[El Cid]

History show that a male heavy population is a prelude to war.

Although I don't doubt that this would be the case -- when in history has this ever happened?
It seems like female infanticide, and heavily weighted female abortion, is primarily a disease of this generation.
We're soon going to reap the aftereffects of what has been sown - but I was just wondering if you knew of any historical analogies (or were just making a logical projection).

[Constitutions Grandchild]

Historically, women died in higher numbers from both cultural mores and complications of child birth. Females appear to have had higher birth rates throughout history, but also higher death rates. Males have always had lower birth rates.

When male population is out of balance or when there are prolonged periods of peace, there is less to go around with those cultures in which males are the bread winners, therefore, men start looking over the fence at the grass which appears greener to make ends meet. You will find that societal and perceived lack of resources will fuel war — not just the fact that there are a lot of sex-starved men out there.