Solar activity during gestation does not affect human lifespan: evidence from national data

Solar activity at birth predicted infant survival and women's fertility in historical Norway

Ultraviolet radiation (UVR) can suppress essential molecular and cellular mechanisms during early development in living organisms and variations in solar activity during early development may thus influence their health and reproduction. Although the ultimate consequences of UVR on aquatic organisms in early life are well known, similar studies on terrestrial vertebrates, including humans, have remained limited. Using data on temporal variation in sunspot numbers and individual-based demographic data (N = 8662 births) from Norway between 1676 and 1878, while controlling for maternal effects, socioeconomic status, cohort and ecology, we show that solar activity (total solar irradiance) at birth decreased the probability of survival to adulthood for both men and women. On average, the lifespans of individuals born in a solar maximum period were 5.2 years shorter than those born in a solar minimum period. In addition, fertility and lifetime reproductive success (LRS) were reduced among low-status women born in years with high solar activity. The proximate explanation for the relationship between solar activity and infant mortality may be an effect of folate degradation during pregnancy caused by UVR. Our results suggest that solar activity at birth may have consequences for human lifetime performance both within and between generations.

Are stress responses to geomagnetic storms mediated by the cryptochrome compass system?

A controversial body of literature demonstrates associations of geomagnetic storms (GMS) with numerous cardiovascular, psychiatric and behavioural outcomes. Various melatonin hypotheses of GMS have suggested that temporal variation in the geomagnetic field (GMF) may be acting as an additional zeitgeber (a temporal synchronizer) for circadian rhythms, with GMS somehow interfering with the hypothesized system. The cryptochrome genes are known primarily as key components of the circadian pacemaker, ultimately involved in controlling the expression of the hormone melatonin. Cryptochrome is identified as a clear candidate for mediating the effect of GMS on humans, demonstrating the prior existence of several crucial pieces of evidence. A distinct scientific literature demonstrates the widespread use of geomagnetic information for navigation across a range of taxa. One mechanism of magnetoreception is thought to involve a light-dependent retinal molecular system mediated by cryptochrome, acting in a distinct functionality to its established role as a circadian oscillator. There is evidence suggesting that such a magnetosense--or at least the vestiges of it--may exist in humans. This paper argues that cryptochrome is not acting as secondary geomagnetic zeitgeber to influence melatonin synthesis. Instead, it is hypothesized that the cryptochrome compass system is mediating stress responses more broadly across the hypothalamic-pituitary-adrenal (HPA) axis (including alterations to circadian behaviour) in response to changes in the GMF. Two conceptual models are outlined for the existence of such responses--the first as a generalized migrational/dispersal strategy, the second as a stress response to unexpected signals to the magnetosense. It is therefore proposed that GMS lead to disorientation of hormonal systems in animals and humans, thus explaining the effects of GMS on human health and behaviour.

The effect of solar cycles on human lifespan in the 50 United states: variation in light affects the human genome

This paper describes the Sun's effect on the human genome as it relates to lifespan and expands our previous study from the State of Maine to the entire United States and the District of Columbia. In the current study we report that those persons conceived and likely born during the peaks (MAX approximately 3years) of approximately 11-year solar cycles lived an average 1.7years less than those conceived and likely born during non-peaks (MIN approximately 8years). Increased energy at solar MAX, albeit relatively a small 0.1% increase from MIN, apparently modifies the human genome/epigenome and engenders changes that predispose to various diseases, thereby shortening lifespan. It is likely that same energy increases beneficial variety in the genome which may enhance adaptability in a changing environment. This study also reports that living at higher elevations increases exposure to ultraviolet radiation (UVR) and increases the difference between MAX and MIN in the six states at the highest elevations of their population centroids by approximately 13%, further shortening average lifespan about 3 months. How solar energy affects the genome is still not clear. The mechanism could be quantum mechanical (direct effects at a distance) similar to photosynthesis, or mediated by maternal hormones, chemokines or cytokines. The hypothesis is that specific wavelengths of UVR, experienced at critical times in development as at conception or early gestation, and with specific intensity or rate of change, modulates the expression of human diseases. This hypothesis could be readily testable in mice bred to manifest specific diseases.