While astrology is still a load of rubbish, it turns out that your future could actually be written in the stars after all. Well, star.

An intriguing new study conducted in Norway suggests that the sun’s behavior during our year of birth could be influencing several adult life-history traits, including survival, fertility and lifespan. Using a combination of demographic data covering two centuries and solar observations, scientists found that those unlucky enough to be born during periods of high solar activity lived, on average, around five years less than those born in years of solar calm. Furthermore, an angry sun decreased the probability of survival to adulthood, and reduced fertility in women.

Scientists have known for some time that environmental stressors during early development can affect the later survival and reproductive performance of an organism. Exposure to high amounts of UV radiation is one such stressor, the levels of which are known to vary with solar activity. Although scientists aren’t entirely sure how high UV exposure during development causes these detrimental effects, it probably acts through DNA and cellular damage mechanisms.

While the consequences of early UV exposure on the health and reproduction of aquatic animals are well-documented, few studies have looked at humans. To address this gap in our knowledge, scientists from the Norwegian University of Science and Technology examined demographic data from 9,000 individuals born in Norway between 1676 and 1878. The individuals were from two different populations in mid-Norway, which comprised two distinct socioeconomic groups (poor or wealthy). They then compared this information with solar activity data obtained from NOAA.  

Solar activity is measured as the number of dark blemishes, or sunspots, observed on the sun’s surface.  This activity is known to vary in an 11-year cycle, which generally includes eight years of low activity, which is defined as the solar minimum, followed by three years of high activity, or the solar maximum. Solar maxima are marked by more than just an increase in sunspots, however; solar flares and coronal mass ejections also tend to be more commonplace, which are capable of disrupting radio communications and navigational equipment on Earth.

As described in Proceedings of the Royal Society B, they found that, on average, the lifespans of individuals born during a solar maximum period were around five years shorter than those born during a solar minimum. Furthermore, those born during stretches of high solar activity were less likely to survive to adulthood. Additionally, women born during these periods who had lower incomes (and thus probably spent more time outside working) also had lower rates of fertility and reproductive success compared with wealthier women.

You’ve probably already noticed that this study is looking at correlations, and thus cannot prove that solar activity is causing these observed effects. However, the researchers did control for maternal effects, socioeconomic status and ecology, making the results more convincing.

So what could be going on? According to the researchers, high levels of UV radiation could be degrading folate, a type of vitamin B, which is important for the rapid cell proliferation that occurs during pregnancy. Previous work has also found that a shortage of this nutrient before birth is associated with higher rates of disease in adulthood and death.

[Via Proceedings of the Royal Society B, AFP and Live Science]