Solar cycles and their relationship to human disease and adaptability

Summary

In this paper, we show that 11-year solar cycle peaks predispose humans to disease, but also endow creativity and adaptability. We give several examples of diseases that are modulated by light and present evidence for an effect of intensity and variation in sunlight, primarily ultraviolet radiation (UVR), on the human genome. The birth dates of nearly 237,000 unique clients in the Maine Medicaid database collected from 1995 to 2004, inclusive, were related to solar cycle irradiance for the past seventy-one years, encompassing seven solar cycles. The sample was divided into four general categories of disease: mental/behavioral illnesses; metabolic diseases; autoimmune diseases; neoplasms. The birth months for those clients born in any given year were arranged in the form of a winter/summer ratio in order to more clearly appreciate the seasonality inherent in each disease category. Solar cycles were separated into chaotic (∼three times as irradiant) or non-chaotic according to the Gutenberg–Richter power law and the uncertainty inherent in predicting solar storms. The results show that radiation peaks in solar cycles and particularly in chaotic solar cycles (CSCs) are associated with a higher incidence of mental disorders, suggesting the sensitivity of ectodermal embryonic tissues to UVR. Autoimmune diseases have intermediate sensitivity, while the neoplasms in the study, primarily of endoderm, appear suppressed by peak UVR intensity. The ratio of the number of clients born in CSC cycles to non-CSC cycles was highest for the more genetic mental diseases, like schizophrenia and bipolar disorder, but as that ratio decreased, the clients with diseases like multiple sclerosis and rheumatoid arthritis showed more environmental features manifested as a greater winter/summer birth month ratio that was significantly different than that of the average client in the whole data set. The paper presents evidence that latitude, e.g., variation in light, is an added stress to the immune system (especially at 53–54°N. latitude) that is involved in nearly all human disease. We hypothesize that introns, the presumptive engenderers of gene control, modulate the effects of UVR, particularly for the neoplasms studied. We conclude that intermittent and largely unpredictable peak solar cycle radiation has been the fundamental engine of evolution, forcing organisms to adapt to mutagenic UVR and producing enough damage to instigate genetic variation. Probably a chance genetic mutation over 80,000 years ago produced a human brain capable of abstract thought and consciousness. The slight genetic instability that favored an adaptable, creative brain also produced other somatic variations that present phenotypically as disease, but largely expressed after natural selection (reproduction) and associated with the inexorable entropy of aging.

Introduction

This paper presents evidence that the ultraviolet radiation (UVR) in 11-year solar cycles influences embryonic tissues through DNA mutation, and predisposes the human organism to various diseases later in life. We show that there is a differential effect of particularly intense cycles that occur more infrequently, cycles that we label chaotic solar cycles (CSCs). Furthermore, we hypothesize that different organ systems have variable sensitivity to sunlight, primarily UVR, because of a differential effect on embryonic tissues, with the pathogenesis most likely related to the immune system and cytokines probably produced by maternal lymphocytes irradiated very early in gestation. In addition, we show that men and women have a different susceptibility to disease and therefore explain why women have greater longevity on average. We discuss the relationship between intensity and variation of sunlight and the seasonal/latitudinal features seen particularly in some autoimmune and neoplastic diseases. We also provide an explanation for the increase in mental illness particularly over the past century, and its relationship to creativity and the process of evolution.

The Sun increases its irradiance every 11 years, actually varying from 8- to 14- years, averaging 11.1 years [1]. Sunpots, the manifestation of magnetic storms on the Sun’s surface, are proxies for radiation intensity, and have been recorded for centuries. During cycle peaks, sunspots increase in number and in size. These peaks are generally predictable using several methodologies, but over a brief period are not predictable with accuracy greater than 72% [2], [3]. Unpredictable irradiance related to chaotic periods in the Sun has been described by physicists [4]. During these particularly intense solar cycles, described in “Methods”, ultraviolet radiation (UVR) may increase up to three-fold in the upper atmosphere, but even the resultant 1–2% increase at ground level is a significant stress to organisms’ DNA-repair mechanisms [5]. UVR is so mutagenic to DNA that the latter is even used as a detector is ultraviolet dosimeters [6]. With so potent a mutagen as UVR in the environment, one would expect that life forms would have to continuously adapt to the intensity and variation of sunlight and that an adaptive response would exist in their genomes. There is evidence based upon millennium-scale sunspot number reconstructions that the Sun has been unusually active since the 1940s, so that adaptative mechanisms would be greatly stressed [7].

The immune system appears to be involved in some way in nearly every disease ranging from somatic to mental disorders. Mental illnesses have been associated with altered T-cell function and an activated innate immune system [8], [9]. Obesity and asthma have recently been associated as well [10], [11]. The medical literature describes many diseases that involve UVR and inflammatory cytokines as mediators [12], [13], [14], [15].

UVR is also found to be immune-suppressive, and hence beneficial, for multiple sclerosis and type 1 diabetes [16]. Therefore, UVR can be harmful or helpful, a true immune modulator, depending upon the disease entity and total exposure.

Over the past several decades the medical literature has been slowly accumulating examples of a predisposition to specific diseases depending upon month of birth (season), time of day (circadian rhythm) and geographic latitude. It was only 22 years ago that Rosenthal first described seasonal affective disorder [17]. There is considerable published literature about season of birth in schizophrenia. Torrey noted that persons afflicted with schizophrenia have 8% excess births in the late winter and early spring [18]. Multiple sclerosis has a greater incidence in higher latitude, especially the United Kingdom and Ireland as well as Canada. Those individuals born in the summer, e.g., conceived in fall and early winter, are epidemiologically more likely to eventually suffer from diabetes, sprue, Crohn’s disease and asthma, while those who are born in the winter, e.g., conceived in late spring and early summer, have a statistical increase in dyslexia, multiple sclerosis, schizophrenia, bipolar disorder, narcolepsy, seizure disorders and autism [19], [20], [21], [22]. One should note that those born in the winter are more likely to have diseases involving tissue derived from embryonic ectoderm destined to become nervous tissue. Those born in the summer appear to suffer more from diseases of embryonic endoderm, destined to become gut, lung and glandular organs. Mesoderm is the anlage of hematopoietic and lymphoid tissues, destined to become the immune system. While the intensity of ultraviolet radiation (UVR) especially in summer months has been long associated with skin cancer, it also appears that variation in UVR and visible light also influences the immune system. For example, research reports indicate that:

• Dermatomyositis is particularly responsive to changing UVR [15].

• Neoplasm may also be sensitive to variable light as related to vitamin D production [23].

• A breast cancer (BC) study revealed that nurses working only in the night shift had 1.5 times more BC than their daytime colleagues, light apparently reducing the incidence of BC [24].

• Chemotherapy is more effective when administered at selected times in the circadian cycles of cell metabolism, suggesting that light modulates the immune system by some mechanism [25].

Different geographic latitudes present different season durations, from no seasons at all at the Equator, e.g., day length is equal to night length, to widely different seasonal light in high latitude where day and night can extend across an entire season. Latitudinal differences in disease incidence have been reported for multiple sclerosis, type-1 diabetes, major depression, rheumatoid arthritis and seasonal affective disorder (SAD). A recent Australian paper presented evidence that these diseases are more common in higher latitude, and rare closer to the Equator [16].

The relatively new technique of photopheresis has shown that UVR modulates the immune system, especially in refractory allograft rejection [26]. In this procedure the patient’s leukocyte-rich plasma is treated with a photosensitizing agent and irradiated with UVR. The re-infused leukocytes result in a dampened response to foreign proteins. Trials have shown that photopheresis is efficacious in Type 1 diabetes and most probably so in graft-versus-host disease [27]. UVR has so profound an effect on the immune system that it must be one of the earliest modulators of one of the most important properties of life, e.g., the differentiation of self from non-self. Furthermore, given the sensitivity of the genome to sunlight, we would expect that varying light conditions would have influenced human evolution.

Marzullo, in a thoroughly researched, compelling monograph, outlined the epidemiologic evidence that birth month had an effect on the hemispheric balance of the brain, e.g., on laterality [28]. This monograph clearly linked cerebral laterality with artistic creativity, a quality more often seen in “right-brain dominant” individuals, who were more often conceived in the high UVR months of May and June. This pattern is also found more often in those with schizophrenia, proposed by Marzullo to be involved with neural tube closure and asymmetry development in the early-fourth week of gestation. Maternal oxidant stress due to exposure to solar radiation was the hypothesized pathogenesis, linked to a photoreceptor and the aldehyde retinal, found in bacteria as well as the human retina, with its chemically-close relative, retinoic acid. The latter compound is responsible for guiding the motility of embryonic cells during the processes of gastrulation and lateralization. Retinoids and carotenoids, which modulate the photonic energy of UVR, and the antioxidant glutathione, underlie an adaptive mechanism that manages potentially damaging UVR. Given these findings, we might expect to find an association between human disease and the intensity and variation of solar radiation.