Molecular Genetics

(submitted by LH) In the United States, there is essentially one male for every female. But this series of graphics illustrates that this is not always the case. There are many factors that play into a shift from a bevy of males at birth to a dearth of them at death. Biologically, male humans are more susceptible X-linked diseases than females. Having only a hemizygous state more than doubly increases the likelihood of inheriting a disease allele from a heterozygous mother. There is also the argument that males typically have more dangerous professions and are the major component of combat. Or are simply more likely to endanger themselves.
However, some societies will favour a particular gender over another and will select the sex of their child through IVF. This has led to problems in some countries as the disparity begins to impact the economy and social constructs like marriage.