In Norway, more sun correlates to reduced inherited fertlity and greater infant mortality

There is a new intriguing paper from The Norwegian University of Science and Technology (NTNU):

G. R. Skjaervo, F. Fossoy, E. Roskaft. Solar activity at birth predicted infant survival and women’s fertility in historical Norway. Proceedings of the Royal Society B: Biological Sciences, 2015; 282 (1801): 20142032 DOI:10.1098/rspb.2014.2032

Researchers studied Norwegian church records of 9,000 people from the period 1750-1900 and looked at life history variables and compared them with environmental factors including solar activity.

NTNU Press Release: Skjærvø and her colleagues found that children born in the years with lots of solar activity had a higher probability of dying compared to children who were born in the years with less solar activity.

On average, the lifespan of children born in years that had a great deal of solar activity was 5.2 years shorter than other children. The largest difference was in the probability of dying during the first two years of life.

Children who were born in years with lots of sunshine and who survived were also more likely to have fewer children, who in turn gave birth to fewer children than others. This finding shows that increased UV radiation during years of high solar activity had an effect across generations.

Skjærvø used information on the number of sunspots as an indication of the amount of UV radiation in a given year. The number of sunspots reaches a maximum every 11 years on average, which results in more UV radiation on Earth during years with high sunspot and solar activity.

UV radiation can have positive effects on human vitamin D levels, but it can also result in a reduction of vitamin B9 (folate). It is known that low folate levels during pregnancy are linked to higher child mortality.

The NTNU study showed that families from the lowest socio-economic groups were most affected by UV radiation. This is probably related to the time period Skjærvø studied, which was a time of clear class distinctions in Norway, especially in rural areas. Women who worked in the fields were more exposed to the sun than other women. In many cases they also had a poorer diet.

If the primary mechanism for such connections is through UV radiation, then it presumably does not have the same impact on those with darker skin. But I suppose that the records from tropical or equatorial regions are not as comprehensive or reliable as old Norwegian church records.

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One Response to “In Norway, more sun correlates to reduced inherited fertlity and greater infant mortality”

  1. Lyla Michaels Says:

    Reblogged this on Conversations I Wish I Had.

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