More difficult for people living in tropical boys

From a biological point of view, said the baby girl's birth is a 50:50 chance. However, according to European media reports, April 1, said a study published in the tropical, temperate and sub-arctic resident ratio of boy or woman there is a clear difference.

 
University of Georgia expert endocrinologists 克里斯滕纳 Guevara CIA collected on 202 countries from 1997 to 2006 the official birth data to study to make such a conclusion. She found that, from a global perspective, the ratio of male and female infants at birth was 51.3% vs 48.7%, slightly more men than women.

 
However, if in accordance with the latitude to differentiate, then the ratio of the various regions have a difference: mothers living closer away from the equator, the more likely to give birth to baby girl, whereas the latitude of residence of mother, the more likely to give birth to baby boy.

 
In the tropics, the baby's birth rate dropped to 51.1%, while areas near the Sahara Desert in Africa, the figure is down 50.8%. Navarre said in an interview: "Obviously the baby was born in the tropics the rate higher. Although all the continents with the Office of tropical countries living habits, social and economic circumstances vary, but overall is a girl more more. "

 
Scientists are not clear reasons for this phenomenon. Navarre suggested that human sperm and eggs may be subject to ambient light and temperature, which might be the reasons for gender differences in birth. Earlier studies have shown that small mammals (including Siberia mice, house mice and voles) shorter in the winter or when the production of sunshine under the larger the ratio of male offspring.
According to reports, the mammalian sex determination in the sperm. Sperm carrying X chromosomes from the embryo and the egg to develop into future baby girl, carrying Y chromosome will develop into the baby, but in theory, with X and Y chromosomes, respectively, the sperm count is the same, thus producing baby boy and baby girl ratio is 50:50. There are data show the baby's birth rate slightly higher than girls, as 106:100. According to scientists, so that the birth sex ratio of men than women died young from the risk of slightly larger.