Disaster trigger: More girls born in Japan after quake skews sex ratio

August 5, 2013 JAPANFewer boys than girls were born in the months after the huge earthquake struck Japan in March 2011. Ralph Catalano of the University of California in Berkeley and colleagues examined hospital records of births in Japan between 2006 and the end of 2011. After the quake, births in areas closest to the epicentre were more likely to be girls, but provinces farther out showed no gender bias. About 2.2 per cent fewer boys were born in the most damaged areas than expected (American Journal of Human Biology, doi.org/nbj). It is not the first time such a skew has been noted: fewer boys were born after the US stock market crash of 2008, for instance. The reason may be evolutionary, says Catalano. Boys are more likely to be premature and suffer problems associated with low birth weight than girls. In times of stress, it may therefore be beneficial for the mother to give birth to a girl. However, it is unclear whether stress causes mothers to miscarry more males or whether fewer males are conceived. Earthquakes provide a natural test for this, Catalano says. If births immediately after show a gender skew, it would suggest that stress is triggering miscarriages. A bias nine months later indicates fewer male conceptions. The team found evidence for both. Several mechanisms may be at work, says Catalano. Fetuses produce a hormone called human chorionic gonadotropin, which camouflages them from the mother’s immune system. Weak male fetuses make less of this hormone, meaning they may be at greater risk of attack. William James of University College London believes the father’s testosterone level plays a role. During periods of high stress, he says, men produce less testosterone, which can reduce the number and quality of the “male” sperm, which carry a Y sex chromosome. –New Scientist
This entry was posted in Civilizations unraveling, Earth Changes, Earth Watch, Earthquake Omens?, High-risk potential hazard zone, Human behavioral change after disaster, Potential Earthchange hotspot, Seismic tremors, Time - Event Acceleration. Bookmark the permalink.

3 Responses to Disaster trigger: More girls born in Japan after quake skews sex ratio

  1. More females are killed in disasters so this may be an attempt to regain balance. Also people are killed in disasters and populations have to be rebuilt. More females will do the job. More males are not likely to make a difference.

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  2. Angelsong says:

    This picture is one I will never forget.. God bless the people of Japan <

    Like

  3. Kajajuk says:

    Perhaps an evolutionary human trait to help rebound from a population decline by favoring more females than males. This is also interesting and indicates that much is still to be learned…

    Like

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