A large sunspot, that is, a dark area on the surface of the Sun, was observed at the time of Charlemagne's death in 813. Astronomers of the royal court causally linked these phenomena in their writings. It was not completely clear to them whether the Sun was paying tribute to the great man or whether the sunspot had affected him. Since all living things are influenced by the Sun directly or indirectly, we are not surprised to find that human time structures reflect low-frequency nonphotic, solar rhythms. It is surprising to us, however, that the apparently unsensed Schwabe cycle of solar storms is as prominently reflected in biological time structures of a population of more than a million Dutch women and a single longitudinally monitored man, as are the usually obvious and keenly sensed photic solar fluency and day/night length changes that directly transmit annual time cues to virtually every non-equatorial life-form and circadian time cues to almost all life-forms. If, and how, the solar magnetic storms responsible for these sunspot signals are apparently transmitted to living things is not clear. Plausible biophysical pathways include UV irradiation, solar protons, heavy charged particles, geomagnetic storm-induced gravitational field changes, fluctuations, and resonance signals.
We do know, however, that these solar phenomena perturb geomagnetic fields, and we know that the paramagnetic element, iron, is present in all living cells. There has been speculation about such biological sensing mechanisms for several decades (Brown et al., 1955
; Brown, 1976
). Recent groundbreaking studies have demonstrated molecular mechanisms by which fruit flies orient themselves within and respond to magnetic fields. This mechanism employs a Drosophila
light-sensitive, phylogenetically conserved, core circadian clock gene component, Cry
(cryptochrome), which, in the presence of light, is essential to transduction of magnetic field information (Ritz et al., 2000
; Gegear et al., 2008
). Electro-sensitive saltwater fish may alternatively sense fields through electromagnetic induction, while other migrating animals employ chemical magneto-reception, either through magnetite-containing organelles or magnetite-linked chemical reactions (Leask, 1977
; Kirschvink and Gould, 1981
Population biologists have reported other 10–12 year rhythms, including approximately 10-year rhythms in birth and death statistics (Halberg et al., 2000
). Physiologic measurements such as heart rate, BP, temperature, and respiration have documented various low-frequency temporal patterns (Maruta et al., 1987
; Sothern et al., 1993
; Weydahl et al., 2002
; Cornélissen et al., 2010a
). Multi-year rhythms in the waxing and waning of infectious epidemics are the rule rather than the exception (Davis and Lowell, 2006
). These are usually explained by pathogen/population feedback interactions and have generally not been adequately examined for possible links to Sun-based nonphotic geomagnetic perturbations (Hrushesky et al., 2005
). Peaks in solar radiation associated with the 10–11 year solar cycle have been implicated as a possible cause for genetic disruption of all life by means of direct mutation and immunologic stress, since even the resultant 1–2% increase in UV radiation at ground level during sunspot cycle peaks is a significant stress to an organism's DNA repair mechanisms and can, thereby, be a modulator of disease (Davis and Lowell, 2006
). A temporal association between infra-annual cycles in heliogeophysical activity and the rate of skin malignant melanoma in Europe and North America has been observed (Dimitrov et al., 2008
). Birth-dependent cancer mortality on three continents spanning 180 years has also been linked to a 17-year oscillation, a so-called sunspot double cycle, in cosmic radiation (Juckett, 2009
There are medical implications to these observed time structures. There is the possibility that Pap smear screening specificity and sensitivity for both malignant and infectious diseases is predictably greater or lesser during particular solar cycle stages, and this should be considered. If these findings are relevant to individual women, the timing of a screening Pap smear within these solar cycles may contribute to whether an abnormality is discovered. The subsequent timing within these cycles of follow-up Pap smears may then also contribute to whether the previously discovered abnormality apparently resolves or progresses. Since BP, peak respiratory flow, and other physiologic functions may also normally vary rhythmically during these nonphotic solar cycles, periodic reevaluation of the need for, and dosage of, anti-hypertensive agents and anti-bronchospastic medication should also be considered.
By what mechanisms might the observed pattern in sunspot activity be linked to changes in health status? Increases in sunspots are accompanied by changes in the amount of light and a range of other types of radiation that reach Earth, as well as changes in weather patterns, all of which, due to complex causal chains of various lengths, complexity, and duration, might affect the physiology of the individual as reflected in vital signs and the balance between microorganisms or precancer and endogenous protective mechanisms. A periodic disturbance of this balance might be reflected by the appearance of certain cervical epithelial cellular changes associated with infection and malignancy and by changes in pulmonary and cardiovascular function. Sunspot patterns affect weather patterns, and weather has behavioral, biological, and medical effects. Weather patterns and resulting patterns of prevailing global winds and currents also affect the global spread of many microorganisms. It is conceivable that solar storm–induced weather cycles could cyclically impact both human physiology and the likelihood of human infection, such as approximately 11-year Schwabe cycle–associated influenza pandemics (Hayes, 2010
Increased solar fluency that accompanies sunspot peaks increases light exposure of Earth's population of living organisms. Light, per se,
has behavorial, endocrinologic, immunologic, and physiologic effects in living things, including human beings. For example, as a population phenomenon, a study of more than 320,000 citizens over a 29-year period found that those born near peaks of solar cycles lived an average of 1.5 years less
than those born in non-peak years; the authors concluded that this must involve radiant energy, probably UV light (Lowell and Davis, 2008
). It is possible that population light exposure changes could contribute to the physiologic and pathophysiologic rhythms we have observed. Light, for instance, modulates daytime vitamin D levels and nighttime melatonin levels, each of which inversely affects the host-cancer balance (Grant, 2002
; Schernhammer and Hankinson, 2005
). Increases in radiation load during regular temporal spans of low geomagnetic protection and high flux of energetic particles increases the risk of DNA damage in living things, including human cells, bacteria, and viruses. Because the chain of events between radiation exposure and observed outcome may be protracted and of variable duration and complexity, the population hit may apparently be “out of sync” with the observed effect. The various observed lags between peak population exposure and observed outcomes means that the mechanistic chain differs from one exposure outcome pair to the next.
Consideration of possible causality is reasonable. Causality in living systems is, however, complex and time dependent. The study of biological rhythms that originate in the near Cosmos and are set and reset by rhythmic relationships of Earth's surface and the Sun have prepared researchers for the possibility that additional solar periodicities might also cause biological effects (Cornélissen et al., 2010b
; Halberg et al., 2010
). The study of the complex multifrequency time structure of biological systems has, however, conferred upon us a complex and nuanced understanding of the nature of cause and effect. Complex systems responsible for human heart rate or the balance between infectious agents and infection or cancer in the cervical epithelium are tuned by many causes, and each of these causes has many complementary effects. Different causes are more or less important in the chain at different phases of the relevant cycles (circadian, menstrual, seasonal, Schwabe). A clear causal sequence at one phase may be irrelevant to a specific effect at a different cycle phase. Most simple, uniform “constant” cause and effect relationships, that is, “reactive homeostasis,
” are oversimplified cases or artifacts of experimental paradigms constructed specifically to force the living system to behave and appear constant. The complexity and cycle stage dependency of cause and effect relationships, that is, “predictive homeostasis
” (Moore-Ede, 1986
), in no way diminishes the reality, importance, or relevance of these relationships.
It is, nonetheless, important to freely admit that, although solar activity may have the same temporal pattern as these human time structures, a causal connection may not exist. Relevant interventional, mechanism-defining experiments across several 10–11 year solar cycles that could settle this argument are hard to imagine and would be difficult to carry out, although analysis of pre-existing databases may give further clues as to the extent of the influence of environmental nonphotic cycles on additional aspects of health and disease. These circadecadal and circahemidecadal solar, physiologic, and pathophysiologic rhythms may indicate something potentially important about the physiologic and biomedical implications of our geomagnetic relationships with the internal dynamics of our Sun. Such information, if understood, could, in principle, result in better forecasting models of incidence trends and the understanding of disease etiology. The optimal timing of disease-specific screening, diagnosis, treatment, and prevention strategies within these long and predictable biological cycles holds potential benefit at no cost and without risk (Halberg et al., 2009
). Ignoring biological time structures, on the other hand, may continue to increase unnecessary risk and cost. Penultimately, were causality to be established, the possibility of developing effective magnetic prevention strategies and therapeutics becomes potentially real.
Finally, special implications to the astrobiological and space travel communities exist within these data. Energetic particles pose not only an important problem for terrestrial life when sudden coronal events and depleted geomagnetic protection coincide, but may also be a major constraining factor in planning long-range missions beyond low earth orbit. The diverse scientific community that comprises astrobiology has the necessary mix of talent in physics, radiation physics, geomagnitism, geochemistry, paleontology, and the molecular biology of unicellular and multicellular life in extreme environments with which to begin to untangle the multiple variables embedded in multidecadal environmental data sets, such as those considered in this report. We herein make available to this unique scientific community two data sets that were obtained as part of both individual perseverance and organized compulsive record-keeping across a time span far longer than the usual 3–5 year event horizon of most funding agencies. We make these data freely available to everyone in the hope of contributing to future “data mining” work from multiple disciplines that is beyond our current capabilities. In addition, the entire >4 decade–long (from 1967 to present) original self-measured data series is available online for such scholarly purposes upon request to the second author (R.B.S.) at firstname.lastname@example.org.