Arctic fox cycles from 1868 to 1994 was 3.8 years, suggesting that the period of the 4-year cycle is actually 3.8 years. Peak population years were predicted using a simple model based on a 3.8-year lunar cycle. For nearly 130 years, reported years of peak abundance of lemmings and Arctic foxes were significantly correlated with and have persistently stayed in phase with predicted peak years of abundance. Over the same period, predicted peak years of lemming abundance have been closely aligned with peak (i.e., La Niña) years of the January–March Southern Oscillation Index (SOI). From 1952 to 1995, peak flowering in Norway tended to occur close to trough June–August SOI (El Niño) years. The hypothesis proposed is that the 3.8-year lunar cycle governs the timing of the lemming cycle, but it does not cause the population cycling itself. If this hypothesis is true, then the heretofore unexplained source of the persistent periodicity and quasi-metronomic regularity of the lemming cycle is identified.

Geophysical Variables and Behavior: XLIX. Moon Mechanisms and Myths: A Critical Appraisal of Explanations of Purported Lunar Effects on Human Behavior

In this paper the explanations put forward by lunar advocates to account for a “lunar effect” on human behavior are critically appraised. The hypotheses considered are ozone, moonlight, gravity, tidal force, geomagnetism, electromagnetism, weather, ions, and ELF waves. It is concluded that none of these are sufficient to explain the alleged effects of the moon on human behavior. In view of (a) the lack of a satisfactory mechanism, (b) the lack of a reliable connection between lunar periodicities and human behavior, and (c) the generally negative results obtained in studies, it is suggested that the scientific community exercise great caution with regard to further studies claiming lunar effects on human behavior.

Moon Phase' in Behavioral Research

Although the lunation cycle (phases of the moon) has been employed in behavioral research, there is little evidence that the variable is properly understood or recorded. In reality the phases of the moon are not a property of the moon alone but rather result from the angular relationship between the sun, moon, and earth. It is argued that a suitable analysis would require that the celestial longitude of both sun and moon be recorded separately for any given event and then analyzed conjointly with respect to that event. The main effects of both the sun's and moon's position can then be assessed, and the influence of moon phase and other sun-moon relationships will emerge as statistical interactions if significant.

Leaf movements and their relationship with the lunisolar gravitational force

BACKGROUND

Observation of the diurnal ascent and descent of leaves of beans and other species, as well as experimental interventions into these movements, such as exposures to light at different times during the movement cycle, led to the concept of an endogenous 'clock' as a regulator of these oscillations. The physiological basis of leaf movement can be traced to processes that modulate cell volume in target tissues of the pulvinus and petiole. However, these elements of the leaf-movement process do not completely account for the rhythms that are generated following germination in constant light or dark conditions, or when plants are transferred to similar free-running conditions.

SCOPE

To develop a new perspective on the regulation of leaf-movement rhythms, many of the published time courses of leaf movements that provided evidence for the concept of the endogenous clock were analysed in conjunction with the contemporaneous time courses of the lunisolar tidal acceleration at the relevant experimental locations. This was made possible by application of the Etide program, which estimates, with high temporal resolution, local gravitational changes as a consequence of the diurnal variations of the lunisolar gravitational force due to the orbits and relative positions of Earth, Moon and Sun. In all cases, it was evident that a synchronism exists between the times of the turning points of both the lunisolar tide and of the leaftide when the direction of leaf movement changes. This finding of synchrony leads to the hypothesis that the lunisolar tide is a regulator of the leaftide, and that the rhythm of leaf movement is not necessarily of endogenous origin but is an expression of an exogenous lunisolar 'clock' impressed upon the leaf-movement apparatus.

CONCLUSIONS

Correlation between leaftide and Etide time courses holds for leaf movement rhythms in natural conditions of the greenhouse, in conditions of constant light or dark, under microgravity conditions of the International Space Station, and also holds for rhythms that are atypical, such as pendulum and relaxation rhythms whose periods are longer or shorter than usual. Even the apparently spontaneous short-period, small-amplitude rhythms recorded from leaves under unusual growth conditions are consistent with the hypothesis of a lunisolar zeitgeber. Two hypotheses that could account for the synchronism between leaftide and Etide, and which are based on either quantum considerations or on classical Newtonian physics, are presented and discussed.

Aggression in a prison setting as a function of lunar phases

Previous studies of the possible effects of the moon's phases upon human behavior initially yielded contradictory results and later more consistently negative results. The present study capitalized on a captive deviant sample prone to aggression, one of the earlier targeted behaviors. A Pearson correlation between number of reported incidents in a Texas prison and the amount of lunar luminosity (lunar phases) yielded no significant correlation.

Common 30-day multiple in gestation time of terrestrial placentals

Weekly, twice-monthly, and monthly lunar related rhythms have been alleged for various animal reproductive processes. Herein gestation times of 213 types of terrestrial placental mammals were analyzed for best-fit integer multiples approximating length of any of the above lunar related rhythms. At the same time numeric controls were constituted of a completely random, a block randomized, and a sequential set of numbers spanning the data set. Among test integers 6 through 33, the number 30, approximating the 29.53-day lunar-synodic month, was consistently and statistically a best-fit multiple to the data. This might suggest a once-monthly lunar illumination, but not a twice-monthly gravitational or near-weekly tidal, influence upon animal reproduction. As for a receptor mechanism, the tapetum, or reflective layer of the retina, present in most land mammals, but absent in humans, enhances dim illumination. A suggestion is that because of this visual enhancer, cycling moonlight might be a circa-lunar physiologic timer for many terrestrial mammals.

The pattern of motor activity, light, and melatonin production in Syrian hamsters

To investigate the motor rhythm of the Syrian hamster under natural photoperiod and to relate these findings to pineal rhythm, animals were left undisturbed in metabolic cages in which stabilimeter systems registered motor activity, photovoltaic cells registered light intensity, and in which urinary output was used for the assay of the major melatonin metabolite 6-sulphatoxymelatonin. The motor activity of two animals was monitored during 1 month and showed a striking similarity. Melatonin secretion was measured during 3 consecutive days and showed a night/day ratio in both animals that was relatively constant and that was coupled to the diurnal rhythm of the animals' activity.